ISO 3632-2:2010
(Main)Spices — Saffron (Crocus sativus L.) — Part 2: Test methods
Spices — Saffron (Crocus sativus L.) — Part 2: Test methods
ISO 3632-2:2010 specifies test methods for dried saffron obtained from the Crocus sativus L. flower. It is applicable to saffron: a) filaments and cut filaments; b) powder.
Épices — Safran (Crocus sativus L.) — Partie 2: Méthodes d'essai
Začimbe - Žafran (Crocus sativus Linnaeus) - 2. del: Preskusne metode
Ta del ISO 3632 določa preskusno metodo za suh žafran, pridobljen iz rože Crocus sativus L.
Velja za žafranova:
a) vlakna in rezana vlakna;
b) prah.
General Information
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Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 3632-2:2011
01-junij-2011
1DGRPHãþD
SIST ISO 3632-2:1997
=DþLPEHäDIUDQ &URFXVVDWLYXV/LQQDHXV GHO 3UHVNXVQHPHWRGH
Spices -- Saffron (Crocus sativus L.) -- Part 2: Test methods
Épices -- Safran (Crocus sativus L.) -- Partie 2: Méthodes d'essai
Ta slovenski standard je istoveten z: ISO 3632-2:2010
ICS:
67.220.10 =DþLPEH Spices and condiments
SIST ISO 3632-2:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST ISO 3632-2:2011
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SIST ISO 3632-2:2011
INTERNATIONAL ISO
STANDARD 3632-2
First edition
2010-10-01
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
Épices — Safran (Crocus sativus L.) —
Partie 2: Méthodes d'essai
Reference number
ISO 3632-2:2010(E)
©
ISO 2010
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SIST ISO 3632-2:2011
ISO 3632-2:2010(E)
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ii © ISO 2010 – All rights reserved
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SIST ISO 3632-2:2011
ISO 3632-2:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Tests and sample sizes.2
5 Identification test.4
6 Microscopic examination of saffron.5
7 Determination of moisture and volatile matter content.8
8 Determination of floral waste content of saffron in filaments and cut filaments .10
9 Determination of foreign matter content of saffron in filaments and cut filaments.10
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15 and 16 .11
11 Determination of extract soluble in cold water .12
12 Determination of total ash .12
13 Determination of acid-insoluble ash .12
14 Determination of the main characteristics using a UV-vis spectrometric method.12
15 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — Thin-layer chromatography method.14
16 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — High performance liquid chromatography (HPLC) .18
Annex A (informative) Example for the expression of results for a microscopic examination .25
Annex B (informative) Photographic references for microscopic identification.27
Annex C (informative) Example of a UV-vis profile of an aqueous extract of saffron .30
Annex D (informative) Examples of chromatograms .31
Bibliography.36
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SIST ISO 3632-2:2011
ISO 3632-2:2010(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 3632-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 7, Spices,
culinary herbs and condiments.
This second edition of ISO 3632-2 cancels and replaces ISO/TS 3632-2:2003, which has been technically
revised.
ISO 3632 consists of the following parts, under the general title Spices — Saffron (Crocus sativus L.):
⎯ Part 1: Specification
⎯ Part 2: Test methods
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SIST ISO 3632-2:2011
INTERNATIONAL STANDARD ISO 3632-2:2010(E)
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
1 Scope
This part of ISO 3632 specifies test methods for dried saffron obtained from the Crocus sativus L. flower.
It is applicable to saffron:
a) filaments and cut filaments;
b) powder.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 928, Spices and condiments — Determination of total ash
ISO 930, Spices and condiments — Determination of acid-insoluble ash
ISO 941, Spices and condiments — Determination of cold water-soluble extract
ISO 948, Spices and condiments — Sampling
ISO 3632-1, Spices — Saffron (Crocus sativus L.) — Part 1: Specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3632-1 and the following apply.
3.1
moisture and volatile matter content
loss of mass fraction determined under the conditions specified in this part of ISO 3632
NOTE Moisture and volatile matter content is expressed as a percentage mass fraction of the sample.
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3.2
colouring strength
1%
A , 440 nm
1cm
absorbance at the maximum wavelength (about 440 nm) of crocins for a 1 g/100 ml solution of test sample
using a 1 cm quartz cell
NOTE Colouring strength is mainly due to the content of crocins.
3.3
UV-vis profile of saffron extract
spectrum obtained between 200 nm and 700 nm
NOTE An example is given for information in Figure C.1.
3.4
limit of detection
LOD
minimum amount or concentration of the analyte in a test sample which can be detected reliably, but not
necessarily quantified, as demonstrated by a collaborative trial or other appropriate validation
3.5
minimum required performance limit
MRPL
minimum content of an analyte in a sample, which at least has to be detected and confirmed
4 Tests and sample sizes
4.1 Minimum mass of the laboratory sample
Sampling methods for spices and condiments are specified in ISO 948.
Considering the high cost of saffron, the mass of sample received in the laboratories for carrying out the tests
is often limited. The minimum mass of the laboratory sample shall be 23 g (11,5 g × 2) for saffron filaments
and cut filaments and 13,5 g (6,75 g × 2) for saffron powder in order to carry out the standard analyses in
duplicate.
It is recommended that larger quantities of sample be placed at the disposal of the laboratories in case of
dispute.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
4.2 Tests required and test sample sizes
See Table 1 for saffron in filaments, cut filaments and Table 2 for saffron in powder.
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Table 1 — Saffron in filaments and cut filaments forms
Test
Analysis Procedure Corresponding
sample Comments
step (laboratory sample: 11,5 g × 2 = 23 g) clause
g
New test sample
1 Identification test 5 5
Non-destructive test
2 Microscopic examination 0,05 Test sample from step 1 6
Test sample from step 1
3 Determination of floral waste content 3 8
Non-destructive test
Test sample from step 3
4 Determination of foreign matter 3 9
Test sample is reconstituted after
reincorporating floral waste
Determination of extract soluble in
5 2 Test sample from step 4 11
cold water
New test sample
Determination of moisture and
Keep the test sample for
6 2,5 7
volatile matter content
determination of total ash and acid-
insoluble ash
7 Determination of total ash 2 Remains of the test sample from step 6 12
8 Determination of acid-insoluble ash — Test sample produced after step 7 13
New test sample
Carry out the sieving in accordance
with Clause 10 to obtain a powder of
which 95 % mass fraction passes
9 Crushing and sieving 4 10
through a 500 µm sieve.
Reincorporate whatever remains on
the sieve in the receptacle of the
sieve
10 Determination of main characteristics 0,5 Test sample from step 9, after sieving 14
Test sample from step 9, before
sieving
Thin-layer chromatography (TLC):
HPLC (step 12) may alternatively or
11 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 9, before
sieving
High performance liquid
TLC (step 11) may alternatively or
12 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both
methods
NOTE There remain 4,50 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
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SIST ISO 3632-2:2011
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Table 2 — Saffron in powder form
Test
Analysis Procedure Corresponding
sample Comments
step clause
(laboratory sample: 6,75 g × 2 = 13,5 g)
g
New test sample
1 Identification test 0,2 5
Do not continue with the analysis if
the colorimetric analysis is not correct
2 Microscopic examination 0,05 New test sample 6
New test sample
Determination of moisture and volatile
Keep the test sample for
3 2,5 7
matter content
determination of total ash and acid-
insoluble ash
4 Determination of total ash 2 Remains of the test sample from step 3 12
5 Determination of acid-insoluble ash — Remains of the test sample from step 4 13
New test sample
Verify that 95 % mass fraction of the
powder passes through a 500 µm
6 Crushing and sieving 4 10
sieve. Reincorporate whatever
remains on the sieve in the receptacle
of the sieve
Determination of extract soluble in cold
7 2 Test sample from step 6 11
water
8 Determination of main characteristics 0,5 Test sample from step 6, after sieving 14
Test sample from step 6, before
sieving
Thin-layer chromatography (TLC):
HPLC (10) may alternatively or
9 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 6, before sieving
High performance liquid
TLC (9) may alternatively or
10 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both methods
NOTE There remain 1 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
5 Identification test
5.1 General
This preliminary test may make the subsequent analyses unnecessary if it shows that the saffron is not pure.
5.2 Saffron in filaments and cut filaments
5.2.1 Principle
The saffron is examined visually with a magnifying glass.
5.2.2 Apparatus
5.2.2.1 Magnifying glass, with a magnification of 10 times max.
5.2.2.2 Watch glass, of suitable size.
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5.2.3 Procedure
Spread out the test sample of saffron in filaments and cut filaments (Table 1) on the watch glass (5.2.2.2) and
examine it with the magnifying glass (5.2.2.1).
5.2.4 Interpretation of results
All the filaments shall belong to the plant Crocus sativus L.
Reject the sample if vegetable matter other than that belonging to Crocus sativus L. is found.
5.3 Saffron in powder form
5.3.1 Principle
A colorimetric reaction is used.
5.3.2 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent quality.
5.3.2.1 Sulfuric acid, mass concentration 1,19 g/l.
5.3.2.2 Diphenylamine solution. Add 0,1 g diphenylamine to 20 ml sulfuric acid (5.3.2.1) and 4 ml water.
The diphenylamine shall not produce any coloured reaction with the sulfuric acid.
5.3.3 Porcelain dish, with flat bottom.
5.3.4 Procedure
Use the 0,2 g test sample of saffron (see Table 2) as test portion.
Gradually add the test portion to the porcelain dish (5.3.3) containing the diphenylamine solution (5.3.2.2).
5.3.5 Interpretation of results
Pure saffron immediately produces a blue colour, which rapidly turns reddish brown.
In the presence of nitrates, the blue colour persists.
6 Microscopic examination of saffron
6.1 General
The method is applicable to the examination of saffron in powder, filaments, and cut filament forms in order to
determine whether the sample consists exclusively of stigmas belonging to Crocus sativus L. and to highlight
any floral waste and foreign matter.
6.2 Principle
The identity of saffron in powder and crushed filament form is verified. Foreign matter and floral waste, if any,
are identified by the observation of anatomical elements by using microscopy under the conditions described in
6.5. The percentages relating to the observed elements may be determined if required (see Annexes A and B).
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SIST ISO 3632-2:2011
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6.3 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent purity.
6.3.1 Iodine in iodide solution, aqueous solution of iodine in potassium iodide.
In a 100 ml one-mark volumetric flask (6.4.5), equipped with a glass stopper, add 2 g iodine, 4 g potassium
iodide, and about 10 ml water. Leave until completely dissolved, then make up to the mark with water. Stopper
the flask.
6.3.2 Illuminating solution, either sodium hydroxide or potassium hydroxide at a mass concentration of
5 g/100 ml water or chloral hydrate with 80 g/100 ml water; dissolve when hot.
6.4 Apparatus
Usual laboratory equipment and in particular the following.
6.4.1 Slides.
6.4.2 Cover-glasses.
6.4.3 Scalpel.
6.4.4 Lancet needles.
[4]
6.4.5 One-mark volumetric flask, capacity 100 ml, ISO 1042 class A.
6.4.6 Syringe, graduated in microlitres, capable of delivering volumes of 50 µl.
6.4.7 Microscope, permitting observation with a magnification of 100 times and 400 times, optionally
equipped with a device permitting observation in polarized light.
6.5 Procedure
6.5.1 Test portion
For each slide (6.5.2 to 6.5.4), take a test portion of the order of 0,001 g to 0,002 g saffron in powder
(see 10.3) or crushed filament (see 10.2) form.
6.5.2 Preparation for observation in water
Prepare two slides as follows.
Deposit 50 µl of water on a slide. Using the tip of a scalpel or lancet needle, take the test portion (6.5.1), mix it
with the water and wait for at least 5 min to ensure that the powder is adequately wet before covering with a
cover slide.
6.5.3 Preparation for observation in an aqueous solution of sodium hydroxide, potassium hydroxide
or chloral hydrate
Prepare two slides as indicated in 6.5.2, but replace water with the sodium hydroxide, potassium hydroxide or
chloral hydrate aqueous solutions (6.3.2).
Wait for a few minutes for the medium to illuminate and observe for 10 min after adding the illuminating
solution in order to avoid altering the cellular elements and ensuring they can be identified.
NOTE This observation enables illumination of the preparations by destroying totally or partially the major part of the
cellular contents. The cellular elements are also made clearer and easier to observe, particularly the sclerous elements,
vessels, fibres and epidermis.
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6.5.4 Preparation for observation in aqueous iodine in iodide solution
Prepare a slide as indicated in 6.5.2, but replace the water with iodine in iodide solution (6.3.1).
NOTE This observation makes visible the starch grains which are stained blackish blue or blackish violet.
6.5.5 Observation, identification, and counting
Place each slide, prepared according to 6.5.2 to 6.5.4, under the microscope (6.4.7). Set the magnification at
100 times. Identify and count the elements observed with a magnification of 400 times (see 6.7).
NOTE The anatomical structures and exogenous elements are identified and counted for each slide on an
observation of 10 fields.
If the microscope used (6.4.7) is equipped with a device permitting observation in polarized light, one of the
two slides prepared in 6.5.2 should be so observed.
Figure 1 shows an example which summarizes all operations permitting counting.
Key
A field
B slide
Figure 1 — Example of counting procedure
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SIST ISO 3632-2:2011
ISO 3632-2:2010(E)
6.6 Expression of results
An example is given for information in Annex A.
6.7 Microscopic examination
See reference photographs given for information in Annex B.
During the examination, the following elements can be observed:
a) fragments of the top extremity of the stigmas with large hair-like elongated papillae, after crushing the
isolated papillae (Figure B.1);
b) epidermic debris of the stigmas which are characterized by small intussusceptions of the membrane
(Figure B.2);
c) debris of the epidermis of the style, characterized by a sinuous wall (Figure B.3);
d) round pollen grains with a diameter of between 80 µm and 100 µm, with a smooth cell wall and finely
granular exine (Figure B.4);
e) fragments of conductor elements made up of spiralled vessels (Figure B.5);
f) fragments of stamens (Figure B.6);
g) grains of starch (Figure B.7);
h) inorganic matter (Figure B.8);
i) fragments of straw (Figure B.9);
j) cells the content of which remain coloured despite the illuminating solution (Figure B.10).
6.8 Interpretation of microscopic observations
Evaluation of the relative percentage of each structure evaluated from the count table permits a check that the
crushed saffron is mainly made up of fragments of stigmas to which fragments of styles and grains of pollen
can be associated.
The observation should be reported in accordance with Tables A.1 and A.2.
NOTE The crushed saffron does not have sclerous cells, fibres, covert hair or starch grains. The contents of the cells
dissolve in water to give an orange-yellow colour.
7 Determination of moisture and volatile matter content
7.1 General
This method is applicable to saffron in filaments, cut filaments and in powder forms.
[3]
NOTE The method of determination of the moisture content of spices and condiments described in ISO 939 is not
applicable in the case of saffron because it requires the use of too large a test portion.
7.2 Principle
The sample is oven dried at 103 °C ± 2 °C for 16 h.
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7.3 Apparatus
Usual laboratory apparatus and in particular the following.
7.3.1 Weighing dish or evaporating dish, provided with a lid or shoe glass.
7.3.2 Oven, capable of being maintained at 103 °C ± 2 °C.
7.3.3 Desiccator, containing an effective desiccant.
7.3.4 Analytical balance, capable of being read to the nearest 0,001 g.
7.4 Procedure
7.4.1 Test portion
7.4.1.1 Saffron in filaments and cut filaments
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 1) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.1.2 Saffron in powder form
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 2) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.2 Determination
Place the weighing dish or evaporating dish containing the test portion (7.4.1.1 or 7.4.1.2) uncovered in the
oven (7.3.2) maintained at 103 °C and leave for 16 h. Cover with the lid or shoe glass, and allow it to cool in
the desiccator (7.3.3). After cooling, weigh to the nearest 0,001 g.
Conserve the product for the later determination of total ashes (see Clause 12) and acid-insoluble ash (see
Clause 13).
Carry out two determinations on the same laboratory sample.
7.5 Expression of results
The moisture and volatile matter content, w , expressed as a percentage of the initial sample is equal to:
MV
100
wm=−m× %
()
MV 0 4
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the dry residue.
4
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
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8 Determination of floral waste content of saffron in filaments and cut filaments
8.1 Principle
The floral waste present in a test portion is physically separated then weighed.
8.2 Apparatus
8.2.1 Watch glass.
8.2.2 Small laboratory tongs.
8.2.3 Analytical balance, capable of weighing to the nearest 0,01 g.
8.3 Procedure
8.3.1 Test portion
Weigh, to the nearest 0,01 g approximately 3 g of the test sample.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
8.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs (8.2.2), separate the
different components of floral waste. Weigh on the analytical balance (8.2.3) to the nearest 0,01 g the
previously dried watch glass (8.2.1).
Transfer the separated floral wastes to the shoe glass and weigh the whole to the nearest 0,01 g.
8.4 Expression of results
The floral waste content of the sample, w , expressed as a percentage by mass, is equal to:
F
100
wm=−m× %
()
F2 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the shoe glass containing the floral waste.
2
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
9 Determination of foreign matter content of saffron in filaments and cut filaments
9.1 Principle
The foreign matter present in a test portion is separated physically then weighed.
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9.2 Apparatus
Use the same apparatus as specified in Clause 8.
9.3 Procedure
9.3.1 Test portion
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
Reconstitute the test sample (approx. 3 g) by reincorporating the floral wastes previously separated and
determined as in Clause 8, for saffron filaments and cut filaments. Homogenize well and then weigh the
sample to the nearest 0,01 g.
9.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs, or with other
appropriate means, separate the foreign matter from the test portion.
Weigh, to the nearest 0,01 g, the previously dried shoe glass.
Transfer the separated foreign matter to the shoe glass and weigh the whole to the nearest 0,01 g.
9.4 Expression of results
The foreign matter content of the sample, w , expressed as a percentage by mass, is equal to:
FM
100
wm=−m× %
()
FM 3 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the watch glass containing the foreign matter.
3
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15
and 16
10.1 Apparatus
10.1.1 Crusher, which shall:
a) be easy to dismantle and to clean, and have a minimum dead space;
b) permit a quick and uniform crushing without causing heat or loss of moisture;
c) avoid contact with the ambient air as much as possible;
d) permit a total recovery of all fragments of the sample;
e) not introduce any foreign substance into the sample.
[1]
10.1.2 Sieve, of 500 µm mesh, ISO 565 .
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10.2 Saffron in filaments and cut filaments
Crush the test sample (see Table 1) using the crusher (10.1.1) until 95 % mass fraction of the powder passes
through the sieve (10.1.2).
Then, reincorporate the material remaining on the sieve and homogenize the whole.
10.3 Saffron in powder form
Sieve the test sample (see Table 2) using the sieve (10.1.2) in order to verify that 95 % mass fraction of the
powder passes through it.
If this is not the case, crush the powder in the crusher (10.1.1) to obtain the required particle size.
Then, reincorporate the material remaining on the sieve and homogenize the whole.
11 Determination of extract soluble in cold water
Proceed in accordance with the method given in ISO 941.
For saffron in filaments, cut filaments and in powder forms, take a test portion of 2,00 g ± 0,01 g.
12 Determination of total ash
Proceed in accordance with the method given in ISO 928.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the moisture content (7.4.2).
13 Determination of acid-insoluble ash
Proceed in accordance with the method given in ISO 930.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the total ash (Clause 12).
14 Determination of the main characteristics using a UV-vis spectrometric method
14.1 General
This method enables the determination of the main characteristics of saffron connected with picrocrocin,
safranal and crocin content. It is directly applicable to saffron in powder form provided that the powder
conforms to the requirements of 10.3 and to saffron filaments and cut filaments after crushing and sieving in
accordance with 10.2.
14.2 Principle
Measurement of the variation in optical density between 200 nm and 7
...
INTERNATIONAL ISO
STANDARD 3632-2
First edition
2010-10-01
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
Épices — Safran (Crocus sativus L.) —
Partie 2: Méthodes d'essai
Reference number
ISO 3632-2:2010(E)
©
ISO 2010
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ISO 3632-2:2010(E)
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
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Published in Switzerland
ii © ISO 2010 – All rights reserved
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ISO 3632-2:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Tests and sample sizes.2
5 Identification test.4
6 Microscopic examination of saffron.5
7 Determination of moisture and volatile matter content.8
8 Determination of floral waste content of saffron in filaments and cut filaments .10
9 Determination of foreign matter content of saffron in filaments and cut filaments.10
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15 and 16 .11
11 Determination of extract soluble in cold water .12
12 Determination of total ash .12
13 Determination of acid-insoluble ash .12
14 Determination of the main characteristics using a UV-vis spectrometric method.12
15 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — Thin-layer chromatography method.14
16 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — High performance liquid chromatography (HPLC) .18
Annex A (informative) Example for the expression of results for a microscopic examination .25
Annex B (informative) Photographic references for microscopic identification.27
Annex C (informative) Example of a UV-vis profile of an aqueous extract of saffron .30
Annex D (informative) Examples of chromatograms .31
Bibliography.36
© ISO 2010 – All rights reserved iii
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ISO 3632-2:2010(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 3632-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 7, Spices,
culinary herbs and condiments.
This second edition of ISO 3632-2 cancels and replaces ISO/TS 3632-2:2003, which has been technically
revised.
ISO 3632 consists of the following parts, under the general title Spices — Saffron (Crocus sativus L.):
⎯ Part 1: Specification
⎯ Part 2: Test methods
iv © ISO 2010 – All rights reserved
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INTERNATIONAL STANDARD ISO 3632-2:2010(E)
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
1 Scope
This part of ISO 3632 specifies test methods for dried saffron obtained from the Crocus sativus L. flower.
It is applicable to saffron:
a) filaments and cut filaments;
b) powder.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 928, Spices and condiments — Determination of total ash
ISO 930, Spices and condiments — Determination of acid-insoluble ash
ISO 941, Spices and condiments — Determination of cold water-soluble extract
ISO 948, Spices and condiments — Sampling
ISO 3632-1, Spices — Saffron (Crocus sativus L.) — Part 1: Specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3632-1 and the following apply.
3.1
moisture and volatile matter content
loss of mass fraction determined under the conditions specified in this part of ISO 3632
NOTE Moisture and volatile matter content is expressed as a percentage mass fraction of the sample.
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ISO 3632-2:2010(E)
3.2
colouring strength
1%
A , 440 nm
1cm
absorbance at the maximum wavelength (about 440 nm) of crocins for a 1 g/100 ml solution of test sample
using a 1 cm quartz cell
NOTE Colouring strength is mainly due to the content of crocins.
3.3
UV-vis profile of saffron extract
spectrum obtained between 200 nm and 700 nm
NOTE An example is given for information in Figure C.1.
3.4
limit of detection
LOD
minimum amount or concentration of the analyte in a test sample which can be detected reliably, but not
necessarily quantified, as demonstrated by a collaborative trial or other appropriate validation
3.5
minimum required performance limit
MRPL
minimum content of an analyte in a sample, which at least has to be detected and confirmed
4 Tests and sample sizes
4.1 Minimum mass of the laboratory sample
Sampling methods for spices and condiments are specified in ISO 948.
Considering the high cost of saffron, the mass of sample received in the laboratories for carrying out the tests
is often limited. The minimum mass of the laboratory sample shall be 23 g (11,5 g × 2) for saffron filaments
and cut filaments and 13,5 g (6,75 g × 2) for saffron powder in order to carry out the standard analyses in
duplicate.
It is recommended that larger quantities of sample be placed at the disposal of the laboratories in case of
dispute.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
4.2 Tests required and test sample sizes
See Table 1 for saffron in filaments, cut filaments and Table 2 for saffron in powder.
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ISO 3632-2:2010(E)
Table 1 — Saffron in filaments and cut filaments forms
Test
Analysis Procedure Corresponding
sample Comments
step (laboratory sample: 11,5 g × 2 = 23 g) clause
g
New test sample
1 Identification test 5 5
Non-destructive test
2 Microscopic examination 0,05 Test sample from step 1 6
Test sample from step 1
3 Determination of floral waste content 3 8
Non-destructive test
Test sample from step 3
4 Determination of foreign matter 3 9
Test sample is reconstituted after
reincorporating floral waste
Determination of extract soluble in
5 2 Test sample from step 4 11
cold water
New test sample
Determination of moisture and
Keep the test sample for
6 2,5 7
volatile matter content
determination of total ash and acid-
insoluble ash
7 Determination of total ash 2 Remains of the test sample from step 6 12
8 Determination of acid-insoluble ash — Test sample produced after step 7 13
New test sample
Carry out the sieving in accordance
with Clause 10 to obtain a powder of
which 95 % mass fraction passes
9 Crushing and sieving 4 10
through a 500 µm sieve.
Reincorporate whatever remains on
the sieve in the receptacle of the
sieve
10 Determination of main characteristics 0,5 Test sample from step 9, after sieving 14
Test sample from step 9, before
sieving
Thin-layer chromatography (TLC):
HPLC (step 12) may alternatively or
11 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 9, before
sieving
High performance liquid
TLC (step 11) may alternatively or
12 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both
methods
NOTE There remain 4,50 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
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ISO 3632-2:2010(E)
Table 2 — Saffron in powder form
Test
Analysis Procedure Corresponding
sample Comments
step clause
(laboratory sample: 6,75 g × 2 = 13,5 g)
g
New test sample
1 Identification test 0,2 5
Do not continue with the analysis if
the colorimetric analysis is not correct
2 Microscopic examination 0,05 New test sample 6
New test sample
Determination of moisture and volatile
Keep the test sample for
3 2,5 7
matter content
determination of total ash and acid-
insoluble ash
4 Determination of total ash 2 Remains of the test sample from step 3 12
5 Determination of acid-insoluble ash — Remains of the test sample from step 4 13
New test sample
Verify that 95 % mass fraction of the
powder passes through a 500 µm
6 Crushing and sieving 4 10
sieve. Reincorporate whatever
remains on the sieve in the receptacle
of the sieve
Determination of extract soluble in cold
7 2 Test sample from step 6 11
water
8 Determination of main characteristics 0,5 Test sample from step 6, after sieving 14
Test sample from step 6, before
sieving
Thin-layer chromatography (TLC):
HPLC (10) may alternatively or
9 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 6, before sieving
High performance liquid
TLC (9) may alternatively or
10 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both methods
NOTE There remain 1 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
5 Identification test
5.1 General
This preliminary test may make the subsequent analyses unnecessary if it shows that the saffron is not pure.
5.2 Saffron in filaments and cut filaments
5.2.1 Principle
The saffron is examined visually with a magnifying glass.
5.2.2 Apparatus
5.2.2.1 Magnifying glass, with a magnification of 10 times max.
5.2.2.2 Watch glass, of suitable size.
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ISO 3632-2:2010(E)
5.2.3 Procedure
Spread out the test sample of saffron in filaments and cut filaments (Table 1) on the watch glass (5.2.2.2) and
examine it with the magnifying glass (5.2.2.1).
5.2.4 Interpretation of results
All the filaments shall belong to the plant Crocus sativus L.
Reject the sample if vegetable matter other than that belonging to Crocus sativus L. is found.
5.3 Saffron in powder form
5.3.1 Principle
A colorimetric reaction is used.
5.3.2 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent quality.
5.3.2.1 Sulfuric acid, mass concentration 1,19 g/l.
5.3.2.2 Diphenylamine solution. Add 0,1 g diphenylamine to 20 ml sulfuric acid (5.3.2.1) and 4 ml water.
The diphenylamine shall not produce any coloured reaction with the sulfuric acid.
5.3.3 Porcelain dish, with flat bottom.
5.3.4 Procedure
Use the 0,2 g test sample of saffron (see Table 2) as test portion.
Gradually add the test portion to the porcelain dish (5.3.3) containing the diphenylamine solution (5.3.2.2).
5.3.5 Interpretation of results
Pure saffron immediately produces a blue colour, which rapidly turns reddish brown.
In the presence of nitrates, the blue colour persists.
6 Microscopic examination of saffron
6.1 General
The method is applicable to the examination of saffron in powder, filaments, and cut filament forms in order to
determine whether the sample consists exclusively of stigmas belonging to Crocus sativus L. and to highlight
any floral waste and foreign matter.
6.2 Principle
The identity of saffron in powder and crushed filament form is verified. Foreign matter and floral waste, if any,
are identified by the observation of anatomical elements by using microscopy under the conditions described in
6.5. The percentages relating to the observed elements may be determined if required (see Annexes A and B).
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ISO 3632-2:2010(E)
6.3 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent purity.
6.3.1 Iodine in iodide solution, aqueous solution of iodine in potassium iodide.
In a 100 ml one-mark volumetric flask (6.4.5), equipped with a glass stopper, add 2 g iodine, 4 g potassium
iodide, and about 10 ml water. Leave until completely dissolved, then make up to the mark with water. Stopper
the flask.
6.3.2 Illuminating solution, either sodium hydroxide or potassium hydroxide at a mass concentration of
5 g/100 ml water or chloral hydrate with 80 g/100 ml water; dissolve when hot.
6.4 Apparatus
Usual laboratory equipment and in particular the following.
6.4.1 Slides.
6.4.2 Cover-glasses.
6.4.3 Scalpel.
6.4.4 Lancet needles.
[4]
6.4.5 One-mark volumetric flask, capacity 100 ml, ISO 1042 class A.
6.4.6 Syringe, graduated in microlitres, capable of delivering volumes of 50 µl.
6.4.7 Microscope, permitting observation with a magnification of 100 times and 400 times, optionally
equipped with a device permitting observation in polarized light.
6.5 Procedure
6.5.1 Test portion
For each slide (6.5.2 to 6.5.4), take a test portion of the order of 0,001 g to 0,002 g saffron in powder
(see 10.3) or crushed filament (see 10.2) form.
6.5.2 Preparation for observation in water
Prepare two slides as follows.
Deposit 50 µl of water on a slide. Using the tip of a scalpel or lancet needle, take the test portion (6.5.1), mix it
with the water and wait for at least 5 min to ensure that the powder is adequately wet before covering with a
cover slide.
6.5.3 Preparation for observation in an aqueous solution of sodium hydroxide, potassium hydroxide
or chloral hydrate
Prepare two slides as indicated in 6.5.2, but replace water with the sodium hydroxide, potassium hydroxide or
chloral hydrate aqueous solutions (6.3.2).
Wait for a few minutes for the medium to illuminate and observe for 10 min after adding the illuminating
solution in order to avoid altering the cellular elements and ensuring they can be identified.
NOTE This observation enables illumination of the preparations by destroying totally or partially the major part of the
cellular contents. The cellular elements are also made clearer and easier to observe, particularly the sclerous elements,
vessels, fibres and epidermis.
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ISO 3632-2:2010(E)
6.5.4 Preparation for observation in aqueous iodine in iodide solution
Prepare a slide as indicated in 6.5.2, but replace the water with iodine in iodide solution (6.3.1).
NOTE This observation makes visible the starch grains which are stained blackish blue or blackish violet.
6.5.5 Observation, identification, and counting
Place each slide, prepared according to 6.5.2 to 6.5.4, under the microscope (6.4.7). Set the magnification at
100 times. Identify and count the elements observed with a magnification of 400 times (see 6.7).
NOTE The anatomical structures and exogenous elements are identified and counted for each slide on an
observation of 10 fields.
If the microscope used (6.4.7) is equipped with a device permitting observation in polarized light, one of the
two slides prepared in 6.5.2 should be so observed.
Figure 1 shows an example which summarizes all operations permitting counting.
Key
A field
B slide
Figure 1 — Example of counting procedure
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ISO 3632-2:2010(E)
6.6 Expression of results
An example is given for information in Annex A.
6.7 Microscopic examination
See reference photographs given for information in Annex B.
During the examination, the following elements can be observed:
a) fragments of the top extremity of the stigmas with large hair-like elongated papillae, after crushing the
isolated papillae (Figure B.1);
b) epidermic debris of the stigmas which are characterized by small intussusceptions of the membrane
(Figure B.2);
c) debris of the epidermis of the style, characterized by a sinuous wall (Figure B.3);
d) round pollen grains with a diameter of between 80 µm and 100 µm, with a smooth cell wall and finely
granular exine (Figure B.4);
e) fragments of conductor elements made up of spiralled vessels (Figure B.5);
f) fragments of stamens (Figure B.6);
g) grains of starch (Figure B.7);
h) inorganic matter (Figure B.8);
i) fragments of straw (Figure B.9);
j) cells the content of which remain coloured despite the illuminating solution (Figure B.10).
6.8 Interpretation of microscopic observations
Evaluation of the relative percentage of each structure evaluated from the count table permits a check that the
crushed saffron is mainly made up of fragments of stigmas to which fragments of styles and grains of pollen
can be associated.
The observation should be reported in accordance with Tables A.1 and A.2.
NOTE The crushed saffron does not have sclerous cells, fibres, covert hair or starch grains. The contents of the cells
dissolve in water to give an orange-yellow colour.
7 Determination of moisture and volatile matter content
7.1 General
This method is applicable to saffron in filaments, cut filaments and in powder forms.
[3]
NOTE The method of determination of the moisture content of spices and condiments described in ISO 939 is not
applicable in the case of saffron because it requires the use of too large a test portion.
7.2 Principle
The sample is oven dried at 103 °C ± 2 °C for 16 h.
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ISO 3632-2:2010(E)
7.3 Apparatus
Usual laboratory apparatus and in particular the following.
7.3.1 Weighing dish or evaporating dish, provided with a lid or shoe glass.
7.3.2 Oven, capable of being maintained at 103 °C ± 2 °C.
7.3.3 Desiccator, containing an effective desiccant.
7.3.4 Analytical balance, capable of being read to the nearest 0,001 g.
7.4 Procedure
7.4.1 Test portion
7.4.1.1 Saffron in filaments and cut filaments
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 1) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.1.2 Saffron in powder form
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 2) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.2 Determination
Place the weighing dish or evaporating dish containing the test portion (7.4.1.1 or 7.4.1.2) uncovered in the
oven (7.3.2) maintained at 103 °C and leave for 16 h. Cover with the lid or shoe glass, and allow it to cool in
the desiccator (7.3.3). After cooling, weigh to the nearest 0,001 g.
Conserve the product for the later determination of total ashes (see Clause 12) and acid-insoluble ash (see
Clause 13).
Carry out two determinations on the same laboratory sample.
7.5 Expression of results
The moisture and volatile matter content, w , expressed as a percentage of the initial sample is equal to:
MV
100
wm=−m× %
()
MV 0 4
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the dry residue.
4
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
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ISO 3632-2:2010(E)
8 Determination of floral waste content of saffron in filaments and cut filaments
8.1 Principle
The floral waste present in a test portion is physically separated then weighed.
8.2 Apparatus
8.2.1 Watch glass.
8.2.2 Small laboratory tongs.
8.2.3 Analytical balance, capable of weighing to the nearest 0,01 g.
8.3 Procedure
8.3.1 Test portion
Weigh, to the nearest 0,01 g approximately 3 g of the test sample.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
8.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs (8.2.2), separate the
different components of floral waste. Weigh on the analytical balance (8.2.3) to the nearest 0,01 g the
previously dried watch glass (8.2.1).
Transfer the separated floral wastes to the shoe glass and weigh the whole to the nearest 0,01 g.
8.4 Expression of results
The floral waste content of the sample, w , expressed as a percentage by mass, is equal to:
F
100
wm=−m× %
()
F2 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the shoe glass containing the floral waste.
2
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
9 Determination of foreign matter content of saffron in filaments and cut filaments
9.1 Principle
The foreign matter present in a test portion is separated physically then weighed.
10 © ISO 2010 – All rights reserved
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ISO 3632-2:2010(E)
9.2 Apparatus
Use the same apparatus as specified in Clause 8.
9.3 Procedure
9.3.1 Test portion
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
Reconstitute the test sample (approx. 3 g) by reincorporating the floral wastes previously separated and
determined as in Clause 8, for saffron filaments and cut filaments. Homogenize well and then weigh the
sample to the nearest 0,01 g.
9.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs, or with other
appropriate means, separate the foreign matter from the test portion.
Weigh, to the nearest 0,01 g, the previously dried shoe glass.
Transfer the separated foreign matter to the shoe glass and weigh the whole to the nearest 0,01 g.
9.4 Expression of results
The foreign matter content of the sample, w , expressed as a percentage by mass, is equal to:
FM
100
wm=−m× %
()
FM 3 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the watch glass containing the foreign matter.
3
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15
and 16
10.1 Apparatus
10.1.1 Crusher, which shall:
a) be easy to dismantle and to clean, and have a minimum dead space;
b) permit a quick and uniform crushing without causing heat or loss of moisture;
c) avoid contact with the ambient air as much as possible;
d) permit a total recovery of all fragments of the sample;
e) not introduce any foreign substance into the sample.
[1]
10.1.2 Sieve, of 500 µm mesh, ISO 565 .
© ISO 2010 – All rights reserved 11
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ISO 3632-2:2010(E)
10.2 Saffron in filaments and cut filaments
Crush the test sample (see Table 1) using the crusher (10.1.1) until 95 % mass fraction of the powder passes
through the sieve (10.1.2).
Then, reincorporate the material remaining on the sieve and homogenize the whole.
10.3 Saffron in powder form
Sieve the test sample (see Table 2) using the sieve (10.1.2) in order to verify that 95 % mass fraction of the
powder passes through it.
If this is not the case, crush the powder in the crusher (10.1.1) to obtain the required particle size.
Then, reincorporate the material remaining on the sieve and homogenize the whole.
11 Determination of extract soluble in cold water
Proceed in accordance with the method given in ISO 941.
For saffron in filaments, cut filaments and in powder forms, take a test portion of 2,00 g ± 0,01 g.
12 Determination of total ash
Proceed in accordance with the method given in ISO 928.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the moisture content (7.4.2).
13 Determination of acid-insoluble ash
Proceed in accordance with the method given in ISO 930.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the total ash (Clause 12).
14 Determination of the main characteristics using a UV-vis spectrometric method
14.1 General
This method enables the determination of the main characteristics of saffron connected with picrocrocin,
safranal and crocin content. It is directly applicable to saffron in powder form provided that the powder
conforms to the requirements of 10.3 and to saffron filaments and cut filaments after crushing and sieving in
accordance with 10.2.
14.2 Principle
Measurement of the variation in optical density between 200 nm and 700 nm of an aqueous extract of saffron
at ambient temperature.
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ISO 3632-2:2010(E)
14.3 Apparatus
Usual laboratory equipment and in particular the following.
14.3.1 Spectrometer, suitable for recording optical density in the ultraviolet-visible (UV-vis) band between
200 nm and 700 nm.
14.3.2 Quartz cell, with an optical pathlength of 1 cm.
[4]
14.3.3 One-mark volumetric flasks, capacity 200 ml and 1 000 ml, ISO 1042 class A, in anti-actinic glass.
[2]
14.3.4 One-mark pipette, capacity 20 ml, ISO 648 class A.
14.3.5 Filtration membrane, made of cellulose acetate or made of hydrophilic polytetrafluoroethylene
1)
(PTFE) [Millex-LCR ] of porosity 0,45 µm.
14.4 Procedure
14.4.1 Test portion
Weigh, to the nearest milligram, 500 mg of the sample (see Table 1 or Table 2) in a shoe glass.
14.4.2 Determination
Transfer quantitatively the test portion into a 1 000 ml one-mark volumetric flask (14.3.3). Add about 90
...
SLOVENSKI STANDARD
oSIST ISO 3632-2:2011
01-april-2011
=DþLPEHäDIUDQ &URFXVVDWLYXV/LQQDHXV GHO 3UHVNXVQHPHWRGH
Spices -- Saffron (Crocus sativus L.) -- Part 2: Test methods
Épices -- Safran (Crocus sativus L.) -- Partie 2: Méthodes d'essai
Ta slovenski standard je istoveten z: ISO 3632-2:2010
ICS:
67.220.10 =DþLPEH Spices and condiments
oSIST ISO 3632-2:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST ISO 3632-2:2011
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oSIST ISO 3632-2:2011
INTERNATIONAL ISO
STANDARD 3632-2
First edition
2010-10-01
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
Épices — Safran (Crocus sativus L.) —
Partie 2: Méthodes d'essai
Reference number
ISO 3632-2:2010(E)
©
ISO 2010
---------------------- Page: 3 ----------------------
oSIST ISO 3632-2:2011
ISO 3632-2:2010(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO 2010
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
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oSIST ISO 3632-2:2011
ISO 3632-2:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Tests and sample sizes.2
5 Identification test.4
6 Microscopic examination of saffron.5
7 Determination of moisture and volatile matter content.8
8 Determination of floral waste content of saffron in filaments and cut filaments .10
9 Determination of foreign matter content of saffron in filaments and cut filaments.10
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15 and 16 .11
11 Determination of extract soluble in cold water .12
12 Determination of total ash .12
13 Determination of acid-insoluble ash .12
14 Determination of the main characteristics using a UV-vis spectrometric method.12
15 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — Thin-layer chromatography method.14
16 Detection of artificial coloring: identification of synthetic water-soluble acidic
colorants — High performance liquid chromatography (HPLC) .18
Annex A (informative) Example for the expression of results for a microscopic examination .25
Annex B (informative) Photographic references for microscopic identification.27
Annex C (informative) Example of a UV-vis profile of an aqueous extract of saffron .30
Annex D (informative) Examples of chromatograms .31
Bibliography.36
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oSIST ISO 3632-2:2011
ISO 3632-2:2010(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 3632-2 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 7, Spices,
culinary herbs and condiments.
This second edition of ISO 3632-2 cancels and replaces ISO/TS 3632-2:2003, which has been technically
revised.
ISO 3632 consists of the following parts, under the general title Spices — Saffron (Crocus sativus L.):
⎯ Part 1: Specification
⎯ Part 2: Test methods
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oSIST ISO 3632-2:2011
INTERNATIONAL STANDARD ISO 3632-2:2010(E)
Spices — Saffron (Crocus sativus L.) —
Part 2:
Test methods
1 Scope
This part of ISO 3632 specifies test methods for dried saffron obtained from the Crocus sativus L. flower.
It is applicable to saffron:
a) filaments and cut filaments;
b) powder.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 928, Spices and condiments — Determination of total ash
ISO 930, Spices and condiments — Determination of acid-insoluble ash
ISO 941, Spices and condiments — Determination of cold water-soluble extract
ISO 948, Spices and condiments — Sampling
ISO 3632-1, Spices — Saffron (Crocus sativus L.) — Part 1: Specification
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3632-1 and the following apply.
3.1
moisture and volatile matter content
loss of mass fraction determined under the conditions specified in this part of ISO 3632
NOTE Moisture and volatile matter content is expressed as a percentage mass fraction of the sample.
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3.2
colouring strength
1%
A , 440 nm
1cm
absorbance at the maximum wavelength (about 440 nm) of crocins for a 1 g/100 ml solution of test sample
using a 1 cm quartz cell
NOTE Colouring strength is mainly due to the content of crocins.
3.3
UV-vis profile of saffron extract
spectrum obtained between 200 nm and 700 nm
NOTE An example is given for information in Figure C.1.
3.4
limit of detection
LOD
minimum amount or concentration of the analyte in a test sample which can be detected reliably, but not
necessarily quantified, as demonstrated by a collaborative trial or other appropriate validation
3.5
minimum required performance limit
MRPL
minimum content of an analyte in a sample, which at least has to be detected and confirmed
4 Tests and sample sizes
4.1 Minimum mass of the laboratory sample
Sampling methods for spices and condiments are specified in ISO 948.
Considering the high cost of saffron, the mass of sample received in the laboratories for carrying out the tests
is often limited. The minimum mass of the laboratory sample shall be 23 g (11,5 g × 2) for saffron filaments
and cut filaments and 13,5 g (6,75 g × 2) for saffron powder in order to carry out the standard analyses in
duplicate.
It is recommended that larger quantities of sample be placed at the disposal of the laboratories in case of
dispute.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
4.2 Tests required and test sample sizes
See Table 1 for saffron in filaments, cut filaments and Table 2 for saffron in powder.
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ISO 3632-2:2010(E)
Table 1 — Saffron in filaments and cut filaments forms
Test
Analysis Procedure Corresponding
sample Comments
step (laboratory sample: 11,5 g × 2 = 23 g) clause
g
New test sample
1 Identification test 5 5
Non-destructive test
2 Microscopic examination 0,05 Test sample from step 1 6
Test sample from step 1
3 Determination of floral waste content 3 8
Non-destructive test
Test sample from step 3
4 Determination of foreign matter 3 9
Test sample is reconstituted after
reincorporating floral waste
Determination of extract soluble in
5 2 Test sample from step 4 11
cold water
New test sample
Determination of moisture and
Keep the test sample for
6 2,5 7
volatile matter content
determination of total ash and acid-
insoluble ash
7 Determination of total ash 2 Remains of the test sample from step 6 12
8 Determination of acid-insoluble ash — Test sample produced after step 7 13
New test sample
Carry out the sieving in accordance
with Clause 10 to obtain a powder of
which 95 % mass fraction passes
9 Crushing and sieving 4 10
through a 500 µm sieve.
Reincorporate whatever remains on
the sieve in the receptacle of the
sieve
10 Determination of main characteristics 0,5 Test sample from step 9, after sieving 14
Test sample from step 9, before
sieving
Thin-layer chromatography (TLC):
HPLC (step 12) may alternatively or
11 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 9, before
sieving
High performance liquid
TLC (step 11) may alternatively or
12 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both
methods
NOTE There remain 4,50 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
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Table 2 — Saffron in powder form
Test
Analysis Procedure Corresponding
sample Comments
step clause
(laboratory sample: 6,75 g × 2 = 13,5 g)
g
New test sample
1 Identification test 0,2 5
Do not continue with the analysis if
the colorimetric analysis is not correct
2 Microscopic examination 0,05 New test sample 6
New test sample
Determination of moisture and volatile
Keep the test sample for
3 2,5 7
matter content
determination of total ash and acid-
insoluble ash
4 Determination of total ash 2 Remains of the test sample from step 3 12
5 Determination of acid-insoluble ash — Remains of the test sample from step 4 13
New test sample
Verify that 95 % mass fraction of the
powder passes through a 500 µm
6 Crushing and sieving 4 10
sieve. Reincorporate whatever
remains on the sieve in the receptacle
of the sieve
Determination of extract soluble in cold
7 2 Test sample from step 6 11
water
8 Determination of main characteristics 0,5 Test sample from step 6, after sieving 14
Test sample from step 6, before
sieving
Thin-layer chromatography (TLC):
HPLC (10) may alternatively or
9 0,5 15
identification of artificial colorants
additionally be performed. In the latter
case, use the extract for both
methods
Test sample from step 6, before sieving
High performance liquid
TLC (9) may alternatively or
10 chromatography (HPLC): 0,5 16
additionally be performed. In the latter
identification of artificial colorants
case, use the extract for both methods
NOTE There remain 1 g laboratory sample which can be used for further tests or to repeat certain analyses if necessary.
5 Identification test
5.1 General
This preliminary test may make the subsequent analyses unnecessary if it shows that the saffron is not pure.
5.2 Saffron in filaments and cut filaments
5.2.1 Principle
The saffron is examined visually with a magnifying glass.
5.2.2 Apparatus
5.2.2.1 Magnifying glass, with a magnification of 10 times max.
5.2.2.2 Watch glass, of suitable size.
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5.2.3 Procedure
Spread out the test sample of saffron in filaments and cut filaments (Table 1) on the watch glass (5.2.2.2) and
examine it with the magnifying glass (5.2.2.1).
5.2.4 Interpretation of results
All the filaments shall belong to the plant Crocus sativus L.
Reject the sample if vegetable matter other than that belonging to Crocus sativus L. is found.
5.3 Saffron in powder form
5.3.1 Principle
A colorimetric reaction is used.
5.3.2 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent quality.
5.3.2.1 Sulfuric acid, mass concentration 1,19 g/l.
5.3.2.2 Diphenylamine solution. Add 0,1 g diphenylamine to 20 ml sulfuric acid (5.3.2.1) and 4 ml water.
The diphenylamine shall not produce any coloured reaction with the sulfuric acid.
5.3.3 Porcelain dish, with flat bottom.
5.3.4 Procedure
Use the 0,2 g test sample of saffron (see Table 2) as test portion.
Gradually add the test portion to the porcelain dish (5.3.3) containing the diphenylamine solution (5.3.2.2).
5.3.5 Interpretation of results
Pure saffron immediately produces a blue colour, which rapidly turns reddish brown.
In the presence of nitrates, the blue colour persists.
6 Microscopic examination of saffron
6.1 General
The method is applicable to the examination of saffron in powder, filaments, and cut filament forms in order to
determine whether the sample consists exclusively of stigmas belonging to Crocus sativus L. and to highlight
any floral waste and foreign matter.
6.2 Principle
The identity of saffron in powder and crushed filament form is verified. Foreign matter and floral waste, if any,
are identified by the observation of anatomical elements by using microscopy under the conditions described in
6.5. The percentages relating to the observed elements may be determined if required (see Annexes A and B).
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6.3 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and distilled or
demineralized water or water of equivalent purity.
6.3.1 Iodine in iodide solution, aqueous solution of iodine in potassium iodide.
In a 100 ml one-mark volumetric flask (6.4.5), equipped with a glass stopper, add 2 g iodine, 4 g potassium
iodide, and about 10 ml water. Leave until completely dissolved, then make up to the mark with water. Stopper
the flask.
6.3.2 Illuminating solution, either sodium hydroxide or potassium hydroxide at a mass concentration of
5 g/100 ml water or chloral hydrate with 80 g/100 ml water; dissolve when hot.
6.4 Apparatus
Usual laboratory equipment and in particular the following.
6.4.1 Slides.
6.4.2 Cover-glasses.
6.4.3 Scalpel.
6.4.4 Lancet needles.
[4]
6.4.5 One-mark volumetric flask, capacity 100 ml, ISO 1042 class A.
6.4.6 Syringe, graduated in microlitres, capable of delivering volumes of 50 µl.
6.4.7 Microscope, permitting observation with a magnification of 100 times and 400 times, optionally
equipped with a device permitting observation in polarized light.
6.5 Procedure
6.5.1 Test portion
For each slide (6.5.2 to 6.5.4), take a test portion of the order of 0,001 g to 0,002 g saffron in powder
(see 10.3) or crushed filament (see 10.2) form.
6.5.2 Preparation for observation in water
Prepare two slides as follows.
Deposit 50 µl of water on a slide. Using the tip of a scalpel or lancet needle, take the test portion (6.5.1), mix it
with the water and wait for at least 5 min to ensure that the powder is adequately wet before covering with a
cover slide.
6.5.3 Preparation for observation in an aqueous solution of sodium hydroxide, potassium hydroxide
or chloral hydrate
Prepare two slides as indicated in 6.5.2, but replace water with the sodium hydroxide, potassium hydroxide or
chloral hydrate aqueous solutions (6.3.2).
Wait for a few minutes for the medium to illuminate and observe for 10 min after adding the illuminating
solution in order to avoid altering the cellular elements and ensuring they can be identified.
NOTE This observation enables illumination of the preparations by destroying totally or partially the major part of the
cellular contents. The cellular elements are also made clearer and easier to observe, particularly the sclerous elements,
vessels, fibres and epidermis.
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6.5.4 Preparation for observation in aqueous iodine in iodide solution
Prepare a slide as indicated in 6.5.2, but replace the water with iodine in iodide solution (6.3.1).
NOTE This observation makes visible the starch grains which are stained blackish blue or blackish violet.
6.5.5 Observation, identification, and counting
Place each slide, prepared according to 6.5.2 to 6.5.4, under the microscope (6.4.7). Set the magnification at
100 times. Identify and count the elements observed with a magnification of 400 times (see 6.7).
NOTE The anatomical structures and exogenous elements are identified and counted for each slide on an
observation of 10 fields.
If the microscope used (6.4.7) is equipped with a device permitting observation in polarized light, one of the
two slides prepared in 6.5.2 should be so observed.
Figure 1 shows an example which summarizes all operations permitting counting.
Key
A field
B slide
Figure 1 — Example of counting procedure
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6.6 Expression of results
An example is given for information in Annex A.
6.7 Microscopic examination
See reference photographs given for information in Annex B.
During the examination, the following elements can be observed:
a) fragments of the top extremity of the stigmas with large hair-like elongated papillae, after crushing the
isolated papillae (Figure B.1);
b) epidermic debris of the stigmas which are characterized by small intussusceptions of the membrane
(Figure B.2);
c) debris of the epidermis of the style, characterized by a sinuous wall (Figure B.3);
d) round pollen grains with a diameter of between 80 µm and 100 µm, with a smooth cell wall and finely
granular exine (Figure B.4);
e) fragments of conductor elements made up of spiralled vessels (Figure B.5);
f) fragments of stamens (Figure B.6);
g) grains of starch (Figure B.7);
h) inorganic matter (Figure B.8);
i) fragments of straw (Figure B.9);
j) cells the content of which remain coloured despite the illuminating solution (Figure B.10).
6.8 Interpretation of microscopic observations
Evaluation of the relative percentage of each structure evaluated from the count table permits a check that the
crushed saffron is mainly made up of fragments of stigmas to which fragments of styles and grains of pollen
can be associated.
The observation should be reported in accordance with Tables A.1 and A.2.
NOTE The crushed saffron does not have sclerous cells, fibres, covert hair or starch grains. The contents of the cells
dissolve in water to give an orange-yellow colour.
7 Determination of moisture and volatile matter content
7.1 General
This method is applicable to saffron in filaments, cut filaments and in powder forms.
[3]
NOTE The method of determination of the moisture content of spices and condiments described in ISO 939 is not
applicable in the case of saffron because it requires the use of too large a test portion.
7.2 Principle
The sample is oven dried at 103 °C ± 2 °C for 16 h.
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7.3 Apparatus
Usual laboratory apparatus and in particular the following.
7.3.1 Weighing dish or evaporating dish, provided with a lid or shoe glass.
7.3.2 Oven, capable of being maintained at 103 °C ± 2 °C.
7.3.3 Desiccator, containing an effective desiccant.
7.3.4 Analytical balance, capable of being read to the nearest 0,001 g.
7.4 Procedure
7.4.1 Test portion
7.4.1.1 Saffron in filaments and cut filaments
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 1) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.1.2 Saffron in powder form
Weigh, to the nearest 0,001 g, approximately 2,5 g of sample (see Table 2) into the weighing dish or
evaporating dish (7.3.1) previously dried and tared to the nearest 0,001 g.
7.4.2 Determination
Place the weighing dish or evaporating dish containing the test portion (7.4.1.1 or 7.4.1.2) uncovered in the
oven (7.3.2) maintained at 103 °C and leave for 16 h. Cover with the lid or shoe glass, and allow it to cool in
the desiccator (7.3.3). After cooling, weigh to the nearest 0,001 g.
Conserve the product for the later determination of total ashes (see Clause 12) and acid-insoluble ash (see
Clause 13).
Carry out two determinations on the same laboratory sample.
7.5 Expression of results
The moisture and volatile matter content, w , expressed as a percentage of the initial sample is equal to:
MV
100
wm=−m× %
()
MV 0 4
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the dry residue.
4
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
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8 Determination of floral waste content of saffron in filaments and cut filaments
8.1 Principle
The floral waste present in a test portion is physically separated then weighed.
8.2 Apparatus
8.2.1 Watch glass.
8.2.2 Small laboratory tongs.
8.2.3 Analytical balance, capable of weighing to the nearest 0,01 g.
8.3 Procedure
8.3.1 Test portion
Weigh, to the nearest 0,01 g approximately 3 g of the test sample.
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
8.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs (8.2.2), separate the
different components of floral waste. Weigh on the analytical balance (8.2.3) to the nearest 0,01 g the
previously dried watch glass (8.2.1).
Transfer the separated floral wastes to the shoe glass and weigh the whole to the nearest 0,01 g.
8.4 Expression of results
The floral waste content of the sample, w , expressed as a percentage by mass, is equal to:
F
100
wm=−m× %
()
F2 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the shoe glass containing the floral waste.
2
Take as the result, the arithmetic mean of the two determinations, if the repeatability conditions are met.
9 Determination of foreign matter content of saffron in filaments and cut filaments
9.1 Principle
The foreign matter present in a test portion is separated physically then weighed.
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9.2 Apparatus
Use the same apparatus as specified in Clause 8.
9.3 Procedure
9.3.1 Test portion
Since the mass of the test portion is low, it is advisable that it be taken from a homogenized sample.
Reconstitute the test sample (approx. 3 g) by reincorporating the floral wastes previously separated and
determined as in Clause 8, for saffron filaments and cut filaments. Homogenize well and then weigh the
sample to the nearest 0,01 g.
9.3.2 Determination
Spread the test portion on a sheet of neutral grey paper. With the help of the small tongs, or with other
appropriate means, separate the foreign matter from the test portion.
Weigh, to the nearest 0,01 g, the previously dried shoe glass.
Transfer the separated foreign matter to the shoe glass and weigh the whole to the nearest 0,01 g.
9.4 Expression of results
The foreign matter content of the sample, w , expressed as a percentage by mass, is equal to:
FM
100
wm=−m× %
()
FM 3 1
m
0
where
m is the mass, in grams, of the test portion;
0
m is the mass, in grams, of the shoe glass;
1
m is the mass, in grams, of the watch glass containing the foreign matter.
3
10 Crushing and sieving of the samples for tests described in Clauses 6, 14, 15
and 16
10.1 Apparatus
10.1.1 Crusher, which shall:
a) be easy to dismantle and to clean, and have a minimum dead space;
b) permit a quick and uniform crushing without causing heat or loss of moisture;
c) avoid contact with the ambient air as much as possible;
d) permit a total recovery of all fragments of the sample;
e) not introduce any foreign substance into the sample.
[1]
10.1.2 Sieve, of 500 µm mesh, ISO 565 .
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10.2 Saffron in filaments and cut filaments
Crush the test sample (see Table 1) using the crusher (10.1.1) until 95 % mass fraction of the powder passes
through the sieve (10.1.2).
Then, reincorporate the material remaining on the sieve and homogenize the whole.
10.3 Saffron in powder form
Sieve the test sample (see Table 2) using the sieve (10.1.2) in order to verify that 95 % mass fraction of the
powder passes through it.
If this is not the case, crush the powder in the crusher (10.1.1) to obtain the required particle size.
Then, reincorporate the material remaining on the sieve and homogenize the whole.
11 Determination of extract soluble in cold water
Proceed in accordance with the method given in ISO 941.
For saffron in filaments, cut filaments and in powder forms, take a test portion of 2,00 g ± 0,01 g.
12 Determination of total ash
Proceed in accordance with the method given in ISO 928.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the moisture content (7.4.2).
13 Determination of acid-insoluble ash
Proceed in accordance with the method given in ISO 930.
For saffron in filaments, cut filaments and in powder forms, use the sample which was used for the
determination of the total ash (Clause 12).
14 Determination of the main characteristics using a UV-vis spectrometric method
14.1 General
This method enables the determination of the main characteristics of saffron connected with picrocrocin,
safranal and crocin content. It is directly applicable to saffron in powder form provided that the powder
conforms to the requirements of 10.3 and to saffron filaments and cut filaments after crushing and sieving in
accordance with 10.2.
14.2 Principle
Measurement of the variation in optical density between 200 nm and 700 nm of an aqueous extract of saffron
at ambi
...
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