ISO/PRF TR 29263

Cereals and cereal products -- Sampling studies

Céréales et produits céréaliers -- Études sur l'échantillonnage

General Information

• Status: Published
• ICS: 67.060 - Cereals, pulses and derived products
• Technical Committee: ISO/TC 34/SC 4 - Cereals and pulses
• Drafting Committee: ISO/TC 34/SC 4 - Cereals and pulses
• Current Stage: 5060 - Close of voting Proof returned by Secretariat
• Start Date: 20-May-2021
• Completion Date: 20-May-2021

Standards Content (sample)

TECHNICAL ISO/TR
REPORT 29263
First edition
Cereals and cereal products —
Sampling studies
Céréales et produits céréaliers — Études sur l'échantillonnage
PROOF/ÉPREUVE
Reference number
ISO/TR 29263:2021(E)
ISO 2021
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ISO/TR 29263:2021(E)
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ISO/TR 29263:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Context ............................................................................................................................................................................................................................ 1

5 Study n°1: extract from "Grain sampling and assessment: sampling grain in lorries"

– Project report n° 339” ................................................................................................................................................................................. 1

5.1 General ........................................................................................................................................................................................................... 1

5.2 Context ........................................................................................................................................................................................................... 1

5.3 Studies conducted and objectives........................................................................................................................................... 3

5.4 Methodology ............................................................................................................................................................................................. 3

5.4.1 Conducting tests ............................................................................................................................................................... 3

5.4.2 Results and conclusions .................. ......................................................................................................................... .. 5

6 Study n°2: extract from "Sampling grain in static and flowing condition –

alternatives to the regulatory protocol" ...................................................................................................................................19

6.1 General ........................................................................................................................................................................................................19

6.2 Context ........................................................................................................................................................................................................20

6.2.1 Regulatory aspect .........................................................................................................................................................20

6.2.2 Normative aspect ..........................................................................................................................................................20

6.3 Studies conducted and objectives........................................................................................................................................20

6.3.1 Study A ...................................................................................................................................................................................20

6.3.2 Study B ...................................................................................................................................................................................21

6.4 Study A: silos and lorries of wheat and corn – Fusariotoxins and quality assessment .........21

6.4.1 Organising field tests .................................................................................................................................................21

6.4.2 Results and conclusions .................. ........................................................................................................................33

6.5 Study B : silos of corn – Fusariotoxins; flowing grains ......................................................................................48

6.5.1 Organising field tests .................................................................................................................................................48

6.5.2 Results and conclusions .................. ........................................................................................................................49

7 Study n°3: extract from "Investigation of the distribution of deoxynivalenol and

ochratoxin a contamination within a 26-T truckload of wheat kernels" – Project report ....90

7.1 Context ........................................................................................................................................................................................................91

7.2 Methodology ..........................................................................................................................................................................................91

7.2.1 Instruments for sampling and sample homogenization process ........................................91

7.2.2 Reagents and materials ...........................................................................................................................................91

7.2.3 Sampling procedure ...................................................................................................................................................92

7.2.4 Sample comminution ................................................................................................................................................93

7.3 Results and Discussion ..................................................................................................................................................................93

7.3.1 Distribution of DON and OTA infected kernels within the lot ................................................93

7.3.2 Sample comminution study for the dry milling process.............................................................95

7.4 Uncertainty comparison on the basis of number of incremental samples ......................................95

7.5 Conclusions .............................................................................................................................................................................................97

Bibliography .............................................................................................................................................................................................................................98

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ISO/TR 29263:2021(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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following

URL: www .iso .org/ iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 4,

Cereals and pulses, in collaboration with the European Committee for Standardization (CEN) Technical

Committee CEN/TC 338, Cereal and cereal products, in accordance with the Agreement on technical

cooperation between ISO and CEN (Vienna Agreement).

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO/TR 29263:2021(E)
Introduction

This document presents the results of three groups of studies which results have been used to elaborate

ISO 24333

These studies have been managed by United Kingdom in May 2003, by France in 2004-2005 for the first

one and 2006-2007 for the second one and Germany in 2008.
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TECHNICAL REPORT ISO/TR 29263:2021(E)
Cereals and cereal products — Sampling studies
1 Scope

This document presents the description and the results of the three studies conducted by United

Kingdom, France and Germany related to grain sampling in order to define a harmonized sampling

protocol for official controls.
These results had been used to draft ISO 24333.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Context

European directives for official controls of some contaminants such as mycotoxins required methods

for sampling and analysis. In order to harmonize sampling procedures necessary for these analysis and

to determine the best way to prepare a homogenous and representative laboratory sample, studies had

been conducted by United Kingdom, France and Germany.
The results of these 3 studies are presented in this report.
5 Study n°1: extract from "Grain sampling and assessment: sampling grain in
lorries" – Project report n° 339”
5.1 General
By J. KNIGHT, R. WILKIN and J. RIVETT

Department of Environmental Science and Technology, Renewable Resources Assessment Group,

Imperial College of Science and Technology, Prince Consort Road, London SW7 2BB

This is the final report of a 13-month project that started in May 2003. The work was funded by HGCA

(project 2955).
5.2 Context

This two-year programme was made at the request of HGCA to improve and standardise grain sampling

and analysis across the UK cereals industry.
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The first phase of the programme was to develop and validate protocols suitable for collecting samples

of grain on UK farms at harvest time and to train farmers in their use. The second part was to examine

approaches to the collection of samples during storage and to compare the results obtained, wherever

possible, with data collected as the store was filled. During the course of earlier sampling work, there

was strong interest expressed in the mechanics and effectiveness of sampling loads of grain in lorries.

In addition, some of the work done during storage involved sampling grain as it left the store in lorries.

This showed up the limitations of some approaches to lorry sampling and highlighted the need for more

information. An assessment of lorry sampling was therefore, added and is reported here.

Almost all grain is sampled as it is delivered to end users to confirm its quality and to ensure that

contractual obligations are met. This sampling takes the form of collecting one or more samples from a

lorry-load on arrival. The equipment used and method of sampling varies between end users and there

are no data to show if these variations may cause bias in the representativeness of the sample and,

therefore, in the results of quality analysis.

The key aim of end-user sampling is to ensure that the quality of the grain is suitable for its intended

use. Therefore, sampling is done before the load is tipped and this limits access to the surface of the

load. This access is further constrained by food safety and HSE legislation that prevent the sampler

from walking on the load.

A limited assessment of the practicalities of sampling lorries was done in 1992 (HGCA Project

Report 79) in which the effects of method of sampling, number and position of sample points, the

methods of loading lorries were considered. The wheat sampled was low-grade feed material with a low

specific weight and a high level of fine material so was not representative of other grades. The results

suggested that loading lorries with a front loader or from a hopper had no effect on the distribution of

the quality characteristics within a load. Small differences were noted in the mean values for specific

weight between automatic sampling using a Samplex CS90 and a manual spear but overall variability

of the grain meant that these differences were not significant. There was significant variability in the

results obtained at individual points with either method, although this variability was random and not

associated with any part of the load. Fine material appeared to be very difficult to measure. At the time,

this work was undertaken there were no restrictions limiting access to the surface of the grain so that a

widely disbursed pattern of sampling points could be used with the manual sampling. The conclusions

from this work were that it was extremely unwise to base an assessment of lorry load of grain on a

single sample and that more work was needed to confirm the results and to assesses other grades of

grain. The aim of this project was to establish if there are any inherent problems with the sampling of

grain for the determination of quality characteristics in lorries at the point of intake and to establish

recommendations in the form of a protocol for the sampling of grain under these conditions.

Grain was sampled using automated systems (Samplex CS90) and manual spearing to see if the method

of sampling influenced the grain quality measurements. A key part of the process was to assess the

influence that the number of samples taken from each load had on the likely accuracy of the results.

Samples were collected at 4 different locations; on two occasions 10 lorries were sampled and on two

occasions 8 lorries were sampled. At three locations, CS90 samplers were used and 8 samples were

withdrawn from each load and at the other location samples were taken manually with a multi-

compartmented spear with 5 samples being taken from each lorry. A comparison of different ways

of sample handling was obtained by comparing the individual results from the 8 samples against an

analysis of samples withdrawn from a composite sample formed from 8 samples. The latter method

reflects more accurately the procedure followed at most stores.

Results indicated that there were no statistically significant differences between results from the

individual samples or from the composite samples. Monte Carlo simulation of the impacts of using 2, 3, 5

or 8 samples per load revealed that the greater the number of samples used the greater the reliability of

the result and the more likely it was to represent the true mean of the load. It was noted that automatic

sampling equipment can no longer sample the entire length of a trailer and this could cause problems

with obtaining the ideal sample. Manual sampling also had severe limitations due to the lack of safe

access for sampling of trailers.

A sampling protocol for lorries is presented which emphasises the need for 8 samples to be taken from

each load in order to get a good representation of the quality of the entire load.

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5.3 Studies conducted and objectives

The study was conducted to assess the effectiveness of different approaches to sampling loads of grain

in lorries.
The specific objectives were:

— To assess if the method of collecting samples influences grain quality measurement;

— To assess if the number and position of sampling points influences grain quality measurement;

— To provide guidelines for sampling lorries giving reliable information about grain quality.

5.4 Methodology
5.4.1 Conducting tests
5.4.1.1 Collection of data relating to current sampling practice

In November 2002 the HGCA circulated a questionnaire to commercial grain stores and end-users of

grain requesting information about their methods of analysis and methods of intake sampling. The

information that was collected was used to assist with the design of the assessment of lorry sampling.

5.4.1.2 Sample collection
5.4.1.2.1 Store 1

The work was done at a store specialising in the storage of malting barley. Lorries were loaded with

malting barley, variety Pearl, of a quality representative of that delivered to central storage from farms.

The lorries, all 28 t articulated units, were loaded with a front loader fitted with a 2 t bucket.

Ten loads were sampled over a 2-day period. Sampling was done using the store’s Samplex CS90

automated vacuum sampler. Initially, it had been expected to re-programme the CS90 to take 10

samples/load in a pre-set pattern. However, observation of the method of operation and sampling

pattern achieved by the CS90 suggested that there was no advantage in using more than the 8 points

provided by one of the standard sampler programmes.

During the setting up and initial testing of the CS90, the slide on the sample spear was opened to its

maximum to increase the sample size. The system was set to collect grain only during the withdrawal

as is recommended by the manufacturer for granular materials.

Each of the eight points was sampled three times. On the first occasion, individual samples were held

separately. During the second and third samplings, all samples were bulked into single batches. One of

these bulk samples was held as a composite sample and the other was used to provide samples of 1, 2

and 3 litres (small medium and large) collected at random with a 1-litre jug.

A small sub-sample from each of the individual samples was tested on the spot by store staff for

screenings and germinative capacity. Screenings were tested by sieving a 100 g sub-sample with

a motorised shaker fitted with a 2,25 mm mesh screen for 2 minutes. The germinative capacity was

tested using the standard tetrazolium test.
5.4.1.2.2 Store 2

Work was done at a commercial store during the normal out-loading of feed wheat. The lorries were

loaded from an on-floor bulk using a front-bucket loader and were sampled as they left the store. Normal

sampling practice was to collect a single spear sample/load using a manual, multi-compartmented spear

of about 1,7 m in length. Access to the load was via a small sampling platform that only allowed samples

to be taken from less than half the length of the loaded trailer and from only one side of the load.

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For the purposes of this investigation, 5 sample points were used for each load and the lorry was moved

forward during the sampling process so that access to the whole length of the load could be obtained.

However, it was not practical to turn the lorry round to give access to both sides of the load. Manual

sampling meant that there was, inevitably, some variation in the exact location of the sample points

between loads. Three spear samples were collected at each point. The first was held as an individual

sample, the second bulked to form a composite sample and the third bulked to give a sample from which

three random samples (small, medium and large) could be taken without mixing.
Ten lorry loads were sampled over a two-day period.
5.4.1.2.3 Store 3

The assessments were made at a commercial store during the normal out-loading of milling wheat.

Samples were collected using a Samplex CS90 but without the automatic option. Therefore, the spear

had to be controlled manually by the operator and this meant that there was considerable variation in

the positioning of sample points between loads. A further constraint on sampling was that the CS90

was positioned at one end of the weighbridge thus limiting access to just one-half of the load. The slide

on the sampler was fully open and grain was collected only as the spear withdrew.

The lorries were loaded using a bucket loader from a 2 000 t batch of wheat stored on-floor. Only a

limited number of loads were dispatched each day and time constraints meant that only 8 loads were

sampled during this assessment.

Three samples were collected from 8 sample points in each load. The first was held as an individual

sample, the second bulked to form a composite sample and the third bulked to give a sample from

which three random samples (small, medium and large) could be taken without mixing. The 8 points

were arranged in a 3, 2, 3 pattern with the two samples being taken from the centre line and each row

of 3 taken down the sides of the load (see Figure 1). The location of the sampler and the position of the

lorry on the weighbridge meant that the samples always came from the front half of the load.

Figure 1 — Arrangement of sampling points used by CS90 sampler

Data was supplied by the storekeeper giving the store’s own assessment of the quality of the batch of

grain as measured when the store was filled.
5.4.1.2.4 Store 4

Loads of milling wheat delivered to a large flour mill were sampled with a Samplex automatic CS90.

This work was done some months after the earlier assessments and it was decided that the collection of

extra samples to make up composite batches was not justified. Eight samples were collected from eight

loads of wheat over a 10 d period. For technical reasons, the collection of samples had to be done by mill

staff so the exact details of the points sampled are not known.
5.4.1.3 Assessment of samples

Samples had to be transported to the testing laboratory and some additional delays occurred between

the collection and assessment of samples. However, samples that could not be analysed within 48 h

were stored in a freezer at -16 °C to minimise changes in the properties of the grain. These samples

were allowed to return to ambient temperature before testing. The exceptions to this were samples

collected from store 4.
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These were collected over a 10 d period and a further 4 d elapsed before the samples arrived for testing.

During this period, the samples were not held under controlled temperature conditions.

Individual samples were tested separately, as were the three different sizes of random sample. However,

in the case of the medium and large samples, these were divided by coning and quartering to give the

correct volume of grain for assessment. The composite samples were also mixed and then divided by

coning and quartering. Five sub-samples of the composites were tested from Store1 but only three sub-

samples were tested from stores 2 and 3.

As a first step in the assessment process, the screenings in each sample were measured by manual

sieving. Each sample was weighed and then sieved for 30 s using a 2,5 mm slotted sieve for wheat or a

2,25 mm slotted sieve for barley. The sievings were weighed and the percentage calculated. The weights

of the individual samples gave an indication of the variation in the size of sample collected on each

occasion.

After sieving, the properties of each sample were assessed using a Foss Infratec Grain Analyser 1241

GA-TWM . The machine used official calibrations as provided by the NIR network and measured

moisture content, specific mass, protein in the case of wheat, or nitrogen in the case of barley and made

an assessment of hardness of wheat.

In addition, some of the samples of wheat from stores 2 and 3 were sent to NIAB for assessment of

Hagberg Falling Number. Complete sets of individual samples from 5 loads, together with a single

composite sample were tested from Store 3. Complete sets of individual samples and a single composite

from 4 loads were tested from Store 2. The testing was done using standard methodology and each

result was the mean of two determinations.
5.4.1.4 Estimating the reliability of sampling

The impact of the number of samples taken on the reliability of the result obtained from those samples

was assessed by determining the mean and standard deviation for the results of the 8 samples taken

from each lorry. This information was used to define a probability curve for a normal distribution for

each of the lorries. A Monte Carlo simulation was then run to sample from either 2, 3, 5 or 8 of these

distributions depending on the sampling regime to be simulated. The simulation was run for a total of

100 000 trials. From this result, cumulative probability distribution curves were obtained and these

were used to estimate the confidence limits for different numbers of samples for a given margin of

error. Thus, the confidence interval for sampling 2, 3, 5, or 8 times for a known deviation from the mean

for the different quality parameters could be produced. The final figure shows the probability of the

confidence interval actually covering the mean value.
5.4.2 Results and conclusions
5.4.2.1 Sample analysis results
5.4.2.1.1 Collection of data relating to current sampling practice

As part of the initiative to standardise grain testing a survey of laboratory practice was undertaken

and this included a set of questions on the collection of samples from lorry-loads of grain. This provided

information from a range of commercial premises receiving, handling or processing grain about current

lorry sampling practices. The response showed that there was no common industry-wide approach.

The most frequently used equipment was the Samplex CS90 or other unspecified Samplex units (49 %)

followed by manual sampling (37 %). The number of samples collected per load ranged between 1 and

10 and the mass of grain collected varied between 0,4 kg and 11 kg.

1) Foss Infratec Grain Analyser 1241 GA-TWM is an example of a suitable product available commercially. This

information is given for the convenience of users of this document and does not constitute an endorsement by ISO

of thisproduct.
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5.4.2.1.2 Observations on the sampling
5.4.2.1.2.1 Store 1

During the assessment, it became apparent that the reach of the CS90 sampling arm and the size of

current a
...