ASTM D7819-12

Standard Test Method for Enumeration of Yeast and Mold on Fresh (Uncured) Hides and Skins

SIGNIFICANCE AND USE
4.1 This test method enumerates yeast and mold. Yeast and mold have been known to cause damage to hides and skins.
SCOPE
1.1 This test method covers the enumeration of yeast and mold on fresh (uncured) hides and skins. This test method is applicable to uncured hides and skins.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Aug-2012
• ICS: 07.100.99 - Other standards related to microbiology
• Technical Committee: D31 - Leather
• Drafting Committee: D31.02 - Wet Blue

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7819 − 12
StandardTest Method for
Enumeration of Yeast and Mold on Fresh (Uncured) Hides
and Skins
This standard is issued under the fixed designation D7819; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 5. Apparatus
1.1 This test method covers the enumeration of yeast and 5.1 Incubator, 20–25°C.
mold on fresh (uncured) hides and skins. This test method is
5.2 Colony counter (not mandatory, but highly recom-
applicable to uncured hides and skins.
mended).
1.2 The values stated in SI units are to be regarded as
5.3 Sterile pipets.
standard. No other units of measurement are included in this
5.4 Stomacher, for mixing initial dilution. [If stomacher is
standard.
unavailable, hand-mix.]
1.3 This standard does not purport to address all of the
5.5 Balance.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5.6 Sterile petri dishes.
priate safety and health practices and determine the applica-
5.7 Autoclave (sterilizer). (Check the effectiveness of ster-
bility of regulatory limitations prior to use.
ilizationweekly.Forexample,placesporesuspensionsorstrips
of Bacillus stearothermophilus(commerciallyavailable)inside
2. Referenced Documents
glassware for a full autoclave cycle. Follow manufacturer’s
2.1 ASTM Standards:
directions for sterilization of specific media.)
D6715Practice for Sampling and Preparation of Fresh or
5.8 pH meter.
Salt-Preserved (Cured) Hides and Skins for Chemical and
Physical Tests
5.9 Waterbath, 45 6 1°C.
E691Practice for Conducting an Interlaboratory Study to
5.10 Stomacher bags, or sterile, sealable quart plastic bag
Determine the Precision of a Test Method
(e.g. Food storage type, sterile bag).
E177Practice for Use of the Terms Precision and Bias in
5.11 Cutting tool, sterile (e.g. scalpel blade and forcep, as
ASTM Test Methods
needed for cutting cured hides and skins).
3. Summary of Test Method
5.12 Vortex mixer, for mixing dilution tubes (optional).
3.1 Samples of uncured hides and skins are serially diluted
5.13 Autoclave thermometer, or equivalent for monitoring
andplatedonagarcontaininganantibioticsolution.Theplates
autoclave temperature.
are incubated at 20–25°C for 5 days.
6. Reagents and Materials
4. Significance and Use
6.1 Butterfield’s Phosphate Stock Solution: Dissolve 34 g
4.1 This test method enumerates yeast and mold. Yeast and
KH PO (Potassium Phosphate monobasic) in 500 mL DI
2 4
mold have been known to cause damage to hides and skins.
water.Adjust the pH to 7.2 6 0.1 with 1N – 6N NaOH. Bring
volume to 1 L with DI water. Sterilize for 15 min at 121°C.
NOTE 1—Typical autoclave setting is 120–124°C at 15 psi. (See 5.7.)
ThistestmethodisunderthejurisdictionofASTMCommitteeD31onLeather
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
6.2 Butterfield’s Phosphate Diluent (BPD):Take1.25mLof
Current edition approved Sept. 1, 2012. Published October 2012. DOI: 10.1520/
Butterfield’s Phosphate Stock solution (6.1) and bring to 1 L
D7819-12
For referenced ASTM standards, visit the ASTM website, www.astm.org, or with DI water. Dispense into 1 litre bottles and 9 mL dilution
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
tubes. Sterilize for 15 min at 121°C. (See Note 1.)
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 6.3 Potato Dextrose Agar (PDA).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7819 − 12
6.4 Antibiotic solution (Chloramphenicol ) – (needed to 9.3 Add 10 mL of chloramphenicol stock solution per litre
inhibit bacterial growth on agar). of agar to give a concentration of 100 ppm. Sterilize in the
autoclavefor15minat121°C.(SeeNote1.)Coolto45 61°C
6.5 Distilled or deionized water.
inawaterbath.Oncemediumhasbeentempered,itcanbeheld
6.6 NaOH, 1N – 6N.
for 2–3 h before use, provided the water level in the waterbath
6.7 Bacillus stearothermophilus spore suspensions or strips is 2–3 cm above the surface of the agar. Final pH of the agar:
5.6 6 0.2.
(commercially available), or equivalent.
10. Procedure
7. Hazards
10.1 Using a sterile scalpel, aseptically obtain a 20 6 0.1 g
7.1 Allreagentsandchemicalsshouldbehandledwithcare.
specimen that includes both the flesh side and the hair side.
Before using any chemical, read and follow all safety precau-
Weighitintoasterilebag.Add180gofBPD(6.2)diluentinto
tions and instructions on the manufacturer’s label or MSDS
thesamesterilebag.Stomachorhand-massagefor1min.This
(Material Safety Data Sheet).
provides a 1:10 dilution.
8. Sampling
-2 -3 -4
10.2 Preparethefollowingsampledilutions:10 ,10 ,10 ,
-5 -6 -7
8.1 The specimen shall be sampled in accordance with
10 ,10 , and 10 (see Fig. 1).
-2 -1
Practice D6715, and placed in sterile containers.
Example:Toobtaina10 dilution,mixthe10 dilutionand
-1
pipet 1 mL of that 10 dilution intoa9mL dilution tube.
9. Preparation of Potato Dextrose Agar and Antibiotic
NOTE 2—When transferring the aliquots between the tubes, the analyst
Solution
must use a different pipet or pipet tip for each transfer.
9.1 Prepare the Antibiotic stock (10,000 ppm) solution by
10.3 Pipet 1 mL of each dilution into the appropriate,
dissolving1gof chloramphenicol in 100 mLsterile deionized
separate petri dishes.
or distilled water. Store this stock solution in a dark location at
10.4 Pour prepared agar (9.3) that has been previously
≤5°C for up to two months.
tempered to 45 6 1°C into the dish.
9.2 Suspend 39 g of Potato Dextrose Agar in 1 litre of NOTE 3—Add agar within 1–2 min after adding dilution to avoid
adherence of sample to bottom of dish. Do not pour agar directly on the
deionized or distilled water and heat to boiling to dissolve
sample. Replace the cover.
completely.
10.5 Swirltheplategentlyinafigure-eightmotiontoevenly
distribute the sample.
The sole source of supply known to the committee at this time is Sigma-
10.6 Allow agar to solidify.
Aldrich, Cat. # C0378 (25 g). If you are aware of alternative suppliers, please
provide this information toASTM International Headquarters.Your comments will
10.7 Incubate at 20–25°C for 5 days (a cabinet at room
receive careful consideration at a meeting of the responsible technical committee,
temperature is acceptable for use).
which you may attend.
FIG. 1 Plating
D7819 − 12
NOTE4—Donotstackplateshigherthan3,anddonotinverttheplates.
laboratories participated in this study. Each of the two labora-
Let plates remain undisturbed until time for counting. Moving the plates
tories reported seven replicate test results for both the number
coulddislodgesporesthuscrea
...