AS 5013.28:2009 pdf – Food microbiology Method 28: Examination of specific products—Liquid milks and creams

AS 5013.28:2009 pdf – Food microbiology Method 28: Examination of specific products—Liquid milks and creams.
Completely immerse a screw-capped glass test tube or glass McCartney bottle holding 10 niL of sample. in water maintained at 63.5 0.5°C in a thermostatically controlled sater bath titled with a suitable agitator. The temperature of the sample shall reach 63°C within 5 mm. After a further 30 mm. remove the tube or bottle from the water bath and immediately cool to 5°C or below in iced water. In placing the container in the cooling water. avoid wetting the closure but ensure that the kvel of the water is above the level of the milk or cream. Upon removal from the iced water, wipe the tube or bottle with a tissue.
8.2 Colony count
Use the pour plate method described in AS 5013, using plate count agar and incubating at
30 ±1°C for 72 ±2 h.
9 PHOSPHATASE TEST FOR PASTEURIZED MILK AND CREAM
Carry out the phosphalase test in accordance with AS 2300.1.10. directly on the chilled. undiluted sample.
NOTE: After pasteurization, reactivation of phosphatase in cream can occur. Care should therefbre be exercised in the interpretation of results.
10 TEST REPORT
The following information shall be reported:
(a) All details necessary for the complete identification of the sample.
(b) Reference to this Australian Standard. i.e. AS 5013.28.
(c) Date of testing.
(d) Any abnormality observed in the physical condition of the container or the product.
(e) Results of the tests.
(f) Any circumstance or conditions that may have influenced the results.
A2 DEFINITIONS
For the purpose of this Standard, the definitions below apply.A2.1 Microbial clump count
Microbial count based on groups of microorganisms which appear to be the same type: cellof like kind within 5 um of a group are deemed to belong to that group，regardless ofcloseness to each other, cells of different types are deemed to be separate clumps.
A2.2 Individual count
Microbial count of all individual cells, both within groups and in isolation.A3 REAGENTS
A3.1 Methylene blue staining solution (modification of Newman Lampert Stain)
Add，gradually,0.5 g of methylene blue chloride (certified grade) to a mixture of 56 mL95 percent ethanol and 40 mL xylene (technical grade) in a stoppered 200 mL flask.Dissolve by swirling the flask. Stand overnight (12 h to 24 h) under refrigeration(0°C to 4C). Filter through fine paper* and add 4 mL glacial acetic acid to filtrate. Store ina tightly closed bottle in a cool dark place.