MFO-12 Microbiological Examination of Milk Powder
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F3F0BD7585B54726B72053DA159101B7 |
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文件大小(MB)： |
0.02 |
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页数： |
6 |
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日期： |
2012-3-2 |
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Published by: POLYSCIENCE PUBLICATIONS, P.O. Box 1606, Station St-Martin, Laval, Quebec,Canada H7V 3P9. TEL.: 1-800-840-5870. FAX:(450) 688-1930.,Government of Canada Gouvernement du Canada,Official Method MFO-12,November 30, 1981,HEALTH PROTECTION BRANCH,OTTAWA,MICROBIOLOGICAL EXAMINATION OF MILK POWDER,1. APPLICATION,This method shall be used for the determination of the bacteria of the genus Salmonella in milk powder, in,accordance with Section B.08.014A. of the Food and Drug Regulations.,2. SAMPLING,2.1 Definition of Terms,2.1.1 Lot: A batch or production unit which may be identified by the same code. When there,is no code identification, a lot may be considered as (a) that quantity of milk powder,produced under essentially the same conditions, at the same establishment and,representing no more than one day's production; or, (b) the quantity of milk powder from,one and the same manufacturer available for sampling at a fixed location.,2.1.2 Sample: The sample units (subsamples) taken per lot for analysis.,2.1.3 Sample Unit: Usually a consumer size container of the product, and should consist of,a minimum of 100 g. A sample unit is often referred to as a subsample.,2.1.4 Analytical Unit: That amount of product withdrawn from the sample unit for analysis.,2.2 Collection of Samples,2.2.1 A sample, consisting of 20 sample units drawn at random from each lot, shall be taken.,2.2.2 Each sample unit shall consist of at least 100 g.,2.2.3 Collect original unopened containers wherever possible.,2.2.4 More than one sample unit may be collected from large institutional or bulk containers,when the total number of sample units required exceeds the number of containers in the,lot. A sample unit will consist of more than one container when the lot consists of,containers smaller than 100 g (e.g., four 25 g containers in each sample unit),MFO-12,- 2 - November 30, 1981,2.2.5 Employ aseptic techniques in collecting the sample units when sampling from bulk.,Place each collected sample unit into a separate sterile container.,3. PROCEDURE,The 20 sample units shall be analyzed individually or as two or more composites for determining the,presence of bacteria of the genus Salmonella.,The test shall be carried out in accordance with the following instructions.,3.1 Handling of Sample units,3.1.1 Analyze the sample units as soon as possible after they have been received in the,laboratory.,3.2 Preparation of Media,The following media, which are to be prepared and sterilized according to the manufacturer's,instructions, shall be used:,(1) Nutrient Broth (NB),(2) Selenite Cystine (SC) broth,(3) Tetrathionate Brilliant Green (TBG) broth,(4) Bismuth Sulfite (BS) agar,(5) Brilliant Green Sulfa (BGS) agar,(6) MacConkey Agar (MA),(7) Triple Sugar Iron (TSI) agar,(8) Lysine Iron (LI) agar,(9) Christensen's Urea (CU) agar,(10) Nutrient Agar (NA),3.3 Non-selective Enrichment (Pre-enrichment),3.3.1 Withdraw a 25 g analytical unit from each 100 g sample unit. When a sample unit,consists of more than 1 container mix the contents of each container of the sample unit,aseptically prior to obtaining the 25 g analytical unit. The analytical units may be,composited.,3.3.2 Resuspend the individual analytical units or the composite unit(s) in nine times their,weight of distilled water.,3.3.3 Add brilliant green solution to obtain a final concentration of 1:50,000.,3.3.4 Shake the container to ensure uniform distribution of the microorganisms present, in the,suspension.,3.3.5 Check the pH of each suspended analytical or composite unit. If the pH is outside the,range of 6.0 to 7.0, adjust to 7.0. with either sterile NaOH or HCL.,3.3.6 Inoculate NB with a known culture of Salmonella, and subsequently make transfers to,all other media used in the analysis. This is the positive media control. Set up a,negative control by incubating appropriate uninoculated media during each step of the,analysis.,MFO-12,- 3 - November 30, 1981,3.3.7 Incubate the inoculated pre-enrichment broth(s) and the controls at 35oC + 0.5o for,18-24 hr. In no circumstances should the incubation be prolonged for more than 24 hr.,3.4 Selective Enrichment,3.4.1 Transfer 1 ml of the incubated pre-enrichment broth into each of 9 ml of SC and TBG,broths using a sterile pipette.,3.4.2 Incubate the SC and TBG broths for 24 + 2 hr at 35oC + 0.5o and at 43oC + 0.5o,respectively.,3.5 Selective Plating,3.5.1 After the incubation period, streak a loopful of each of the selective enrichment broths,onto BS agar* and BGS agar plates to obtain well-isolated colonies. The broths may,also be streaked onto a third commercially available plating medium.,3.5.1.1 It has been……
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