MFO-11 Microbiological Examination of Cocoa and Chocolate
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774559D500834862AB39EDD6F6C071C5 |
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0.02 |
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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-11,November 30, 1981,HEALTH PROTECTION BRANCH,OTTAWA,MICROBIOLOGICAL EXAMINATION OF COCOA AND CHOCOLATE,1. APPLICATION,This method shall be used for the determination of the bacteria of the genus Salmonella in cocoa and chocolate,in accordance with Section B.04.010 and Section B.04.011, 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 product produced under,essentially the same conditions, at the same establishment and representing no more than one,day's production; or, (b) the quantity of the same kind of product 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of a,minimum of 100 g. A sample unit is often referred to as a subsample.,2.1.4 Analytical Unit: That amount of product withdrawn from the sample unit for analysis.,2.2 Collection of Samples,2.2.1 A sample, consisting of ten sample units drawn at random from each lot, shall be taken.,2.2.2 Each sample unit shall contain 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. When the,lot consists of containers smaller than 100 g, a sample unit will consist of more than one,container (e.g., four 25 g containers in each sample unit).,MFO-11,- 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 ten sample units shall be analyzed individually or as one or more composite(s) 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 at the laboratory.,3.2 Preparation of media,The following media, 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 Prepare a 10% w/v of non-fat-dry-milk solution in distilled water containing brilliant green at a,final concentration of 1:50,000. Sterilize at 121oC and cool to 45oC.,3.3.2 a. Weigh 25 g (the analytical unit) from each sample unit into a separate blender jar and,add 225 ml of non-fat-dry-milk solution, blend for the minimum time required to produce,a homogeneous suspension and transfer the contents to a sterile container. To avoid,overheating, blending time should not exceed 2.5 min.,b. The analytical units may be composited. Suspend the composite units in nine times,their weight of non-fat-dry-milk solution and proceed as in 3.3.2.a.,3.3.3 Check the pH of each blended analytical or composite unit. If the pH is outside the range of 6.0,- 7.0, adjust to 7.0 with either sterile NaOH or HCl.,3.3.4 Inoculate 10ml of the non-fat-dry-milk- solution prepared in 3.3.1, above, 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.,3.3.5 Incubate the inoculated pre-enrichment broth(s) and the controls at 35oC + 0.5o for 18-24 hr. In,no circumstances shall the incubation be prolonged for more than 24 hr.,MFO-11,- 3 - November 30, 1981,3.4 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 broth and TBG broth 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……
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