MFO-7 Microbiological Examination of Milk
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C668DCA0F1AA40689034CA57A66499D9 |
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0.01 |
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4 |
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2024-7-30 |
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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: (514) 688-1930.,Government of Canada Gouvernement du Canada,Official Method MFO-7,November 30, 1981,HEALTH PROTECTION BRANCH,OTTAWA,MICROBIOLOGICAL EXAMINATION OF MILK,1. APPLICATION,This method shall be used for the determination of total aerobic bacteria (Aerobic Colony Count) in (naming,the flavour) milk, (naming the flavour) partly (partially) skimmed milk, milk for manufacture into dairy products,(naming the flavour) partly (partially) skimmed milk with added milk solids in accordance with sub-paragraph,(e) of Section B.08.016, sub-paragraph (f) of Section B.08.018, sub-paragraph (a) of Section B.08.024 and,sub-paragraph (g) of Section B.08.026 of the Food and Drug Regulations, respectively.,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 from a lot for analysis.,2.1.3 Sample Unit: Usually a consumer size container of the product, and should consist of a minimum,of 100 ml. A sample unit is often referred to as a subsample.,2.1.4 Analytical Unit: That amount of product withdrawn from the sample unit for analysis.,2.2 Collection of Samples,2.2.1 A sample, consisting of five sample units drawn at random from each lot, shall be taken.,2.2.2 Each sample unit shall consist of at least 100 ml.,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 ml, a sample unit will consist of more than one containers,(e.g., four 25 ml containers in each sample unit).,MFO-7,- 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.,2.2.6 Keep sample units refrigerated (0-5oC) during transport.,3. PROCEDURE,Each sample unit shall be analyzed individually. The tests shall be carried out on the sample in accordance,with the following instructions.,3.1 Handling of Sampling Units,3.1.1 Keep sample units refrigerated (0-5oC) in the laboratory prior to analyzing them.,3.1.2 Analyze the sample units as soon as possible after they have been received at the laboratory.,3.2 Preparation of media,The following medium, to be prepared and sterilized according to the manufacturer's instructions,shall be used:,3.2.1 Plate Count (PC) agar,3.3 Preparation of Dilutions,3.3.1 Prepare sterile 0.1% peptone water diluent.,3.3.2 Thoroughly mix each sample unit by shaking the container.,3.3.3 Prepare a 1:10 dilution of the "milk" by aseptically pipetting 11(10)ml* (the analytical unit) of the,milk into 99(90)ml* of the diluent.,* Weight or volume in brackets indicate alternate procedure for making dilutions.,3.3.4 Mix the 1:10 dilution by shaking the dilution bottle 25 times in a 30 cm arc in approximately 7 sec.,3.3.5 Check the pH of the suspension. If the pH is outside the range of 5.5 to 7.6, adjust to 7.0, with,either sterile NaOH or HCl.,3.3.6 Prepare succeeding dilutions as required to determine the ACC present in the "milk" by,transferring 11(10)ml of the previous dilution into 99(90)ml of 0.1% peptone water diluent. Shake,all dilutions (as in step 3.3.4, above) immediately prior to making transfers to ensure uniform,distribution of the microorganisms present.,3.4 Determination of the ACC,The medium used is PC agar prepared for making pour plates.,3.4.1 Analysis,a. Agitate each dilution bottle to resuspend material.,b. Without delay, pipette 1 ml of each prepared dilution into each of two appropriately,marked Petri plates using a sterile pipette for each transfer.,c. Pour 12-15 ml of tempered agar (40-45oC) into each plate and mix contents by rotating,MFO-7,- 3 - November 30, 1981,and tilting.,d. Allow the agar to solidify.,e. Plates shall be poured not later than 15 min after preparation of dilutions.,f. Incubate plates in an inverted position at 35oC + 0.5o for 48 + 2 hr.,g. Avoid crowding or excessive stacking of plates in order to permit rapid equilibration o……
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