MFO-9 Microbiological Examination of Mineral Water
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DE6913D4FA2240A387CC1C5216AC2DA2 |
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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-9,November 30, 1981,HEALTH PROTECTION BRANCH,OTTAWA,MICROBIOLOGICAL EXAMINATION OF MINERAL WATER,1. APPLICATION,This method shall be used for the determination of coliform bacteria (Coliforms) in mineral water in,accordance with Section B.12.001(b) 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 mineral water,produced under essentially the same conditions, at the same establishment and,representing no more than one day's production; or, (b) the quantity of mineral water,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 A sample unit is often referred to as a subsample.,2.1.4 Analytical Unit: That amount of product withdrawn from the sample unit for analysis.,2.2 Collection of Samples,2.2.1 A sample, consisting of ten sample units drawn at random from each lot, shall be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 Ship and store the sample units under refrigeration (<5oC) if more than 2 hr elapse,between collection and analysis. Do not freeze the sample units.,3. PROCEDURE,Each of the 10 sample units shall be analyzed individually.,MFO-9,- 2 - November 30, 1981,The tests shall be carried out in accordance with the following instructions:,3.1 Handling of Sample Units,Do not store sample units for more than 24 hr before analysis.,3.2 Preparation of Media,The following media, to be prepared and sterilized according to the manufacturer's instructions,shall be used:,3.2.1 Lauryl Sulfate Tryptose (LST) broth,3.2.2 Brilliant Green Lactose 2% Bile (BGLB) broth,3.3 Preparation of Dilutions,The undiluted sample units only are required.,3.4 Presumptive Test,3.4.1 The medium used is LST broth, dispensed in 10 ml volumes into tubes containing gas,vials (inverted Durham tubes).,3.4.2 Arrange LST broth tubes in rows of five, and mark them identifying the sample, the,sample unit and the dilution to be inoculated.,3.4.3 Inoculate each of five tubes of double strength LST broth with 10 ml of the undiluted,sample unit, and inoculate each of five tubes of single strength LST broth with 1 ml of,the undiluted sample unit, and inoculate each of five tubes of LST broth with 0.1 ml of,each undiluted sample unit.,3.4.4 Mix inoculum and medium by gently shaking or rotating the tubes, but avoid entrapping,air in the gas vials.,3.4.5 Incubate the inoculated LST broth tubes at 35oC + 0.5o for 24 + 2 hr. Examine for gas,formation, record results, and on the same day begin the confirmed test for all,gas-positive tubes (see section 3.5, below).,3.4.6 Incubate gas-negative tubes for an additional 24 + 2 hr, examine, record the number,of gas-positive tubes, add to the result obtained in step 3.4.5, above, and begin the,confirmed test for the additional gas-positive tubes.,3.4.7 The absence of gas in all of the tubes at the end of 48 + 2 hr of incubation constitutes,a negative presumptive test.,3.4.8 Compute the "MPN" of presumptive coliforms per 100 ml of mineral water following the,instructions in Part 5, to convert the number of gas-positive tubes to MPN values.,Record results.,3.5 Confirmed Test,3.5.1 The confirmatory medium used is BGLB broth dispensed in 10 ml volumes in tubes,containing gas vials.,3.5.2 Submit all gas-positive LST broth tubes to the confirmed test.,3.5.3 Shake or rotate the LST broth tubes to mix the contents and transfer one loopful from,each positive LST broth tube to a tube of the BGLB broth. (Avoid transferring pellicle).,MFO-9,- 3 - November 30, 1981,3.5.4 Mix inoculum and medium by gently shaking or rotating the tubes, but avoid entrapping,air in the gas vials.,3.5.5 Incubate the inoculated BGLB broth tubes at 35oC + 0.5o for 24 + 2 hr. Examine for gas,formation, and record results.,3.5.6 Incubate gas-negative tubes for an additional 24 + 2 hr, examine, record the number,of additional gas-positive tubes and add to the results obtained in step 3.5.5, above.,3.5.7 Formation of gas during 48 + 2 hr incubation constitutes a positive confirmed test.,3.5.8 Compute the "MPN" of confirmed Coliforms p……
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