The Effect of Pasteurization on Esch. Coli in Milk and Ice Cream Mix

Paley, Charles; Isaacs, M. L.

doi:10.3168/jds.s0022-0302(41)95427-9

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…survived similar treatment in ice-cream mix, but later Nelson Caulfield & Martin (41) reported that these types were destroyed more readily than phosphatase. Paley & Isaacs (25) found that the heat resistance (at 143° F.) of coli in ice-cream mix was double that in milk, and attributed the difference to a protective action of stabilizer gums. In Britain, however, such considerations are less important, since ice-cream mixes are usually processed at temperatures higher than 145° F.…”

Section: Coliform Strainsmentioning

confidence: 99%

333. The coliform flora of milk and dairy products

Crossley

1946

Journal of Dairy Research

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233mastitis the four quarters were cited as A, B, C and D as follows: A, left front; B, right front; C, left hind; D, right hind. The simplest way to ensure that the claw was correctly applied was found to be the use of a standard position for the bucket relative to the direction in which the cow was facing. The bucket was always placed with the arrow on the lid pointed to the head of the bail, and care was taken that there was no twist in the long connecting tubes to the claw. The claw was applied to the teats with the straight tubes along instead of across the bail. With this system there was no need to alter the position of the bucket for right-and left-hand bails. It was found that there was little difficulty in using the claw as described instead of in the more usual position, transverse to the bail. Milking proceeded normally as for an ordinary bucket plant. The strip bucket was used in the same way with the arrow towards the head of the bail, so giving automatically an adjustment for right-and left-hand bails. On completion of stripping, the two buckets were placed side by side with the arrows pointing in the same direction, and the strippings were added to the corresponding quadrant container in the milking-machine bucket before weighing and sampling.The coliform organisms have probably received more attention than most other groups of non-pathogenic bacteria owing to their importance as ' indicator' species in water analysis, wherein two distinct procedures have long been employed, viz. (a) a presumptive test to demonstrate the presence or absence of coliform species in general, performed by inoculation into bile salt-lactose broth (Britain) or lactose broth (America), and (b) confirmatory tests designed to isolate and differentiate faecal from non-faecal types.Subsequently the 'coliform test' has been widely adopted in Britain for the examination of raw-milk supplies, and quantitative standards have been introduced for grading special designated raw milks. Similar tests are used extensively in pasteurized milk control, although no legal standard has been adopted. In order to facilitate examination of large numbers of samples, only the presumptive test is performed in dairy work. The validity of this procedure has been questioned by numerous workers, particularly in America, on the ground that interpretation of the test must be uncertain since faecal types are not differentiated. Conversely, it is argued that the presumptive test is sufficient since undesirable changes in milk or milk products may be produced equally by faecal and

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Section: Coliform Strainsmentioning

confidence: 99%

333. The coliform flora of milk and dairy products

Crossley

1946

Journal of Dairy Research

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Section B. Bacteriology and mycology applied to dairying

Hiscox¹,

Rowlands²

1947

Journal of Dairy Research

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Reviews of the progress of dairy science 637.0:576.8 SECTION B. BACTERIOLOGY AND MYCOLOGY APPLIED TO DAIRYING PAGE Thom6 (39) has studied the change in flora during the incubation of samples in the methyleneblue test. The proportion of the different types, which consisted mainly of streptococci, micrococci and coliform organisms, changed during incubation. Initially the flora of different samples consisted of 7-100% streptococci, 0-95% micrococci and 0-6% coliform organisms; at the time of reduction the proportions were respectively 20-88, 9 r 65 and 0-24%. The reducing ability of pure cultures of representatives of the three groups, in terms of the time taken for an inoculum of 1 million organisms per ml. to reduce methylene blue in 'sterile' milk, was approximately the same, though at the time of reduction counts were higher for streptococci and coliform organisms than for micrococci. With mixed cultures, the rates of increase of each type were changed with varying proportions of inoculum, although the time for complete reduction was not materially affected. Morris (40) has observed that proliferation of psychrophilic bacteria of the genus Pseudomonas, derived from the water supplies used on the producing farms, may lead to a shortening of the reduction time after overnight storage of milk samples in a refrigerator. Reviews of the progress of dairy scienceMany papers dealing with different aspects of the resazurin test have appeared during the period under review. Resazurin has been synthesized (4J) and standards have been suggested for preparations intended for milk testing; these standards have been adopted for resazurin used for official milk tests in this country (42). According to Johns (43) resazurin tablets approved for use in North America are approximately 60% stronger than those used in this country. The use of the stronger solution made colour differentiation easier, especially when dealing with cream, colostrum, and milks tending to give a grey tinge when mixed with the dye, but it delayed by about 30 mm, the time taken to reach the pink stage, although there was no difference in the time taken to reach the Munsell P7/4 colour standard (about half-way between the initial blue and the full pink stage). Thomas(44), however, found that doubling the concentration of resazurin only slightly delayed the time taken to reach Lovibond disk 4, 2 or 0.The interpretation of results obtained by workers in different countries is complicated by the use of different colour standards for the intermediate stages of reduction. Golding & Jorgensen (45) have compared the colour standards of a Munsell colour grader with those of the Lovibond disk; the average disk values were 6 for Munsell A, 4-95 for B, 3-85 for C and 2-35 for D. In some European countries a colour chart (Dr Kloz) graduated in four classes is used(ll): class I corresponds to the initial colour (blue) of resazurin in milk, class IV to the mixture of resorufin and milk (pink), and classes II and III represent the transitions between these two extremes. A...

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The Effect of Pasteurization on Esch. Coli in Milk and Ice Cream Mix

Cited by 2 publications

References 3 publications

333. The coliform flora of milk and dairy products

333. The coliform flora of milk and dairy products

Section B. Bacteriology and mycology applied to dairying

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