摘要:

SUMMARYThirty broiler chickens of known weight and history were processed simultaneously under normal conditions in each of three poultry packing stations, visually assessed to be operating at ‘ideal’, ‘good’, and ‘poor’levels of hygiene. The eviscerated carcases were bisected, cooled to 3° in chilled air, and distributed between three treatment groups which were dipped for 30 min in chilled water containing 0, 10 and 20 p/m of chlortetracycline respectively. During storage at 3° for 3 weeks, microbiological and sensory examinations were undertaken. At all levels of hygiene, the application of the antibiotic significantly delayed the onset of spoilage; the differences between the effects of 10 and 20 p/m were small and generally insignificant. Bacterial counts of 106/cm2of skin were obtained from the controls on the 7th day of storage whereas similar counts on the treated groups were not reached until the 14th day. ‘Off’odours developed in the control groups between the 5th and 7th days and in the treated groups between the 10th and 14th days. The nature of the spoilage flora acquired during processing appeared to be associated with the du

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00190.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYTwenty broiler chickens of known history were processed, bisected, randomly distributed between two groups and then cooled for 2 hr in water and ice. One group was treated with 10 p/m of chlortetracycline. After wrapping, the carcases were blast frozen and stored, first at —15° for 5 months, and then at 3°. During the latter period sensory examinations were done. Treatment with chlortetracycline delayed the appearance of visible microbial growth from a mean of 6·2 days in the controls to 7·8 days, and the onset of ‘off’ odours was also delayed, from a mean of 6·1 days in the controls to 8·5 days. It appeared that poultry meat which had been frozen and thawed was more highly perishable than fresh chilled p

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00191.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYA laboratory process for the microbial production of sulphide from sewage sludge enriched with sulphate has been further developed. Semicontinuous fermentations yielded 0·9–1·0% S2‐using a 10‐day replacement time (RT) and 0·8% S2‐with a 5‐day RT. Yields at 37° were slightly higher than at 30°; at 43° and above yields were much lower. A mixture of 70% N2and 30% CO2was successfully used as sweeping gas to remove H2S; other proportions of these gases were less efficient. Stripping H2S from the sludge in an external column was as efficient as passing the stripping gas through the bulk of the fe

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00192.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYThe coli‐aerogenes organisms content, determined by plating on violet red‐bile agar, of surface soil from a polluted site (heavily grazed pasture) often exceeded 104/g at 30° and 103/g at 37°.Escherichia coliI was present but in a small proportion only. High coli‐aerogenes counts were much less frequent in unpolluted soil (enclosed Forestry Plantation), andE. coliI was relatively rare. The classification of 1,917 strains isolated from colonies on VRB agar at 30° and at 37° showed thatKlebsiella cloacaewas very much the dominant species in both sites when the plates were incubated at 30°, whereasCitrobacter freundiiI andK. cloacaewere co‐dominant when incubation was at 37°.E. coliII constituted a relatively high proportion of the strains from both sites but, due to the very marked dominance of these three types,E. coliI was rarely isolated by the method employed, even from the polluted soil. The very high incidence of non‐lactose‐fermenters, particularly among the dominant types, was the outstanding characteristic of the strains isolated, even with incubation at 37°. Only 29% formed acid and gas in MacConkey's broth within 2 days at 37°, while 59% formed acid and gas within 5 days at 30° but failed to do so in 2 days at 37°. There was a much higher incidence of coli‐aerogenes organisms in soil from the unpolluted site during summer than during winter, and this is attributed to possible multiplication of 37° negative strains

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00193.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYEnterobacteriaceae which can grow at the temperatures prevailing in refrigerated food stores (‘psychrotrophic’Enterobacteriaceae) can be distinguished from strains which cannot develop below 10° because the latter generally grow quickly on nutrient agar at 43°0±1° whereas the former do not. By this test inadequately refrigerated foods can be differentiated from those kept properly refri

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00194.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYA case is presented for the introduction of the term ‘psychrotrophic’ for bacteria able to grow at 5° or less. The term ‘psychrophilic’ should be used only when a low optimum temperature is

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00195.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYDuring the period April‐December 1959 some 7,834 samples of pasteurized milk were examined. From the positive presumptive results in MacConkey's broth at 37°, 165 cultures were obtained which fermented lactose at 44°. From 1957 to 1959, 11,400 washed bottles were tested and 694 gave a positive result in MacConkey's broth at 30°; only 12 of these cultures were positive at 44°. None of the strains ofE. coliwas a pathogenic ser

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00196.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYStreptococci, lactobacilli and coli‐aerogenes organisms were isolated from pigs receiving penicillin, chlortetracycline or copper sulphate as dietary supplements. Changes in their numbers, physiological type and sensitivity to the supplements fed are described. Penicillin and chlortetracycline rapidly induced a population resistant to the antibiotic fed, but no changes were detected in numbers or types of organisms isolated. Copper sulphate caused a reduction in the numbers of streptococci and a change of predominant type from non‐lactose‐fermenting to lactose‐fermenting; there was also a change from a flora in whichL. acidophiluspredominated to one in whichL. brevisandL. cellobiosustended to become d

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00197.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

摘要:

SUMMARYMatured Wiltshire bacon normally carries 105–106viable bacteria/g when sliced, predominantly salt tolerant micrococci and lactobacilli.Kept at 15°, the numbers rose in 4 days to 107–108/g, the flora remaining generally similar in nature and with higher counts at 20° than at 37°. The situation then stabilized; there was a slow decline in organoleptic quality, but nothing unusual occurred in two weeks. Kept at 37°, similar numbers were reached after 1 day, and the nature of the flora changed rapidly, counts at 37° much exceeding those at 20°. Organoleptic deterioration was marked after 2 days and the bacon was unacceptable after 4 days. These changes occurred whether the bacon was packed in air or in 5% oxygen, the oxygen being all consumed in 4 days or less according to temperature. Apparently, if the bacon is kept at too high a temperature for its normal psychrophilic (20° optimum) flora, this is replaced by a mesophilic (37° optimum) flora. It appears that pathogenic staphylococci might be present in this mesophilic flora. A high proportion of isolates proved to be phosphatase positive, or 44° positive; and some had both these properties. Though all, so far, have been coagulase negative, there is no evident reason why pathogenic types shou

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00198.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY

ISSN:0021-8847    

DOI:10.1111/j.1365-2672.1960.tb00199.x

出版商:Blackwell Publishing Ltd    

年代:1960

数据来源: WILEY