ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03872.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.It has been shown that the effect of heating rinses of Ringer solution alone varies with their source, and a t the temperature tested the addition of protective colloids, like milk, is ineffective only with a minority of rinses. It is suggested that in order to obtain a more correct estimation of the number and types of heat‐resistant organisms present in rinses of equipment, sterile skim miIk should be added prior to heat treatment in the proportion of 9 parts skim milk to 1 part Ringer solutio

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03873.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.The history of the thermoduric problem in milk in the Belfast area has been given and an explanation of the cause offered.It has been shown that in Northern Ireland failure to cool the milk does not lead to any marked increase in the number of thermoduric bacteria. Provided there is no definite source of contamination, the build‐up of thermoduric organisms on farm equipment is slow even where production methods are poor and where suitable washing and sterilising of equipment is absent. Even under these conditions a serious build‐up takes longer than a mo

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03874.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.Development of hydrogen sulphidc in sewage, due to growth of sulphate‐reducing bacteria, is favoured by neutral or alkaline conditions and retarded by acidic conditions. Strains able to use lactate, formate, stearate, and cellulose as sources of carbon were detected by the use of appropriate media; no sulphate‐reducing bacteria capable of using tributyrin appeared to be present in the sample of sewage tested.Doses of chlorine much smaller than the chlorine demand delayed the formation of sulphide, sometimes for several days, but eventually the quantity formed was of the same order as that in untreated sewage.Addition to sewage of nitrobenzene, dinitrobenzene, picric acid, or T.N.T., in amounts ranging from 2 to 20 p.p.m. in different tests, delayed development of sulphide during subsequent incubation; sufficiently high concentrations prevented its formation for prolonged periods.Fumarate and nitrate also tended to inhibit formation of sulphide, but the concentrations required (100‐1,000 p.p.m. for nitrate and 1,000–10,000 p.p.m. for fumarate) were much higher than for the above nitro‐compounds.Neither T.N.T. nor picric acid had any marked bactericidal action. It is suggested that these nitro‐compounds retard the lowering of the oxidation‐reduction potential uf the sewage to the region favourable for development of the sulphate‐red

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03875.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03876.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.A series of experiments was carried out to ascertain which test or combination of tesrs in common use would provide the best indication of thc keeping quality, methods of production, and adequacy of cooling of milk.Monthly tests were made of milk as produced by two groups of farms (“good” and “poor”) in two widely separated areas. The good farms practised twice daily. sterilisation and efficient cooling; thc poor farms practised neither.The tests examined were: (1) colony count (4 days at 30°C.) on fresh (4 hr.) and aged (22 hr. at 18°C.) raw milk, and (in laboratory pasteurized fresh and aged milk; (b) clot‐on‐boiling (storage a t 18°C.); (c) resazurin to complete reduction at 37°C. on fresh raw and aged raw milk: (d) methylene blue reduction time at 18°C. on laboratory pasteurized fresh and aged milk; (e) methylene blue reduction time at 37°C. on laboratory pasteurized fresh and aged milk.No single test gave complete differentiation between good and poor production mcthods; the colony count of laboratory pasteurized aged milk was the nearest approach. In general the thermoduric colony count increased very little in raw milk aged at 18°C. for 24 hr.: the inean increases after ageing mere only 8.4% and 10.O% in the two areas.In all, 36 combinations of tests were considered, althouglh it has not been possible to present in either graphical or tabular form those combinations which showed promise; this is done for what is considered the most suitable combination‐the tiiermoduric count of aged milk and the clot‐on‐boiling time.Visual evidence of poor production methods was frequently associated with poor keeping quality, but lack of evidence of poor production gave no guarantee of good keeping quality. The keeping quality test alone was not entirely reliable as an ind

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03877.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03878.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03879.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03880.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Summary.To determine whether a time‐temperature compensation scale can be applied to the methylene blue test samples of fresh raw milk from nearby farms and local creameries were examined at regular intervals throughout a twelve‐month period. Each sample was divided into seven sub‐samples which were stored for approximately 24 hr. in water baths controlled at 37.5°, 42.5°, 47.5°, 52.5°, 57.5°, 62.5° and 67.5° F.; decolourisation of methylene blue at 37°C. was observed at regular intervals.Average times of reduction of methylene blue following storage at different temperatures are given saparetely for the various keeping quality groups (time to endpoint with clot‐on‐boiling at 15.5°C.). The mean times for samples of all keeping quality groups to reduce methylene blue at all pre‐test storage temperatures are found to li

ISSN:0370-1778    

DOI:10.1111/j.1365-2672.1949.tb03881.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY