ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02283.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02284.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02285.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02286.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02287.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02288.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02289.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

SummaryThe investigation had as its principal objects, determination of the microbiological effectiveness of the chlorination of polluted water supplies used for buttermaking, the influence of high chlorine dosages on butter flavour and an examination of the reproducibility of butter grading by subjective methods.A preliminary trial in which pasteurized sweet cream was made into butter using polluted as well as chlorinated water, revealed that there were marked differences in the condition and quality of the finished product. Butter washed with contaminated water developed rancidity within twenty‐one days at 37 to 41 °F. whereas water from the same source, but which contained 5 p. p.m. residual chlorine, resulted in butter which retained a pleasing flavour and aroma for six weeks.In the main experiment, six duplicate lots of unsalted butter were made from ripened cream, using treated and untreated water from the same source, with identical buttermaking methods. The untreated water contained large numbers of psychrophilic bacteria, includingPseudomonas putrefaciens. These organisms grew actively in unsalted butter held at 45 to 50°F. Chlorination of the water with varying dosages of from 10 to 200 p. p.m. available chlorine, sixteen hours before use, resulted in practically a complete destruction of the spoilage organisms. The cream used during the main experiment was ripened at 40 to 50°F. for two days after pasteurizing by the H. T.S. T. method before churning. On microbiological examination, the butter produced from this cream was found to contain large numbers of spoilage organisms, and became rancid within four weeks when stored at 45 to 50°F. However, the microbiological results indicate the superior quality of those butters made with chlorinated water.A consensus of the grading results obtained, substantiates the anticipated superior quality of butter made using chlorinated water, compared with that made with an impure supply. No chlorine taint was detected in the butter, although water containing as much as 100 to 200 p. p.m. residual chlorine had been used in preparing two of the samples. The arbitrary nature of subjective grading is reflected in the differing conclusions arrived at by individual members of the graders'

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02290.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02291.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY

摘要:

Summary(1) During the six months preceding the start of the Angus scheme 118 milk samples from the thirteen farms concerned were examined when approximately thirty hours old. Twenty‐six per cent of these samples were coliform positive in 1/100 ml. and 7 per cent had 37°C. colony counts exceeding 200,000/ ml.(2) Of 230 milk samples from the farm tanks examined within ten hours of sampling 9.6 per cent were coliform‐positive in 1/100 ml. and 1.3 per cent had 37°C. colony counts exceeding 200,000/ml. Eighty‐seven per cent of the samples had counts below 10,000/ml.(3) Surface plate counts at 27°C. showed much higher counts and greater variation than the 37°C. counts. Bacterial counts at both 27°C. and 4°C. frequently showed big increases after storage of the samples for eighteen hours at 4°C.(4) Forty‐nine milk samples were taken from the road tanker. Twenty per cent of these were coliformpositive in 1/100 ml. but the greatest count obtained was only 54,000/ml.(5) Of 163 swabs arid rinses from fourteen farm tanks 10 per cent were coliform‐positive in 1 ml. and over 46 per cent had 37°C. counts greater than 100/swab. Surface plate counts at 27°C. frequently exceeded 100,000/swab. Rubber‐seated thermometers generally gave unsatisfactory swabs.A detergent‐hypochlorite cleansing routine gave fewer coliform‐positive swabs and lower counts th

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1958.tb02292.x

出版商:Blackwell Publishing Ltd    

年代:1958

数据来源: WILEY