ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02157.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02158.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Recent reports in the literature indicate that incidents involving fires and explosions in the spray drying of milk products are increasing in number. While milk powder is not highly explosible, the conditions for a dust explosion, apart from the ignition source, are almost always present in certain areas of a spray drying system during its normal operation. Self‐ignition of deposits is known to be possible at the high temperatures in a spray drier. At best, this can cause product degradation and discoloration and at worst it can provide the source of ignition for an explosion. This paper is an attempt to draw together recent work on fire and explosion prevention and protection for milk powder

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02159.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The article describes a non‐intrusive technique that is used to investigate the sedimentation/creaming of particles in a dispersion dire to gravity. The velocity of ultrasound is measured over a series of heights in the dispersion, and the data are converted to concentration profiles which are collected over a period of time. Often the method detects sedimentation/creaming at a very early stage and can therefore predict the long‐term shelf‐life of a product. The concentration profiles reveal information on the mechanisms of separation, and in certain cases give the particle size distribution and properties of the sediment/cream layer. The application of the technique to dairy products is disc

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02160.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02161.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Whole and skimmed milks were subjected to a range of high temperature short time treatments using a pilot scale plate heat exchanger. γ‐Glutamyl transpeptidase activity was assayed in the milks and the residual activities compared against the holding temperatures and total heat treatment. There was no residual activity following treatments of 78°C for 15 seconds, a total heat treatment 8.2 times more severe than that of a hold of 15 seconds at 72

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02162.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The detection of phosphatase activity is used as a legal test to determine whether milk has been adequately pasteurized or whether it has been contaminated with raw milk. Occasional failures of the Milk Regulations phosphatase test were experienced by a processing dairy from stored silo milk. Trials demonstrated that the phosphatase was heat resistant and associated with a pasteurization‐sensitive, psychrotrophic organism isolated from one supply. The standard total viable count at 30°C (TVC) of the supply was satisfactory at 4.59 log cfu/ml; however, the psychrotrophic count at 7°C was much higher at 5.61 log cfu/ml. The test milk after storage produced sufficient heat‐resistant phosphatase activity to give a test failure when the psychrotrophic count reached about 7.09 log cfu/ml or greater. The occurrence of a failure was dependent on the initial numbers of psychrotophic bacteria, the amount of dilution with other milks and the storage time before processing. The psychrotrophic count of the test milk and the count of the phosphatase‐producing isolate were found to increase by approximately one log cfu/ml each day on storage at 4°C. This investigation has shown that a phosphatase failure may indicate the development of microbial phosphatase rather than a process failure. A retest after laboratory pasteurization of any sample failing the test will assist in identifying any microbially produced heat‐resistant phosphatase activity. While a TVC at 30°C will normally be expected to count most types of psychrotrophic organisms, this investigation has shown that on this occasion it did not detect specific psvchrotophic organisms which had contaminat

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02163.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02164.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02165.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1989.tb02167.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY