摘要:

The following article is an edited version of the presentation given by Dr John Gilbert Davis, founder member of the Society, to the Reading Branch of the London, South and Eastern Section at the University of Reading on 12 March 1987.

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02406.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Approximately 95% of available nitrogen can be precipitated from milk on adjustment to pH 4.6 after heating at 90°C × 15 minutes at its natural pH and pH 7.5, while 89% can be precipitated after heating at pH 10.0 at 60°C × 3 minutes. Non‐recovered protein includes some serum albumin, β‐lactoglobulin, α‐lactalbumin and proteose peptones. Protein isolates precipitated from milk heated at pH>7.0 are more soluble in the pH range 6.0–7.0 than those precipitated from milk heated at its natural pH. Whey proteins complex onto the casein micelles after heating milk at its natural pH, while on heating at pH>7.0 whey proteins appear to interact with k‐casein in the serum phase. When N‐ethylmaleimide is present in milk during heating the percentage protein recovered on pH 4.6 precipitation is decreased, confirming that disulphide linkage is involved in complex formation. However, addition of β‐mercaptoethanol to recovered isolates did not result in dissociation of the casein/whey protein complex, suggesting that forces other than disulphide bonding are also involved in mai

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02407.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02408.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02409.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02410.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Over the last 10 years the range of ‘milks’ which dairy companies market has increased enormously. In addition to true low fat milks (ie, skimmed milk and semi‐skimmed milk), various additive ‘milks’ are now available. These include low fat ‘milks’ with the taste of whole milk, ‘milks’ with added vitamins, ‘milks’ enriched with calcium and ‘milks’ low in lactose. There are even high fat ‘milks’, and of course flavoured milks. Many of these products are available fresh (ie, pasteurized) rather than long‐life (ie, UHT). Improved technology and chilled distribution give the fresh products additional shelf‐life. The equipment for making these products is outlined, as well as the quality control requirement. The releva

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02411.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

At present, only two approaches for modifying the composition of bovine milk can be applied in practice: (a) changing to a breed other than the predominant Friesian and (b) dietary manipulation. Although other breeds may produce milk of high fat and protein content, the high yield of the Friesian, allied to the fact that it is an acceptable meat animal, probably ensures its continued dominance. In terms of diet, the content, yield and type of milk fat are easily susceptible to manipulation. However, the specialized diets required for this type of manipulation would probably incur extra costs, and it is not clear if the improved properties of the butter, eg, a butter having better low‐temperature spreadability, could attract a better return in the market. Protein content and yield are fairly insensitive to diet, and the consensus is that protein composition is invariant. Currently, the most sensible strategy for the dairy farmer appears to be to produce milk as cheaply as possible, and to leave it to the technologists to convert the components into a range of attractive, nutritious foodstuff

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02412.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

In the light of experiences gained and observations made in the dairy industry, the critical control points and factors that affect the operation of the DEFT (Direct Epifluorescent Filter Technique) in a routine laboratory were determined. Recommendations are made for the optimization of both the test protocol and the instrumentation, and the need for adequate operator training is strongly emphasized.

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02413.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02414.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

ISSN:1364-727X    

DOI:10.1111/j.1471-0307.1987.tb02417.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY