Significance of frictional heating for effects of high pressure homogenisation on milk

Datta, N, Hayes, MG, Deeth, HC and Kelly, AL (2005) Significance of frictional heating for effects of high pressure homogenisation on milk. Journal of Dairy Research, 72 4: 393-399. doi:10.1017/S0022029905001056

Author Datta, N
Hayes, MG
Deeth, HC
Kelly, AL
Title Significance of frictional heating for effects of high pressure homogenisation on milk
Journal name Journal of Dairy Research   Check publisher's open access policy
ISSN 0022-0299
Publication date 2005-01-01
Sub-type Article (original research)
DOI 10.1017/S0022029905001056
Open Access Status Not yet assessed
Volume 72
Issue 4
Start page 393
End page 399
Total pages 7
Place of publication UK
Publisher Cambridge
Language eng
Subject C1
290103 Food Processing
670105 Dairy products
Abstract High pressure homogenisation (HPH) is a novel dairy processing tool, which has many effects on enzymes, microbes, fat globules and proteins in milk. The effects of HPH on milk are due to a combination of shear forces and frictional heating of the milk during processing; the relative importance of these different factors is unclear, and was the focus of this study. The effect of milk inlet temperature (in the range 10-50 degrees C) on residual plasmin, alkaline phosphatase, lactoperoxidase and lipase activities in raw whole bovine milk homogenised at 200 MPa was investigated. HPH caused significant heating of the milk; outlet temperature increased in a linear fashion (0(.)5887 degrees C/degrees C, R-2 =0-9994) with increasing inlet temperature. As milk was held for 20 s at the final temperature before cooling, samples of the same milk were heated isothermally in glass capillary tubes for the same time/temperature combinations. Inactivation profiles of alkaline phosphatase in milk were similar for isothermal heating or HPH, indicating that loss of enzyme activity was due to heating alone. Loss of plasmin and lactoperoxidase activity in HPH milk, however, was greater than that in heated milk. Large differences in residual lipase activities in milks subjected to heating or HPH were observed due to the significant increase in lipase activity in homogenised milk. Denaturation of beta-lactoglobulin was more extensive following HPH than the equivalent heat treatment. Inactivation of plasmin was correlated with increasing fat/serum interfacial area but was not correlated with denaturation of beta-lactoglobulin. Thus, while some effects of HPH on milk are due to thermal effects alone, many are induced by the combination of forces and heating to which the milk is exposed during HPH.
Keyword Agriculture, Dairy & Animal Science
Food Science & Technology
High Pressure Homogenisation
Milk Enzymes
Alkaline Phosphatase
Fat Globule Size
Whey Proteins
Q-Index Code C1

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Created: Wed, 15 Aug 2007, 16:53:45 EST