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http://krishi.icar.gov.in/jspui/handle/123456789/60787
Title: | Assessment of physico-chemical changes in UHT milk during storage at different temperatures. |
Other Titles: | Not Available |
Authors: | Suvartan, R.; Sharma, R.; Gandhi, K. and Mann, B. |
ICAR Data Use Licennce: | http://krishi.icar.gov.in/PDF/ICAR_Data_Use_Licence.pdf |
Author's Affiliated institute: | ICAR::National Dairy Research Institute |
Published/ Complete Date: | 2020-04-21 |
Project Code: | Not Available |
Keywords: | NCN; NPN; particle size; UHT milk; zeta potential |
Publisher: | Not Available |
Citation: | Not Available |
Series/Report no.: | Not Available; |
Abstract/Description: | Ultra high temperature (UHT) processing is carried out at very high temperature for short periods of time (135–150°C for 1–10 s), resulting in production of sterile milk which when packaged aseptically is stable for about 6 months at room temperature. During storage of UHT milk, various physio-chemical changes and enzymatic reactions take place including dephosphorylation of casein micelles, breakdown of lactose, precipitation of calcium phos phate, disturbance of salt balance and proteolysis (Gaucher et al., 2008; Aldubhany et al., 2014). These changes drastically affect the quality of UHT milk as a result of gelation, which limits its shelf life and thus the consumer acceptance (Rauh et al., 2014). Age-gelation is a major problem in UHT milk which is related to proteolysis by action of native plasmin or psychotropic bacterial protease (Chavan et al., 2011). Many reasons have been proposed to explain age-gelation such as acidification, Maillard reaction, enzymatic and physico-chemical proteolysis (Gaucher et al., 2008; Chavan et al., 2011; Rauh et al., 2014). The gelation of the product occurs in a two-stage mechanism. In the first stage, casein micelles get dissociated from the complex formed between denatured β-lactoglobulin and k-casein during heating of UHT milk. Second stage involves exclusively the physico-chemical changes, which finally results in aggregation of casein micelles forming a 3D structure, causing gelation (Gaucher et al., 2008; Chavan et al., 2011). However, Auldist et al. (1996) failed to show any correlation between rate and extent of proteolysis with the onset of age-gelation, sup porting the importance of the second stage gelation mechanism. The exact mechanism of gel ation during storage of UHT milk is not yet clear and is still debatable. The objective of the present study was to throw light on the mechanism of first stage reaction of proteolysis, the aggregation of casein micelles and formation of a 3D structure. We investigated the suscepti bility of UHT milk to proteolysis during storage. Changes in size and zeta potential of casein micelles, salt balance and nitrogenous compounds were also assessed which were correlated with proteolysis in UHT processed milk during storage at room as well as refrigerated temperature. |
Description: | Not Available |
ISSN: | Not Available |
Type(s) of content: | Research Paper |
Sponsors: | Not Available |
Language: | English |
Name of Journal: | Journal of Dairy Research |
NAAS Rating: | 7.63 |
Volume No.: | 87 |
Page Number: | 243–247 |
Name of the Division/Regional Station: | Not Available |
Source, DOI or any other URL: | 10.1017/S0022029920000266 |
URI: | http://krishi.icar.gov.in/jspui/handle/123456789/60787 |
Appears in Collections: | AS-NDRI-Publication |
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