Influence of Heat- and Cold-Stressed Raw Milk on the Stability of UHT Milk

This study investigated the variations and alterations in the concentrations of plasmin system components in raw and UHT (ultra-high-temperature) milk under cold stress (WCT ≤ −25 °C), heat stress (THI ≥ 80), and normal (THI < 70 and WCT ≥ −10 °C) circumstances. The findings indicated elevated am...

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Bibliographic Details
Main Authors: Nan Li, Zhigang Yang, Zhiyu Yuan, Zizhu Zhen, Xinna Xie, Danqing Zhu, Gang Lu, Feng Zhao, Bo Qu, Bingli Qi, Yujun Jiang, Qianyu Zhao, Chaoxin Man
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Foods
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Online Access:https://www.mdpi.com/2304-8158/14/1/3
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Summary:This study investigated the variations and alterations in the concentrations of plasmin system components in raw and UHT (ultra-high-temperature) milk under cold stress (WCT ≤ −25 °C), heat stress (THI ≥ 80), and normal (THI < 70 and WCT ≥ −10 °C) circumstances. The findings indicated elevated amounts of plasmin system components in cold-stressed raw milk. While storing UHT milk at 25 °C, the concentrations and activity of plasmin in the milk exhibited an initial increase followed by a decrease, peaking around the 30th day. The maximum plasmin level and activity in cold-stressed milk were 607.86 μg/L and 15.99 U/L, respectively, with the beginning of gelation occurring around day 60. The higher activity of plasmin in cold-stressed milk led to the poorer stability and sensory assessment of the milk. However, heat-stressed milk is not such a problem for UHT milk as cold-stressed milk. The findings indicate shortcomings in the quality of cold-stressed milk and its adverse effects on the stability of UHT milk, underscoring the necessity of preventing cold stress in the herd and refraining from utilizing cold-stressed milk as a raw material for UHT production.
ISSN:2304-8158