Destabilization of ultra-instantaneous UHT sterilization milk stored at different temperatures

Ke Fan; Peipei Wu; Mengyuan Guo; Yi Wang; Ye Cao; Pengjie Wang; Fazheng Renb; Jie Luo

doi:10.3168/jds.2024-24705

Destabilization of ultra-instantaneous UHT sterilization milk stored at different temperatures

J Dairy Sci. 2024 Mar 28:S0022-0302(24)00635-0. doi: 10.3168/jds.2024-24705. Online ahead of print.

Authors

Ke Fan¹, Peipei Wu¹, Mengyuan Guo², Yi Wang², Ye Cao¹, Pengjie Wang², Fazheng Renb³, Jie Luo⁴

Affiliations

¹ College of Food Science and Technology, Hunan Agricultural University, Changsha, 410114, China.
² Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
³ College of Food Science and Technology, Hunan Agricultural University, Changsha, 410114, China; Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address: renfazheng@cau.edu.cn.
⁴ College of Food Science and Technology, Hunan Agricultural University, Changsha, 410114, China; Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address: luojie@hunau.edu.cn.

PMID: 38554824
DOI: 10.3168/jds.2024-24705

Abstract

Ultra-instantaneous UHT (UI-UHT, > 155°C, < 0.1 s) treated milk exhibits higher retention of active protein than regular UHT milk. However, UI-UHT products demonstrate increased susceptibility to destabilization during storage. This study aimed at monitoring the destabilizing process of UI-UHT milk across different storage temperatures and uncovering its potential mechanisms. Compared with regular UHT treatment, ultra-instantaneous treatment markedly accelerated the milk's destabilization process. Aged gel formation occurred after 45 d of storage at 25°C, while creaming and sedimentation were observed after 15 d at 37°C. To elucidate the instability mechanism, measurements of plasmin activity, protein hydrolysis levels, and proteomics of the aged gel were conducted. In UI-UHT milk, plasmin activity, and protein hydrolysis levels significantly increased during storage. Excessive protein hydrolysis at 37°C resulted in sedimentation, while moderate hydrolysis and an increase in protein particle size at 25°C resulted in aged gel formation. Proteomics analysis results indicated that the aged gel from UI-UHT milk contained intact caseins, major whey proteins, and their derived peptides. Furthermore, specific whey proteins including albumin, lactotransferrin, enterotoxin-binding glycoprotein PP20K, and MFGM proteins were identified in the gel. Additionally, MFGM proteins in UI-UHT milk experienced considerable hydrolysis during storage, contributing to fat instability. This study lays a theoretical foundation for optimizing UI-UHT milk storage conditions to enhance the quality of liquid milk products.

Keywords: Age gelation; Creaming; Proteomics; UI-UHT milk.

© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).