title: Stability of whey protein hydrolysate powders: effects of relative humidity and temperature.
abstract: Whey protein hydrolysate (WPH) is now considered as an important and special dairy protein ingredient for its nutritional and functional properties. The objectives of the present study were to investigate the effect of environmental relative humidity (RH) and storage temperature on the physicochemical stability of three WPH powders with hydrolysis degrees (DH) of 5.2%, 8.8% and 14.9%, respectively. The water sorption isotherms of the three WPH powders fitted the Guggenheim-Andersson-DeBoer model well. An increase in water content leaded to a decrease in glass transition temperature (Tg), following a linear Tg vs log water content relationship. Moreover, an increase in DH caused the decrease in Tg at the same water content. Changes in microstructure and colour occurred significantly when the WPH powders were stored at high environmental RH or temperature, especially for those with high DH.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China; Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN 55108, USA. Electronic address: zhoupeng@jiangnan.edu.cn.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China.
authors.forename: Dasong
authors.initials: D
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China.
authors.forename: Yingjia
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, Saint Paul, MN 55108, USA.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Labuza
mesh_terms: D006813:Humidity; D006868:Hydrolysis; D008894:Milk Proteins / Q000737:chemistry*; D011208:Powders / Q000737:chemistry; D011492:Protein Hydrolysates / Q000737:chemistry*; D055550:Protein Stability; D044366:Transition Temperature; D014867:Water / Q000032:analysis; D000067816:Whey Proteins
chemical_list: D008894:Milk Proteins; D011208:Powders; D011492:Protein Hydrolysates; D000067816:Whey Proteins; D014867:Water
keywords: Colour; Glass transition; Microstructure; Powder; Water content; Whey protein hydrolysate