title: Effect of moisture content on selected physicochemical properties of two commercial hen egg white powders.
abstract: After short-term storage at 23°C, selected physicochemical properties of two hen egg white powders (with and without hydrolysis) were studied. Overall, the effect of moisture content on physicochemical properties of Hydrolysed Egg White powder (HEW) was more severe than those of Dried Egg White powder (DEW). The denaturation temperature (Td) and its enthalpy change (ΔHd) of ovalbumin in DEW followed an exponential model, as well as the Td of HEW. The Gordon-Taylor equation modelled well the glass transition temperatures (Tg) of HEW and DEW. The Guggenheim-Anderson-de Boer (GAB) model fitted well to the type II moisture sorption isotherm. At the critical moisture content (12.0%, dry basis), compared with DEW, the colour of HEW began to darken dramatically and its hardness started to change significantly. These changes were closely related to the inherent characteristics of the two products. The mechanisms relevant to these physicochemical changes were discussed.
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave., St. Paul, MN 55108, United States.
authors.forename: Qinchun
authors.initials: Q
authors.lastname: Rao
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Ave., St. Paul, MN 55108, United States. Electronic address: tplabuza@umn.edu.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Labuza
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002645:Chickens; D004529:Egg White / Q000737:chemistry*; D005260:Female; D011208:Powders / Q000737:chemistry*; D011489:Protein Denaturation
chemical_list: D011208:Powders
keywords: Egg white powder; Glass transition; Moisture content; Physicochemical properties; Protein denaturation; Water activity