title: Analysis of water sorption isotherms of amorphous food materials by solution thermodynamics with relevance to glass transition: evaluation of plasticizing effect of water by the thermodynamic parameters.
abstract: Relation between the thermodynamic parameters obtained from water sorption isotherms and the degree of reduction in the glass transition temperature (Tg), accompanied by water sorption, was quantitatively studied. Two well-known glassy food materials namely, wheat gluten and maltodextrin were used as samples. The difference between the chemical potential of water in a solution and that of pure water ([Formula: see text]), the difference between the chemical potential of solid in a solution and that of a pure solid ([Formula: see text]), and the change in the integral Gibbs free energy ([Formula: see text]) were obtained by analyzing the water sorption isotherms using solution thermodynamics. The parameter [Formula: see text] correlated well with ΔTg(≡Tg- Tg0; where Tg0is the glass transition temperature of dry material), which had been taken to be an index of plasticizing effect. This indicates that plasticizing effect of water on foods can be evaluated through the parameter [Formula: see text].
authors.affiliation: a Faculty of Home Economics, Department of Food Science and Nutrition , Kyoritsu Women's University , Tokyo , Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Shimazaki
authors.affiliation: a Faculty of Home Economics, Department of Food Science and Nutrition , Kyoritsu Women's University , Tokyo , Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tashiro
authors.affiliation: b Department of Chemistry and Life Science , College of Bioresource Sciences, Nihon University , Kanagawa , Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Kumagai
authors.affiliation: a Faculty of Home Economics, Department of Food Science and Nutrition , Kyoritsu Women's University , Tokyo , Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kumagai
mesh_terms: D005504:Food Analysis; D005898:Glass / Q000737:chemistry; D005983:Glutens / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D044366:Transition Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D010968:Plasticizers; D011134:Polysaccharides; D012996:Solutions; D014867:Water; C008315:maltodextrin; D005983:Glutens
keywords: glass transition; gluten; plasticizer; thermodynamics; water sorption