title: Protein Aggregates May Differ in Water Entrapment but Are Comparable in Water Confinement.
abstract: Aggregate size and density are related to gel morphology. In the context of the water distribution in complex food systems, in this study, it was aimed to investigate whether protein aggregates varying in size and density differ in entrapped and confined water. Heat-set soy protein aggregates (1%, v/v) prepared in the presence of 3.5 mM divalent salts increased in size and decreased in apparent density following the salt type order MgSO4, MgCl2, CaSO4, and CaCl2. In the absence of applied (centrifugal) forces, larger and less dense aggregates entrap more water. When force is applied from larger and more deformable aggregates, more water can be displaced. Entrapped water of ∼8-13 g of water/g of protein is associated with (pelleted) aggregates, of which approximately 4.5-8.5 g of water/g of protein is not constrained in exchangeability with the solvent. The amount of confined water within aggregates was found to be independent of the aggregate density and accounted for ∼3.5 g of water/g of protein. Confined water in aggregates is hindered in its diffusion because of physical structure constraints and, therefore, not directly exchangeable with the solvent. These insights in the protein aggregate size and deformability in relation to water entrapment and confinement could be used to tune water holding on larger length scales when force is applied.
authors.affiliation: Top Institute Food and Nutrition (TIFN) , Post Office Box 557, 6700 AN Wageningen, Netherlands.|Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University , Post Office Box 17, 6700 AA Wageningen, Netherlands.
authors.forename: V
authors.initials: V
authors.lastname: Urbonaite
authors.affiliation: Top Institute Food and Nutrition (TIFN) , Post Office Box 557, 6700 AN Wageningen, Netherlands.|ProtIn Consultancy , Nepveulaan 112, 3705 LG Zeist, Netherlands.
authors.forename: H H J
authors.initials: HH
authors.lastname: de Jongh
authors.affiliation: Top Institute Food and Nutrition (TIFN) , Post Office Box 557, 6700 AN Wageningen, Netherlands.|Laboratory of Physics and Physical Chemistry of Foods, Department of Agrotechnology and Food Sciences, Wageningen University , Post Office Box 17, 6700 AA Wageningen, Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van der Linden
authors.affiliation: Top Institute Food and Nutrition (TIFN) , Post Office Box 557, 6700 AN Wageningen, Netherlands.|NIZO Food Research , Post Office Box 20, 6710 BA Ede, Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: Pouvreau
mesh_terms: D006358:Hot Temperature; D066329:Protein Aggregates; D012965:Sodium Chloride / Q000032:analysis; D030262:Soybean Proteins / Q000737:chemistry*; D014867:Water / Q000032:analysis*
chemical_list: D066329:Protein Aggregates; D030262:Soybean Proteins; D014867:Water; D012965:Sodium Chloride
keywords: aggregate density; aggregate size; confined water; entrapped water; soy protein aggregates