Storage-induced changes in plasticizer emigration and structural properties of soybean isolate protein-based composite films

Abstract

Previous study found soybean isolate protein (SPI)-based composite films added by corn starch (CS) (SPI:CS (4:1) composite film, SPI:CS (1:1) composite film) exhibited good mechanical property and better stability during the short-term storage pre-experiment. These properties were related to internal structure changes. In order to accordingly understanding the causes driving stability changes in performance and then controlling long-term stability of the SPI-based composite films, plasticizer emigration and structural properties of SPI-based composite films stored at different temperatures (5 ℃, 20 ℃, 35 ℃) and 54% relative humidity were systematically investigated over a period of time. High storage temperature (＞ 20 ℃) accelerated plasticizer emigration which reflected in increased migration rate of glycerol molecules and decreased moisture content. During the storage of SPI-based composite films, the decreased free SH partly formed new disulfide bonds and non-covalent inter-molecular interactions like hydrogen bonds changes significantly weakened the protein structure, which influenced mechanical properties changes during storage. PAGE and FTIR results explained the protein aggregation was bond with disulfide bonds and the reorganization of protein structure with prevalence of extended β-sheet conformation.

Protein‐based active films: Raw materials, functions, and food applications

“…The addition of plasticizers to proteins can lead to changes in their three‐dimensional structure, where plasticizers enter between protein molecular chains and join proteins through physical interactions and chemical reactions, resulting in increased ductility, flexibility, and elasticity and decreased mechanical properties, cohesion, and stiffness (Ananey‐Obiri et al., 2018). Currently, plasticizers, such as those made from soy protein isolate (Zhu et al., 2023), corn protein (Baloyi et al., 2023), milk protein (Stefano et al., 2023), and whey protein isolate (Mariana et al., 2022), have been used in protein‐based packaging films, and good results have been obtained. Water is the most used best‐performing plasticizer in the preparation of protein films.…”

Manufacture of Edible Films from Wheat Germ Protein and Study of its Mechanical Properties

“…Some studies have been conducted at temperatures higher than the surrounding air temperature (about 23°C). Take into account the dried multilayer film of fatty acids and hydroxypropyl methylcellulose produced with [18] at 90 °C for 15 min. and the dry soymilk protein films made with [18] at100 C° for 1h.…”

“…Take into account the dried multilayer film of fatty acids and hydroxypropyl methylcellulose produced with [18] at 90 °C for 15 min. and the dry soymilk protein films made with [18] at100 C° for 1h. as examples.…”