Long-term stability of compression-molded soybean protein concentrate films stored under specific conditions

CIANNAMEA, EMILIANO M.; ESPINOSA, JUAN P.; STEFANI, PABLO M.; RUSECKAITE, ROXANA A.

FOOD CHEMISTRY

ELSEVIER SCI LTD

Año: 2017

0308-8146

Post-processing evolution of the functional properties of soybean protein concentrate(SPC) films, plasticized with varying levels of glycerol and processed by compressionmolding, was examined over a period of 90 days. Films stored in the glassy state(25±2ºC and 65±2% relative humidity) lost glycerol and water over time, as determinedby gas chromatography and the decline in moisture content. SPC films plasticized with40-50% glycerol showed a time-dependent increment of the elastic modulus and thetensile strength. In turn, the elongation, barrier properties, soluble mass and opacity ofthese films varied marginally with time. By contrast, films with 30% glycerol lost themost moisture and their elongation was reduced significantly, while water vaporpermeability slightly increased with aging. The performance of aged films resulted fromthe balance between plasticizer and water loss, and the progressive replacement ofunordered structures by intermolecular hydrogen bonded b-sheets and aggregates.