Physical Properties of WPI Films Plasticized with Glycerol, Xylitol, or Sorbitol

Abstract

Effects of glycerol, xylitol, and sorbitol on selected physical properties of whey protein isolate (WPI) films were examined. Increasing glycerol or sorbitol content led to increases in moisture content, water vapor permeability, and % elongation; and decreases in tensile strength, elastic modulus, and glass transition temperatures of the films. Increasing levels of xylitol had no effect on permeability, moisture content, or glass transition temperature of the films, but decreased % elongation, tensile strength, and elastic modulus. Moisture content of the films correlated well with glass transition temperatures. Differences in measured physical properties of films with plasticizer type and concentration may be attributed to differences in the hygroscopic and crystalline properties of the plasticizers.

Physico-Chemical, Functional and Rheological Characterization of Biodegradable Pellets and Composite Sheets

“…Similar behaviour of glycerol has been observed in films developed using glycerol as plasticizer due to the hygroscopic character of plasticizers [20][21]. A significant change in water binding capacity was observed among the raw materials and the pellets formed.…”

Development and characterization of edible films based on gluten from semi-hard and soft Brazilian wheat flours (development of films based on gluten from wheat flours)

“…For all the films with 15% glycerol, the values for solubility in water were not significantly different (P<0.05) and the lowest value was observed for the film with gluten from EMBRAPA 42 wheat flour ( semi-hard ). Increasing the amount of plasticizer, specially glycerol, caused an increase in moisture and WVP of the WPI (whey protein isolate) films [38]. This is probably due to the plasticizer that disrupts intermolecular interactions between polymer molecules [27].…”

“…Significant differences in solubility in water for the films with higher concentration of glycerol were observed in the following order ( Table 2): soft wheat > semi-hard wheat > vital gluten. Considering that glycerol is infinitely soluble in water [38], differences in solubility can be occurred due to the difference on the intensity of the polymer association, where films from soft wheat were not able to prevent the glycerol loss from the matrix to the aqueous solution. With lower concentration of glycerol, the solubility of the films was lower and there was no significant difference between all the films tested, indicating that the polymer matrix was able to partially accommodate and protect the polyol loss through the solution.…”

Recobrimento de laranja 'Pêra' com filme de concentrado protéico de soro de leite associado a plastificantes

“…Os filmes constituem barreiras à perda de vapor d'água e à troca gasosa, além de serem materiais de embalagens biodegradáveis (Shaw et al, 2002).…”

“…A formação de filmes provenientes de hidrocolóides necessita de um biopolímero, para promover a matriz estrutural, e de um plastificante de baixo peso molecular, para aumentar a flexibilidade do filme (Shaw et al, 2002). Plastificante é uma substância não-volátil que, quando adicionada a um material altera suas propriedades mecânicas e/ou físicas.…”