Production and properties of edible film using whey protein
The utilization of exces whey is necessary to reduce dairy waste because the large amount of whey disposal in waste streams has caused environmental problems. During whey protein film production as the effective means of utilization of excess whey, we have examined the effects of pH, temperature, and plasticizers for water vapor permeability (WVP), tensile strength (TS), and elongation rate (%E) of the whey protein films. The 10% whey protein films had the highest WVP (28.73 g·mm/kPa·day·m2) and TS (1.85±0.11 Mpa). But, in this case, an increase of WVP was caused by the thickness of whey protein films. At the concentration of 8% whey protein, appropriate thickness was obtained. Whey protein films prepared at the pH 6.75 and 95°C showed lower WVP (28.38 g·mm/kPa·day·m2) and elongation rate (12.9%) and higher TS value (3.769±0.407 MPa) than at the pH 6.75 and 75°C. As the temperature increased, WVP of films decreased slightly and tensile strength increased slightly, while elongation rate decreased significantly. Higher WVP and TS were observed at pH 6.75 compared to pH 7–9. In contrast, significantly higher elongation was observed at pH 9 compared to pH 6.75–8. Among the plasticizer type used, the addition of sorbitol showed the highest TS value (6.244±0.297 MPa) at the concentration of 0.4 g sorbitol and elongation rate (49%) at the concentration of 0.6 g sorbitol.
Key wordswhey protein water vapor permeability tensile strength elongation rate
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