Mechanical Properties, Water Vapor Permeability, and Moisture Contents of ?-Lactoglobulin and Whey Protein Films Using Multivariate Analysis

• Mechanical and barrier properties of ?-lactoglobulin (?-Lg) and whey protein isolate (WPI) films were studied using sorbitol (S) as a plasticizer. The films were cast from heated aqueous solutions and dried in a climate chamber at 23 °C and 50% relative humidity for 16 h. The multivariate analysis used has proved to be a valuable tool for evaluating and quantifying the influences of the variables in the specified experimental domain. Two identical factorial designs were applied to evaluate the influence of the concentration of ?-Lg and WPI, the concentration of S, and the pH. The two materials, ?-Lg and WPI, show similar results, which can be attributed to the dominating protein ?-lactoglobulin. At pH 9, Young's modulus and stress at break are not affected when the concentration of ?-Lg, WPI, or S varies. At pH 7 and 8, Young's modulus and stress at break increase when the concentration of ?-Lg and WPI increases, and they decrease when the concentration of S increases. Strain at break increases when pH increases from 7 to 9, a more pronounced effect being observed for the WPI films. Water vapor permeability (WVP) decreases and increases for pH 7 and 9, respectively, as the concentration of ?-Lg and WPI increases. This contrast in behavior at different pH values is probably due to a structural difference that occurs above pH 8. Moisture content and WVP increase when S increases. Here a clear distinction can be observed between the two film materials: the ?-Lg films show higher values for both moisture content and WVP measurements.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Livsmedelsvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Food Science (hsv//eng)

Nyckelord

Food Engineering

Livsmedelsteknik

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