Properties and storage stability of whey protein edible film with spice powders

The impact of spice powders on physical, mechanical, thermal and barrier properties, and on storage stability, of whey protein isolate (WPI)-based films was determined. Films with added spices were prepared from casting solution containing 10 % (w/w) heat-denatured WPI, glycerol (WPI:glycerol of 3:2 w/w), sodium chloride (0.4 g/100 g solution), garlic and pepper powders (≤3 g each/100 g solution). Water activity (a_w) of all films was 0.53-0.57. Addition of spice powders increased thickness, darkness and yellowness of the WPI films. Films with added spices had lower tensile strength (TS), percent elongation (%E), and melting enthalpy of WPI matrices, but possessed higher water vapor permeability (WVP) than WPI film without sodium chloride and spices. The WPI film containing highest amount of garlic powder and lowest amount of pepper powder was selected for storage tests at 25-45 °C. Storage for up to 49 days resulted in reduced a_w and %E, increased TS, and color changes at 35 and 45 °C, with few changes at 25 °C. However, film WVP and OP were not affected by storage conditions after 7 days storage. Active ingredients decreased over time with up to 81 % allicin and 37 % piperine retained in the film matrix after 47 days storage.