Whey protein isolate edible coatings: Effect on the rancidity process of dry roasted peanuts

Dry-roasted peanuts were coated with whey protein isolate (WPI)/glycerol solutions. Accelerated rancidity tests of uncoated and coated nuts were performed. Coating thickness and environmental relative humidity were studied as factors that affected rancidity. In addition, the effect of limiting the amount of WPI solution absorbed by the nutmeat on the performance of the coating was evaluated. WPI/glycerol edible coatings delayed the oxidative deterioration of dry-roasted peanuts. Greater thickness and lower relative humidity resulted in more effective coatings. Therefore, the mechanism of protection of the coatings relies on its properties as an oxygen barrier. The continuity of the coating was shown to be critical for its effectiveness. In addition, limiting the WPI solution migration into the nutmeat did not improve the effectiveness of the WPI coating.