The Structure of Cold-Set Whey Protein Isolate Gels Prepared With Ca++

A technique of combining poly(ethylene-co-methacrylic acid), PEMA, with benzoic acid and sorbic acid to form antimicrobial food packaging material was developed. Heat-pressed film was first modified with NaOH (1 mol/L) or HCl (1 mol/L) and then incorporated with benzoic acid and sorbic acid, respectively, by using acetone as a swelling agent. The incorporation of preservatives into fabricated antimicrobial films was confirmed by characterization of the specific vibrational stretching shown on the IR spectra of the resulting films. Sodium hydroxide and preservative-treated films exhibited dominantly antimicrobial properties in fungal growth inhibition tests, presumably due to the higher amount of preservatives released from the films (75 mg benzoic acid or 55 mg sorbic acid per g of film) than other types of films. Based on the results, we demonstrated that the combination technique with acetone as swelling agent was feasible to manufacture antimicrobial food packaging films.