Evaluation of antioxidant, antibacterial and physicochemical properties of whey protein-based edible films incorporated with different soy sauces

Abstract

Abstract: Soy sauce is a traditional seasoning for foods available at the global market that is consumed all over the world.This sauce has a uniqueflavor and also antimicrobial and antioxidant properties. There is a wide range of soysauces and their differences are mainly based on the manufacturing methods. Variation in chemical compositionis mainly due to differences in fermentation process and the addition of supplementary ingredients likeflavorenhancers, among others. The present work,firstly evaluated several physico-chemical parameters offivecommercial soy sauces (pH, titratable acidity, acetic acid and potassium sorbate, total solids, total phenol andtotal carbonyl derivatives). In addition, antimicrobial activity of soy sauces in liquid medium was analyzedagainst three food-borne bacterial pathogens, namelyEscherichia coli,Listeria monocytogenesandSalmonellaTyphimurium. Subsequently, whey protein concentrate (WPC)-based ediblefilms were prepared with the ad-dition of soy sauces (5% v/v). Next thefilms were characterized according to physicochemical properties(thickness, moisture content, solubility in water), optical parameters (transparency, color, Fourier transforminfrared spectrum), tensile properties and antioxidant and antimicrobial activities. Our results confirmed thataddition of soy sauces not only improvedfilms organoleptic properties but also conferred antioxidant activityand antimicrobial activity onfilm surface.