Whey Protein–Tannic Acid Conjugate Stabilized Emulsion-Type Pork Sausages: A Focus on Lipid Oxidation and Physicochemical Features

The purpose of this study was to investigate the oxidative stability and physicochemical properties of pork emulsion sausages with whey protein–tannic acid conjugate and native whey protein. Over the course of 21 days, the thiobarbituric acid reactive substances (TBARS) of sausages containing a whey protein–tannic acid conjugate were lower than those of sausages with regular whey protein (p < 0.05). Kinetically, sausage containing the whey protein–tannic acid conjugate (k = 0.0242 day(−1)) appeared to last longer than sausage containing regular whey protein (k = 0.0667 day(−1)). The addition of the whey protein–tannic acid conjugate had no effect on product texture because there was no difference in hardness, springiness, cohesiveness, or water-holding capacity between the control and treated samples at Day 0 (p > 0.05). Scanning electron microscopy revealed that, at Day 21, the control sausage exhibited emulsion coalescence, as evidenced by an increase in the number of oil droplets and large voids, but not the whey protein–tannic acid conjugate-added sausage. There was no variation in the L*, a*, and b* values of the sausages when the whey protein–tannic acid conjugate was added (p > 0.05). However, there was a little increase in ΔE value in the treated sample. Thus, the whey-protein–tannic acid conjugate appeared to stabilize the lipid and physicochemical properties of the sausages by lowering the rate of TBARS production, retaining texture, water-holding capacity, and color, as well as by minimizing lipid coalescence during refrigerated storage.