Effects of Lactobacillus plantarum-fermented soy whey composite/huajiao seed antimicrobial peptides/inulin composites on konjac gel preservation

Abstract

To extend the shelf life of konjac gels, this study investigated the effects of preservatives prepared using food production byproducts. First, the ultrasonic and microwave-assisted extraction of huajiao seed protein (HSP) was performed using the following process parameters: ultrasonic power of 90 W, ultrasonic time of 1 min, microwave power of 100 W, and microwave time of 1.5 min. The HSP extraction rate under this parameter reached 56.36 ± 1.91 %. The huajiao seed antimicrobial peptide (HSAP) obtained via enzymatic hydrolysis of the HSP inhibited Escherichia coli and Staphylococcus aureus by 20.26 ± 3.79 % and 28.97 ± 4.00 %, respectively. HSAP was mixed with Lactobacillus plantarum-fermented soy whey (LPFSW) and inulin to develop an LPFSW composite preservative for konjac gel preservation. The selected LPFSW composite preservative exhibited excellent moisturizing properties and was stable at 4 °C for 10 d with inhibition rates of 96.85 ± 0.45 % and 94.94 ± 1.57 % against E. coli and S. aureus, respectively. In addition, at 4 °C, the LPFSW composite preservative was able to control the weight loss rate of the konjac gel to < 10 % in 8 days and maintain its textural properties, appearance, and odor. In summary, the LPFSW composite preservative was effective in preserving the konjac gel, extending its shelf life from 2 to 8 d.