Effects of natural extract mixtures on the quality characteristics of sausages during refrigerated storage

Owing to the residual toxicity and adverse health effects of chemical preservatives, there is an increasing demand for using natural preservatives in food. Although many natural extracts have been evaluated, research on their antibacterial effects remains insufficient. Therefore, this study aimed to explore the possibility of developing Psidium guajava, Ecklonia cava, and Paeonia japonica (Makino) Miyabe & Takeda extracts as natural food preservatives. Further, the effect of mixing these extracts on microbial growth and quality was evaluated during the refrigeration of sausages. The antibacterial activity was evaluated against three pathogenic bacteria (Listeria monocytogenes, Salmonella spp. and Escherichia coli). The optimal mixing ratios were determined based on the minimum inhibitory and bactericidal concentrations of each mixed extract. D-optimal mixing design optimization tool was further used to obtain an optimum mixing ratio of Formulation 1 (F1). The antibacterial activity of F1 increased with increasing concentration, with similar activities at 0.5 and 1%. The sausages with synthetic or natural preservatives showed significantly lower lipid oxidation than those of the control and grapefruit extract-treated sausages after 4 weeks of storage. Total plate counts were observed only in the control and treatment group stored for 3 weeks. Compared to the other samples, sausages with added natural extracts showed the highest overall acceptability scores initially and after 4 weeks. Therefore, similar amounts of grapefruit seed and natural extracts had the same effect on microbiological analysis and lipid rancidity during sausage storage. Hence, this mixture can serve as a potential natural preservative in meat products.