Extending spring roll sheet shelf life against microbial spoilage using preservative combinations

High water activity (aw) and low-acid foods are rapidly spoiled by microorganisms. The preservative was widely used to extend the microbial shelf life of foods. The suitable preservative combinations were potential microbial inhibition/killing because of their synergistic effect, multiple anti-microbial actions, and broad anti-microbial efficacy, enhancing longer shelf life even with a reduced preservative concentration. A spring roll sheet has a short shelf life (2–3 days) because of its high moisture content (~40%) and aw (~0.99), which makes it susceptible to microbial spoilage. Extending this short shelf-life is necessary for commercial use. This study extended the shelf life of spring roll sheets stored at room temperature (27–29°C) before microbial spoilage. The process investigated the suitability of using a combination of tartaric acid (T) and potassium sorbate (S)/ calcium propionate (P)/mixture of S and P (M) with varied concentrations and in regulated concentrations following the CODEX standards for food additives as preservatives with efficient contents for storage time extension. The advantages of preservative combinations were efficient in broadly inhibiting/killing microorganisms, and the potential for a longer shelf life of the treated product. The experimental preservatives did not affect the moisture content or water activity compared to the control samples (without preservatives); however, the control was adversely affected by rapid microbial spoilage. The higher concentration of T (0.27%) more efficiently enhanced the efficacy of the added S, P, and M to inhibit microbial growth than the lower concentration (0.19%). Only the combination of T (0.27%) with S (0.10%) and the combination of T (0.27%) with a mixture of S (0.05%) and P (0.05%) were efficient as preservatives to extend the shelf life of the spring roll sheet to more than 12 days, which was 4 times the shelf life of the control sample. These suitable preservative combinations inhibited the dominant microbe causing spoilage of the target products, resulting in efficient extension of the shelf life of the product, even though less preservative contents were used. The preservative contents in the spring roll sheet samples were 3.4–7.3 times lower than the maximum permitted levels in CODEX Alimentarius Commission (2023).