Assessment of the shelf life of a tomato sauce by incorporating a combination of artificial preservatives with natural preservatives

Abstract

Tomatoes, rich in essential nutrients, are extensively cultivated in Sri Lanka, yet local tomato sauce production relies heavily on imported pulp preserved with artificial additives. This research aims to address this issue by developing a preservative strategy that enhances shelf life using a combination of natural and synthetic preservatives. The primary objectives are to evaluate the physicochemical properties of tomato sauce made from locally grown Pathma tomatoes, investigate the effects of combining preservatives, and provide recommendations to the National Institute of Post-Harvest Management. The methodology includes preparing tomato sauce using natural and artificial preservatives, followed by Sensory evaluations (using a 7-point hedonic scale). Total plate count (TPC), and yeast and mold counts (YMC) were conducted bi-weekly to evaluate shelf life and quality. Data were analyzed using the Friedman test for sensory attributes and ANOVA for microbial and physiochemical properties from MINITAB 16. This study evaluates the impact of different preservative treatments and storage conditions on the sensory qualities, color stability, total soluble solids (TSS), and microbial load of tomato sauce. Five treatments were tested: potassium sorbate at 300 mg/kg and 500 mg/kg, a natural preservative, a market sample, and a control. Sensory evaluations revealed that the market sample scored highest in color (6.2), aroma (6.0), and overall acceptance (5.8), indicating consumer preference. Color stability analysis showed that the market sample had the highest mean color value (25.36 ± 0.035) at room temperature. Natural preservatives in treatments had the highest TSS values (42.00 ± 0.00), and the highest TPC at room temperature (79.1 ± 38.2). The YMC was lowest in samples treated with both natural and artificial preservatives. The findings suggest that the choice of preservative significantly affects tomato sauce quality, with artificial preservatives maintaining better sensory and microbial stability. These results provide a basis for selecting preservative strategies to enhance product quality.