Tomato Pomace Ketchup: Physicochemical, Microbiological, and Sensory Characteristics

Tomato (Solanum lycopersicum L.) is one of the most important crops that is extensively used in the food processing industry. During tomato processing, abundant by-products such as skins, pulps, seeds, and waste are generated and cause environmental burdens. To solve this problem, tomato pomace was subsequently used as a material for making tomato sauce. However, it is essential that the production of tomato ketchup meets the required standards. Therefore, it is important to analyze the physicochemical and sensory characteristics of the product. We aimed to study the effect of corn starch addition on the physicochemical and sensory properties of tomato ketchup made from tomato waste and to assess the acceptability of tomato sauce formulated with different concentrations of corn starch. Tomato ketchup was cooked at 90°C for 15 min and then hot-filled into a sterile glass bottle. It was then analyzed for physical properties (color, viscosity, and total dissolved solids), chemical properties (pH, titratable acidity, moisture content), microbiological quality (total bacteria, mold, and yeast), and sensory acceptance. The results showed that corn starch influenced the color characteristics of the tomato sauce. Adding more than 4% of corn starch increased the viscosity and total solids content significantly (p < 0.05). Also, corn starch addition decreased the water content and acidity, as well as increased the pH of the tomato sauce. Microbiological analysis showed no growth of bacteria, mold, or yeast in any of the test samples. According to sensory analysis, the tomato sauce with 1% of corn starch had the highest acceptance, while higher concentrations of corn starch decreased the texture acceptance. Our findings may indicate that, with proper formulation, tomato by-products can be used as raw materials to develop sustainable alternative value-added products that consumers accept organoleptically. Further investigations can be conducted in the pilot-scale studies to enhance the feasibility of tomato pomace ketchup as a commercial product.