Optimization of the process for production of mango enriched carrot-tomato ketchup

Abstract

Post-harvest losses of fruits and vegetables in Uganda are estimated at 30% which translates to about 4 billion shillings loss annually. This is due to limited knowledge on value addition and preservation technologies being unaffordable. This study sought to add value to fruits and vegetables with a focus on mangoes, tomatoes, and carrots produced locally. Such fruits tend to get less attention from the fruit processing industries despite their high nutrition value. It this study, the effect of addition of fruits and vegetables on the physico-chemical and sensory properties of tomato ketchup was analyzed. It was also important to determine the effect of processing time and temperature on its rheological properties, shelf stability and nutritional properties. The study was conducted through the replacement of tomatoes with mangoes in the ratios of 0%, 10%, 20%, 30%, 40%, and 50% while keeping carrot levels constant at 5%. The best sensory properties were observed in the treatment that contained 15% mango. The Physico-chemical and sensory properties of ketchup were enhanced by the addition of fruits and vegetables up to 20%. The sensory evaluation revealed that ketchup prepared by the addition of fruits and vegetables (local mangoes and carrots) was preferred as compared to the control sample which was prepared using tomatoes alone. The color of ketchup was affected by the incorporation of mangoes and carrots. However optimum amounts were observed at 5% carrot and 15% mango and the resulting color, taste, appearance, flavor, mouth feel and aroma were acceptable. The best treatment was then subjected to different processing conditions at different holding times and temperatures of 5, 10 and 15 minutes at temperatures of 70, 75, 80, 85, 90 and 100 degrees Celsius respectively. The best temperatures were observed at between 800C and 850C and 10 to 15 minutes holding time. It was also evident that time and temperature had a significant (p<0.05) effect on the Physico-chemical properties of ketchup. The nutritional properties of ketchup decreased with increasing time of processing and temperature. On storage of the ketchup for 90 days under accelerated conditions, there was no significant change in the nutritional aspects of the ketchup. There was no evidence of microbial growth on storage up to one year which suggests that the ketchup is stable on shelves up to one year. I recommend that further research be made to determine how storage affects the quality of ketchup for a period greater than one year under non accelerated conditions.