Extraction of Pectin from Lemon ( Citrus limon L.) fruit peels and its utilization in the Production of Watermelon ( Citrullus lanatus) Jam

Abstract

Citrus fruits peels are very rich in pectin and can be used as source of pectin for its commercial production. Moreover, the citrus fruit peels contained several bioactive compounds, including carotenoids, essential oils, antioxidants and flavors are widely incorporated into food products in order to enhance their sensory properties and to improve their nutritional and health benefits. Therefore, aim of this study was to make use of lemon peels as a source of pectin in making watermelon jam along with different levels of sugar and pectin. Pectin was extracted from lemon peel by acid extraction method at pH 1.5, 80℃ for 1 hour. The physico-chemical, sensorial and microbiological properties of the formulated jam were assessed using standard AOAC methods. The physico-chemical analysis of freshly made watermelon jam revealed that an increasing trend in titratable acidity from 0.27 to 0.61% (as citric acid), moisture from 52.9 to 63.1% and decreasing trend in pH from 3.95 to 3.31 and total soluble solids from 68.1 to 66.1°Brix when the pectin levels increased from 1.8 to 3.3 g per 500g watermelon pulp. According to Kruskall-Wallis Method the mean scores of the sensory qualities in terms of color, taste, texture, aroma and overall acceptability varied significantly (p<0.05) in the freshly formulated jam. There were no significant (p>0.05) differences between in total plate count of all treatments. The results of this study revealed that the watermelon jam formulated with 65g of sugar, 2.8g of pectin and 500g of pulp was the best combination and it could be stored at 30±1℃ for 12 weeks without any significant changes in the quality characteristics. Therefore, pectin which was extracted from lemon peels can be used as an effective food additive in watermelon jam production.