Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2005
Publication Date: 7/1/2005
Citation: Siddiq, M., Khan, A.A., Harte, J.B., Dolan, K.D., Collins, J.K. 2005. Effect of processing methods on the lycopene content, physico-chemical characteristics and sensory quality of watermelon juice. 2005 Annual Meeting of the Institute of Food Technologists. Paper No. 36E-17.
Technical Abstract: Watermelon is rich in lycopene, a carotenoid that is thought to have a protective effect against certain cancers and cardiovascular disease. The consumption of watermelon has risen steadily in recent years; it increased about 60% between 1980 and 2000. However, currently it is consumed mainly in its whole or fresh-cut form. There is a need to develop processing methods for watermelon juice/concentrate that have minimal effect on lycopene degradation, physico-chemical characteristics, and sensory quality. Our objective was to develop a method of processing watermelon juice that maintains a palatable product while optimizing lycopene content, and obtaining favorable consumer acceptance. Whole seedless watermelons were purchased from a local source, washed and sanitized in160 ppm chlorine dip. Fruit was manually peeled and cut into approx. 2-inch chunks and mashed using a propeller-type blender. Juice was pressed from cold macerate (I), hot macerate--50 C for 30 minutes (II), and hot macerate as above treated with 0.01% commercial pectinase (III). Juice was evaluated for lycopene contents, TSS, pH, titratable acidity, juice clarity and Hunter color “L” “a” and “b” values. A small trained panel evaluated juice based on sensory attributes of color, aroma, flavor, mouth feel, and taste. Highest juice yield (86%) was obtained with process III, followed by II and I. Heating of macerate resulted in 18% lower lycopene contents in the juice. Method of juice extraction had little or no effect on pH, titratable acidity and Hunter color “L” or “b” values. However, juice from process I had higher “a” values, i.e. more red in color. Pasteurization of juice resulted in a slight decrease in lycopene contents. Addition of 0.15% gum acacia improved juice stability. Based on the physico-chemical analysis and sensory scores, it is concluded that juice pressed from cold macerate (I) was better in quality than from the other methods used.