Effect of Different Dried Methods and Storage on Some Enzymes Activity and Quality of Cactus pear and Papaya

Abstract

This study was to evaluate the activity of peroxidase, polyphenoloxidase, pectin methyl esterase and protease as well as the proximate chemical composition and quality parameters of cactus pear and papaya which were dried by different methods and stored for 6 months. Our findings revealed that the highest moisture content was recorded in osmo – freeze drying of papaya and cactus pear. On the other hand, the browning index of oven dried papaya and cactus pear was higher than those dried with osmotic dehydration and osmo – freeze drying. The less activity of peroxidase was recorded in osmo – freeze drying of papaya and cactus pear. Also, the highest reduction of polyphenoloxidase activity was noticed in osmo–freeze drying methods. While oven dried papaya recorded the highest activity of pectin methyl esterase pectin (0.34 %), complete inactivation was shown in other dried methods after 6 months of storage at 4 ±1℃. Different dried methods of papaya caused to reduce the activity of protease; moreover, complete inactivation was observed after 3 months from storage. The quality parameters for sensory evaluation of dried cactus pear and papaya demonstrated that osmo–freeze drying was more favorable to preserve samples followed by osmotic dehydration and oven drying