EVALUATION OF A THERMAL PROCESS FOR ACIDIFIED CANNED MUSKMELON (Cucumis melo L.)

Abstract

ABSTRACTThe pH of muskmelon varies from 5.3–6.1 and is required to be lowered to ensure an organoleptically acceptable and microbiologically safe canned product. Thermal process has been evolved on the basis of inactivation of peroxidase and pectinmethylesterase (PME), the heat resistant enzymes, naturally present. The thermal inactivation temperatures equivalent to the time of 1 min at pH 3.8, 4.0 and 4.2 in syrup homogenate of melon pulp adjusted to 20° Brix were 187, 192 and 194.5°F respectively, with z values of 16.7,17.9 and 17.2 respectively. The thermal inactivation time (TIT) of PME at pH 4.2 was 1 min at 191°F with a z value of 21. Hence, processing time required was evolved on the basis of thermal inactivation of peroxidase. The F values of peroxidase found were equivalent to 2SD, 2.9D and 2.8D at pH 3.8, 4.0 and 4.2, respectively. Initial temperature being 170°F, a 4D process at 207°F corresponding to 6.3, 7.6 and 9.3 min respectively for A 2% (401 × 411) cans at pH 3.8, 4.0 and 4.2 respectively ensured inactivation of the enzymes. No microbiological spoilage was observed and the canned product had good color, texture and full flavor.