Determination of thermal process schedule for acidified papaya.

pH of papaya varies from 4.2 to 5.65 and is required to be lowered to enable processing at atmospheric pressure. A thermal process has been evolved on the basis of inactivation of pectinesterase (PE), the heat resistant enzyme naturally present. Values for thermal inactivation of PE in pulp were F 26.8/212 = 1.04 and D 27/212 = 0.39 at pH 4.0. In a syrup homogenate of 20% total soluble solids, values were F 27.6/207.3 = 1.00 and D 29/207.3 = 0.53 at pH 3.8, and F 27.2/212 = 1.23 and D 27.5/212 = 0.8 at pH 4.0. These F values in syrup homogenate were equivalent to 1.88D at pH 3.8 and 1.53D at pH 4.0. In commercial canning, a 2.5D process at pH 3.8 and 2.0D process at pH 4.0 equivalent to the F values of 1.33 and 1.31, resp., are recommended. Using these F values, process times for different processing, conditions were calculated by graphical method and compared with values found by 3 different procedures of the formula method. The thermal process, thus evolved on the basis of enzyme inactivation, resulted in a safe and acceptable product.