Study on Clarification of Apple Juice using Enzymes

Abstract

One of the key challenges in apple juice processing is obtaining a good juice recovery and attaining a juice with good clarity. The presence of pectin and starch components inhibits the juice extraction process and leads to the formation of a cloudy haze which is undesirable in apple juice. For these purposes, maceration enzymes such as pectinase, amylase, cellulose, and hemicellulase are added both before and or after juice extraction to enhance juice recovery percentage and clarify the juice. Process parameters such as type of enzymes used, stage of enzyme addition, incubation time and temperature influence the efficiency of enzymes. The optimisation of these parameters is critically important in apple juice processing for better juice recovery and attaining the desired juice clarity. In this study, juice recovery percentage was compared amongst the control and three treatments- addition of enzyme pectinase at 0.02%, amylase at 0.02% and a combination of both at 0.01%. For the optimisation of process parameters, the type of enzymes used, stage of enzyme addition, incubation temperature, and time were studied as independent variables by comparing with the transmittance value as a dependent variable. Amylase at 0.02%, pectinase at 0.02%, and a combination of 0.01% each of both enzymes were used. The enzyme was added to the pomace and the juice. The treatments were incubated at 200C and 400C. Measurements were done after every 1, 2, 4, and 24 hours of incubation. The juice recovery percentage was not significantly different in the 3 treatments and control where the enzyme was added to the crushed apple. For clarification of apple juice, it is recommended to add the combination of 0.01% each of amylase and pectinase directly to the pomace before juice extraction and incubating the juice obtained at 400C for 24 hours.