ENZYMATIC PRE-TREATMENT IN RED BEET JUICE PRODUCTION: THE EFFECT OF PROCESS VARIABLES ON JUICE YIELD, BETANIN CONTENT, TOTAL PHENOLIC COMPOUND AND ANTIOXIDANT CAPACITY

Red beet is the most important source of betanin, a natural colorant commonly used in the food industry. The first production step for this food colorant presented in concentrated or powder form is the production of red beet juice. The aim of this study is to determine the effect of enzyme pre-treatment prior to pressing step in the production of high-yield red beet juice and, that of pH, temperature, enzyme ratio and processing time. In this context, the effect of enzyme addition (Pectinex Ultra SP-L) were evaluated at different pH values (2.5-5.0) and temperature (30-60 °C); and in the second step, the effects of the enzyme ratio and processing time were determined using the response surface methodology (RSM). Enzyme pre-treatment increased press yield by 17%. Under the optimum conditions which are 3.0 pH value, 50 °C temperature, 75.8 polygalacturonase unit (PGB)/g enzyme ratio and 48 min processing time, the fruit juice yield was 34.7%, the betanin content was 106.0 mg/100 g, the total phenolic content was 245.2 mg GAE/100 g and the antioxidant capacity was determined as 47.0 μmol TE/100 g