Effect of pasteurization methods on physicochemical constituents and optimization of blends for anthocyanin rich guava nectar

Abstract

An investigation carried out to standardize the pasteurization method for the extraction of maximum pulp/juice from guava and grapes and a process for development of anthocyanin rich guava nectar. The pulp of guava variety Allahabad Safeda and juice of coloured grape variety, Pusa Navrang was extracted and used in different proportions for optimization of blends of extracted pulp/ juice from both the fruits for preparation of anthocyanin rich guava nectar without deterioration of guava flavor. Among the different pasteurization methods in respect of irradiation, microwave with 600 W microwave power level, followed by pasteurization at 700C as thermal treatment, found to be the best methods for maximum recovery of the extracted pulp/ juice and nutritional quality over other methods. After pasteurization, the recovery of pulp 62.3%, TSS 14.42oB and ascorbic acid 193.0 mg/100ml was recorded in guava and whereas the juice recovery 68.7 %, TSS (20.53oB), ascorbic acid (6.76 mg/100ml) and anthocyanin content (38.38 mg/100ml) was recorded in coloured grapes, when the fruits were treated with 600 W microwave power level. However, in case of thermal pasteurization at 70oC the recovery of pulp 55.8%, TSS 12.4oB and ascorbic acid 149.33 mg/100ml was recorded in guava and juice recovery 63.0%, TSS (16.47OB), ascorbic acid (6.26mg/100ml) and anthocyanin content (33.48 mg/100ml) was recorded in coloured grapes. With regards to optimization of different blend proportions, for development of anthocyanin guava nectar, a blend of 50:50 of guava pulp and coloured grapes juice was found to be best proportion in preserving the colour, flavour, taste and overall quality of developed anthocyanin guava nectar with having guava dominant flavour.