Impact of Gamma Radiation Treatments on Emblica officinalis Fruit Juice Powder for Physiochemical, Microbial Load and Antioxidant Properties

Abstract

Introduction: Gamma rays treatment is one of the most common techniques used for microbial control that increases the lifespan of food.
Aim: This study addresses the influence of gamma irradiation on amla fruit juice spray dried powder.
Methods: Amla fruit juice was dried by spray drying technique and further powder was gamma irradiated at different doses i.e., 7-9 kGy, 15-18kGy and 25kGy. Low molecular hydrolysable tannoids, gallic acid, Ascorbic acid were investigated by using HPLC, total tannins and titratable acidity was evaluated by titration method. Identification test was done by TLC and FTIR. Total antioxidant activity was evaluated by DPPH method
Results: There was no change in colour of powder after gamma radiation. At higher dose 15-18 kGy and 25kGy, the powder did not remain in complete free flowing form, some particles of powder agglomerates and form small hard masses. There was no change in FTIR spectra of gamma treated and untreated amla juice powder when analyzed in transmittance mode between 400 and 4000 cm-1. At 25kGy total tannins increased from 33.50 to 35.90%, titrable acidity was decreased from 20.10 to 19.22%, ascorbic acid was also reduced from 4.30 to 4.14%, low hydrolysable tannoids reduced from 21.55 to 21.30% and gallic acid increased from 0.76 to 0.84%. The DPPH activity is slightly increased at 7-9 kGy and 15-18 kGy but decreased at 25kGy. Each of the samples were also tested for total bacterial count. Even after treatment with 7-9 kGy of gamma radiation, the microbial burden decreased significantly.
Conclusion: This study reveals that gamma radiation at 7-9kGy has low effect on phytochemicals, colour, and antioxidant activity, but is extremely significant in reduction of microbial load. Thus 7-9kGy is suitable for treatment to increase shelf life of product.