The potential of pulsed light treatment to produce enzymatically stable Indian gooseberry (Emblica officinalis Gaertn.) juice with maximal retention in total phenolics and vitamin C

The impact of pulsed light (PL) treatment conditions on color profile, antioxidant activity, phenolics, vitamin C content, polyphenol oxidase (PPO), and peroxidase (POD) activity in Indian gooseberry (amla) juice was explored. The juice was extracted mechanically from the raw fruits. The intensity of PL varied from 1,504 to 3,012 J center dot cm(-2), and complete inactivation of both PPO and POD was obtained at 2.9 kV for 5 min (3,012 J center dot cm(-2) at 10.04 W center dot cm(-2)). The thermal treatment of 95 degrees C/3 min also inactivated PPO and POD completely but resulted in a brownish sample (browning index, BI = 62.73) than PL-treated (BI = 58.33-60.83) and untreated samples (BI = 58.97). The PL treatment at 2.9 kV for 5 min (3,012 J center dot cm(-2)) was the best to produce enzymatically stable amla juice with 45, 54, and 61% more retention in total phenolics, antioxidants, and vitamin C content, respectively than the thermally pasteurized sample. Practical applications The browning of Indian gooseberry (amla) juice after preparation and during storage is one of the critical issues in the industry. The enzymes such as polyphenol oxidase and peroxidase are responsible for this type of browning and off-flavor in the juice. Therefore, processing of amla juice while assuring the maximal retention of color and phytochemicals is of great interest. The pulsed light (PL) processing can simultaneously inactivate the enzymes as well as microorganisms while retaining the nutrients in the beverage. The study establishes that PL treatment of 5 min at 2.9 kV (3,012 J center dot cm(-2)) can serve as an alternative to conventional batch pasteurization for amla juice when retention of color and bioactive compounds is one of the major concerns.