Impact of thermo-sonication on antioxidant potential in juices of selected citrus varieties

Citrus is known as a good source of valuable bioactive components and vitamins. In fruit juices, thermal treatments such as pasteurization are usually used for inactivation of enzymes and for destruction of microorganisms. Thermo-sonication is combination of heat (37 to 75 °C) with ultra-sonication treatment has high efficiency for inactivation of microbes and enzymes. The present study aims to develop a new processing technique for citrus juice to improve its functional properties. Variety Succari excelled in terms of average fruit diameter and weight and the maximum number of segments found in Feutrell’s Early. The highest acidity value was observed in T0 (0.251±0.008 %) and the lowest in T1 (0.147±0.002 %) juice of Kinnow. Acidity value was decreased by application of pasteurization. Total phenolic contents of Musambi juice showed significant increase in thermo-sonicated and sonicated juice in comparison to non-sonicated juice. The increase was high in T4 (458.89±6.72 µg/mL of GAE) and T5 (450.37±9.83 µg/mL of GAE). Antioxidant activity showed significant increase in thermo-sonicated and sonicated juice. The increase was high in T5 (1,103.20±9.94 µg/mL of ascorbic acid equivalent) and T5 (1,110.74±23.67 µg/mL of AAE) in juice of Kinnow. Total plate count showed significant reduction in thermo-sonicated (T4) and in combined treatment of chemically preserved and pasteurized (T3) juice in comparison to sonicated (T5) and non-sonicated (T1 and T2) juice. The minimum decrease of total plate count was found in juice of Feutrell’s Early while maximum reduction was checked in the juice of Musambi during storage.