EFFECT OF MICROWAVE PRETREATMENT ON QUALITY CHARACTERISTICS OF REFRACTANCE WINDOW DRIED ORANGE PESTIL

Abstract

The goal of the current investigation was to determine how microwave pre-treatment affected Refractance window drying of orange pestil based on its quality criteria like colour, ascorbic acid, total phenolic content, antioxidant activity, and rehydration ratio. Orange pulp was treated with microwave power levels of 300 W, 450 W, and 600 W at 70, 80, and 90 °C with two pulp thickness of 2 mm and 3 mm. The findings demonstrated that as the power level of microwave for pre-treating orange pulp increased the Refractance window drying colour parameters L* decreased, with the decrement ranging from 6.7% to 14.90%, a* increment ranging from 10.0% to 43.8%, and b* value decrement ranging from 17.7 to 23.60%. The dried and pre-treated samples were dark and crimson. A rising trend was observed in total phenolic content and antioxidant activity as microwave power level raised but ascorbic acid concentration declined with increasing microwave power level, declining from 19.71% to 25.91%. The highest reported total phenolic content was 40.90 mg GAE/g, and the lowest value was 28.20 mg GAE/g. In terms of their ability to scavenge diphenyl-2-picryl hydrazyl (DPPH) radicals, produced orange pestil’s antioxidant activities improved. The maximum and minimum antioxidant activity concentrations were reported to be 87.70 µmol/g and 78.80 µmol/g, respectively. At increased microwave power, a reduced rehydration ratio was seen. The lowest rehydration ratio was 3.97, and the highest rehydration ratio was 5.03. Therefore, it can be inferred that a 600W microwave set at 70 °C might be used to treat orange pulp with a thickness of 2mm, protecting some specific nutrients while also increasing the pulp’s overall total phenolic content and antioxidant activity