Effect of pretreatment and different drying methods on the antioxidant activities and physicochemical properties of bitter gourd powder

A study was conducted to determine the effect of pretreatment and different drying methods on the antioxidant activities and physicochemical properties of bitter gourd powder. The treatments used were: Un-blanched: (no treatment), hot water blanching (80oC for 5 min), potassium metabisulphite treated (KMS 0.4% for 5min) with three drying methods viz., sun dry (72 h), oven dry(65oC 24h), micro oven dry (500 w for 5 min). The result revealed that the maximum phenol content (16.44, 14.38 and 12.53 mg/100g GAE) and total carotenoid content (25.55, 22.58 and 21.41 mg/100g) was in KMS-treated micro oven dried treatment at 1, 2 and 3 months after storage respectively. However, vitamin C (20.48.19.06 and 17.93mg/100 g) and DPPH scavenging activity (90.65, 84.42 and 81.14 %) was found in KMS-treated oven-dried treatment at 1, 2 and 3 months after storage, respectively. It can be concluded that KMS-treated microwave-assisted convective drying of bitter gourd reduced loss of quality attributes while retaining better color and quality characteristics.