Optimization of drying parameters for cactus fruit in hot air tray drier

Abstract

Cactus fruit (Prickly pear) is popular for its medicinal properties and health benefits. Cactus fruit is used for anti-diabetic effect, anti-cancerous effect, antiviral effect, anti-inflammatory effect, and hypercholesterolemia effect. It is a rich source of minerals like iron, calcium and potassium, vitamins, and antioxidants like betalains. It is necessary to preserve the vitamins, antioxidants, and bioactive compounds of nutritive fruit. Hot air drying is a common method for preserving such fruits with their compounds. Steam blanching is used as a pre-treatment to inactivate enzymes and improve the quality of the final dried product. Proximate, chemical and nutritional compositions were analysed for cactus fruit and mint. Steam blanching treatment was used for inactivation of PME (Pectin-methylesterase) enzyme, which is responsible for the hydrolysis of pectin. Steam blanching was carried out at 96±2 °C for the enzyme inactivation. After blanching, cactus fruits were dried in hot air dryer at three different temperatures (45, 50, 55 °C) till it achieved 7% moisture (w.b.) and drying time for each temperature was recorded. The temperature for drying was selected on the basis of minimum drying time, maximum total betalain content and maximum total antioxidant activity. Cactus fruit contained 30.44±0.1 mg/100 g of total betalain content, 10.25±0.06 mg/100 g of vitamin C, 40.21±0.05 mM/100 g of total antioxidant activity, 1.87 mg/100 g of iron, 563.20 mg/100 g of calcium, 51.80 mg/100 g of phosphorous, 485.80 mg/100 g of potassium and 175.60 mg/100 g of magnesium and 1.11±0.04 % of protein. Hot air drying temperature of 50 °C was optimized based on statistical analysis.