Determination Of Betacyanin, Anthocyanin And Antioxidant Activity Of Red Dragon Fruit (Hylocereus Polyrhizus) Peel Tea Under Different Pre-Treatments And Drying Conditions

Abstract

Red dragon fruit by-products, which are produced in large quantities and usually thrown away in the food industry, have become a significant environmental problem. This issue may be resolved by converting this waste into valuable goods with attractive physicochemical properties. Thus, this study was carried out to investigate the effect of pretreatment and drying temperatures on physicochemical properties of red dragon fruit peel and sensory evaluation of red dragon fruit peel tea with added sugar types. Dragon fruit peel was blanched with hot water at 90 °C or steamed at 100 °C for 1, 2, 3, 4 minutes before being dried in a hot air oven dryer at 50 °C (for 24h), 60 °C (for 18h), 70 °C (for 12h) and 80 °C (for 8h) and freeze dryer for 72h, -50 °C and 0.001 mbar to reach the moisture content ≤ 10%. Results showed that the amount of anthocyanins, betacyanins content, and radical scavenging capacity of the sample of steamed pretreatment is higher than that of blanching, and the peel steamed for 3 min and dried at 50 °C achieved the highest anthocyanins, and betacyanins content, while the highest result of radical scavenging capacity at drying temperature 70 °C, and steamed treatment 3 min. A red dragon fruit peel tea that developed from the best results of preheating (steam for 3 min) and drying temperature (50 °C for 24h) received customer preference the most with invert sugar type (glucose 50% + fructose 50%). This information provided that red dragon fruit peel is valuable material to manufacture products that have significant health benefits