PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Red pitaya fruit and peel have been widely explored for food products due to their functional properties. However, the stem still has limited use. This work was aimed to determine the proximate and phytochemical properties of red pitaya stem by processing it as flour and applied it as food products. The different drying temperature (40, 50, 60°C) on the flouring process was conducted to determine the best drying condition. The best drying temperature was then used to prepare the flour by using whole stem (epidermis and cortex) and peeled stem (cortex only). The result showed that the effective drying temperature on the flouring process was 60°C. The predominant component in the whole and peeled stem flour was fiber (total of hemicelluloses, cellulose and lignin), which contained up to 50.4% and 43.03% respectively. The second largest component was protein which the whole stem flour contained 9.09% of it and the peeled stem flour contained 11.97% of it. Both of the flour contained high vitamin C (3.64–3.76%) and phenolic compounds (43.55–44.54 mg/g). Either whole or peeled stem flour showed antioxidant activity up to 91% of inhibition and antibacterial activity against Escherichia coli, Staphylococcus aureus as well as Salmonella typhi. The resulting flour has been successfully applied as substitute and additional ingredients to make fiber enriched food products.