Nutritional, Compositional and Antioxidant Properties of Tropical Almond (Terminalia catappa) Press Cake Flour

Food processing industry generates great volume of economically valuable waste. The protein rich press cake produced during the screw press extraction of tropical almond (Terminalia catappa) is also a potential ingredient in numerous food items. This study aimed to utilize tropical almond press cake (TAPC) to produce a gluten free flour as an alternative for whole wheat flour having the concern on zero waste concept of circular economy. The TAPC was dried at 60^oC and pulverized in to a flour using micro-pulverizer. The proximate composition, gluten content and elemental composition was analyzed by AOAC 2005 method, wet gluten test and ICP-MS respectively. Further, Scanning Electron Micrograph (SEM) structure, bioactive compounds and antioxidant capacity of the flour were evaluated. According to the proximate data, the flour showed high protein content (41.94±1.22) with 6.80±1.01, 6.99±0.78, 8.66±0.89, 5.71±1.48 and 28.90±0.79 g/100 g of moisture, ash, crude fat, crude fiber and carbohydrate respectively. The TAPC flour showed 335.52±1.87 kcal/100 g of calorific value and zero gluten content. Further, the flour showed high K (189.25) and Ca (618.75) content with 70.62, 43.52,12.30 mg/100 g of Na, Fe and Zn respectively. The irregular shaped unevenly distributed starch molecules were visible in SEM image of the flour and their surfaces were not smooth. The total phenolic (136.83 mg GAE/100 g) and flavonoid content (188.63 mg QE/100 g) of the TAPC flour were significantly higher compared to the tropical almond nut (64.31 mg GAE/100 g and 133.8 mg QE/100 g). Moreover, TAPC flour showed high antioxidant activity with an IC₅₀ of 37.86±3.44 mg/ml for DPPH, 8.24±1.23 mg/ml for ABTS, and a reducing power of 402.50±0.33 mM Trolox eq/100 g in FRAP assays. Hence, the TAPC flour could be a high protein, gluten free natural flour with potential nutritional and antioxidant properties to be used as an alternative for wheat flour in food products.