Formulation and Physicochemical Characterization of Composite Flour from Yam (Dioscorea alata) and Lima Beans (Phaseolus lunatus)

Wheat flour consumption in Indonesia increases annually and this condition may threaten the national food security. Moreover, excessive wheat flour consumption also has some negative health effects due to gluten. On the other side, Indonesia is rich in local food sources that have potential to be developed and national food security can be strengthen. Flour production is one of the best alternative ways to be selected as the downstream stage of the tubers and legumes utilization. Yam and lima beans are examples of Indonesian tubers and legumes that could be developed as materials for composite flour production. The objective of this study is to determine the best formula of composite flour from yam and lima beans based on their physicochemical characteristics. Physical and chemical analyses were conducted and completely randomized design was used. Three different formulations were developed. The ratio of yam flour and lima beans flour, which were 85: 15 (F1), 70: 30 (F2), 55: 45 (F3) respectively, were formulated to produce composite flour. The results showed that F1 demonstrated the highest level in oil holding capacity (1.168 +/- 0.009 g/g), water absorption (75.553 +/- 0.139%), mineral (ash content) (4.054 +/- 0.019%), carbohydrate (76.369 +/- 0.094%), amylose (29.824 +/- 0.003%), antioxidant activity (69.650 +/- 0.705%) and total phenolic compound (1.326 +/- 0.002%). On the other hand, F2 have the highest starch content (71.772 +/- 0.170%) and amylopectin content (42.136 +/- 0.175%). While F3 has the brightest color of composite flour (oHue = 78.434 +/- 0.123), the highest level of swelling ower (7.228 +/- 0.127 g/g), water holding capacity (2.293 +/- 0.000 g/g), highest protein content (12.928 +/- 0.052%), fat (0.782 +/- 0.001%), dietary fiber (12.942 +/- 0.109%) and resistant starch (17.591 +/- 0.111%) respectively. The highest effectiveness index of three formulas was further evaluated by De Garmo analysis. F1 showed the highest effectiveness index (0.533) among three formulas developed in this study. Therefore, formula (F1) was selected as the best composite flour from yam and lima beans.