Comparison study of antioxidant capacity, thermal and pasting properties, and microstructure of germinated and non-germinated pigeon peas flour from the Yogyakarta region of Indonesia

Abstract Pigeon peas are a legume spread throughout various regions of Indonesia and are widely cultivated in the Yogyakarta region. Pigeon peas are a multifunctional legume with higher protein content than adzuki bean, pink bean and chickpea, higher resistant starch levels than mung bean, chickpea and black bean, lower fat content than soybean and cowpea, and have potential as antidiabetic, anti-obesity, and hypocholesterolemic agents due to its phenolic compounds and antioxidant capacities. However, the utilization of pigeon peas in food applications is limited due to their anti-nutrient compounds. Germination reduces antinutrient compounds while increasing antioxidant capacity and modifying the flour characteristics of legume flour. This research aims to determine the effect of germination on alteration in antioxidative capacity, thermal and pasting properties, and microstructure of pigeon peas flour from the Yogyakarta region. The results showed that germinated pigeon peas flour exhibited significantly higher levels of total phenolic compounds and ABTS radical scavenging activity than the non-germinated flour. The lower onset (T o ) and peak temperature (Tp) levels and higher levels of conclusion temperature (Tc) and enthalpy (ΔH) were observed in germinated pigeon peas flour. The germinated pigeon peas flour also showed higher pasting temperature (PT) and peak time (PTime) levels. In contrast, the peak viscosity (PV), through viscosity (TV), breakdown viscosity (BV), setback viscosity (SV), and final viscosity (SV) values were lower than the non-germinated flour. The thermal and pasting properties of germinated pigeon peas flour were in line with its microstructure, which has a smaller starch granule size with an irregular shape, more protein and fiber attached to the starch granule surface and higher cellular material size than the non-germinated flour. The results have significant consequences in modifying thermal and pasting properties, antioxidant, and microstructural characteristics of local legumes flour. This is essential to provide functional ingredients sustainably by utilizing underutilized local legumes.