The effect of heating technique to phytic acid content and antioxidant activity of velvet bean (Mucuna pruriens), butter bean (Phaseolus lunatus) and jack bean (Canavalia ensiformis)

Abstract

Abstract. Pramita DS, Handajani S, Rachmawanti D. 2008. The effect of the heating technique on phytic acid content and antioxidant activity of velvet bean (Mucuna pruriens), butter bean (Phaseolus lunatus), and jack bean (Canavalia ensiformis). Biofarmasi 6: 36-44. Koro is a kind of local bean which has many varieties. The nutrition of koro is not different from soy, especially carbohydrates and protein, which are high enough and have a low-fat content. However, koro also contains some harmful compounds, including, HCN which is poisoned, and phytic acid, an antinutritional compound. Besides being an antinutritional compound, phytic acid has a positive role, i.e., an antioxidant. Besides phytic acid, a legume also contains phenol and vitamin E compounds with antioxidant activity. This research aimed to determine the contents of phytic acid and antioxidant activity and determine the effect of the heating technique on phytic acid and antioxidant activity of velvet bean, butter bean, and jack bean. The materials used were velvet bean, butter bean, and jack bean obtained from Batuwarno, Wonogiri, Central Java. This research used a Completely Randomized Design (CRD) with five kinds of treatment; each treatment consisted of three replications. The treatments given were soaking for 3 days (P₁), steaming (P₂), boiling (P₃), and pressure cooker (P₄), which compared to a raw bean without heating treatment (P₀). The investigated factors were phytic acid and antioxidant activity (DPPH Radical Scavenging Ability method). This research showed that the phytic acid content of velvet bean, butter bean, and jack bean from the treatment of P₀, P₁, P₂, P_3, and P4 were degraded. The phytic acid of velvet bean of P₀, P₁, P₂, P_3, and P4 treatment were 10.87, 8.94, 4.56 and 1.72 and 1.46 mg/db, respectively; on butter bean were 11.78, 8.75, 4.77, 1.73 and 1.61 mg/db, respectively; while on jack bean were 9.04, 1.99, 1.39, 1.42 and 1.21 mg/db. The result of variance analysis showed the phytic acid content was significantly different (p<0.05). The antioxidant activity increased from P₀ to P₁, then the degradation process at P₂, P₃, and P₄. Antioxidant activity at velvet bean were 74.10%, 86.49%, 84.73%, 83.59% and 79.51%, respectively; at butter bean were 4.5%, 7.19%, 6.07%, 6.30% and 6.28%, respectively; at jack bean were 14.64%, 8.55%, 5.84%, 5.17% and 3.58%. The result of variance analysis showed antioxidant activity at velvet bean, and jack bean was significant, while at butter bean for P₁, P₂, P₃, and P₄ were not significant. This research concluded that heating techniques affected the degradation of phytic acid at all kinds of beans used and affected the antioxidant activity at velvet bean and jack bean.