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

Pramita DS, Handajani S, Rachmawanti D. 2008. 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). Biofarmasi 6: 36-44. Koro is a kind of local bean which has many varieties. The nutrition of koro is not different with soy, especially carbohydrate and protein which high enough, and has a low-fat content. However, koro also contains some harmful compounds, HCN which poisoned and phytic acid which an antinutritional compound. Besides as antinutritional compound, phytic acid has a positive role, i.e. as an antioxidant. Besides phytic acid, legume also contains the compounds of phenol and vitamin E that have antioxidant activity. The aims of this research were to determine the contents of phytic acid and antioxidant activity, and to determine the effect of 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 by 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). The results of this research showed the phytic acid content of velvet bean, butter bean and jack bean from the treatment of P0, P1, P2, P3 and P4 were degraded. The phytic acid of velvet bean of P0, P1, P2, P3 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). Antioxidant activity showed the increase 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. The conclusion that could be taken away from this research were heating techniques had an effect on the degradation of phytic acid at all kind of bean used, and also had an effect on the antioxidant activity at velvet bean and jack bean.