In-vitro Analysis of Trypsin and Alpha - Amylase Inhibitory Activities in Selected Legume Varieties in Sri Lanka
A. M. C. N. Abeykoon
Department of Food Science and Technology, Faculty of Applied Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka.
H. M. T. Herath *
Food Technology Section (FTS), Modern Research and Development Complex, Industrial Technology Institute (ITI), 503A, Halbarawa Gardens, Malabe, Sri Lanka.
M. A. Jayasinghe
Department of Food Science and Technology, Faculty of Applied Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka.
*Author to whom correspondence should be addressed.
Abstract
Aim: To quantify the Trypsin Inhibitory Activity (TIA) and Alpha - Amylase Inhibitory Activity (AIA) in legume varieties with effect of cooking.
Study Design: Seeds of twelve legume varieties grown in Complete Randomized Block Design (CRBD) in experimental field conditions were used and data analysis was performed using one-way ANOVA at 95% confidence interval using MINITAB statistical software.
Place and Duration of Study: Grain Legumes and Oil Crops Research and Development Centre (GLOCRDC), Angunakolapalessa and Industrial Technology Institute (ITI), Colombo, Sri Lanka between June 2019 and Dec 2019.
Methods: Ethanolic (80%) extracts of raw and cooked grain legumes were used. In determining TIA, N-α-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPA) is used as a synthetic substrate for trypsin enzyme and the rate of hydrolysis was measured by intensity of colour released by p-nitroaniline. AIA was carried out determining the maltose content which was released by hydrolysis of starch in the presence of amylase enzyme using reduction of 3, 5-dinitrosalicylic acid.
Results: TIA in raw legumes ranged from 0.65±0.02 mg/g (ANK- Brown) to 1.52±0.01 mg/g (ANKCP1) while in cooked legumes ranged from -0.11±0.1 mg/g (ANK-Black) to 0.61±0.02 mg/g (MI 5). In pressure cooking (120oC, 10 min) considerable reduction in TIA of 53.74% (MI6) to 100% (ANK-Black, Bombay) was observed. A significant difference (p<0.05) in TIA among the varieties as well as among cooked form of varieties were observed (one- way ANOVA). Further a significant difference (p<0.05) in TIA was observed between cooked and raw form in each legume variety (Paired T-Test).
AIA of cooked samples was ranged from - 11.61% (MI 6) - 23.05% (MISB1) and there was no significant difference (p<0.05) in AIA among the most of the legume varieties.
Conclusion: A significant reduction of TIA among the legumes varieties was observed in the pressure cooking process while a significant activity of alpha- amylase was not seen in cooked legumes.
Keywords: Leguminosae, anti-nutritional factors, pressure cooking, protease inhibitors, starch blockers.