Vol. 16(20), pp. 1186-1191, 17 May, 2017 DOI: 10.5897/AJB2016.15657 Article Number: AA1CC3164301 ISSN 1684-5315 Copyright © 2017 Author(s) retain the copyright of this article http://www.academicjournals.org/AJB African Journal of Biotechnology Full Length Research Paper Effect of cooking on tannin and phytate content in different bean (Phaseolus vulgaris) varieties grown in Tanzania Mamiro, P. S. 1* , Mwanri, A. W. 1 , Mongi, R. J. 1 , Chivaghula, T. J. 1 , Nyagaya, M. 2 and Ntwenya, J. 3 1 Department of Food Technology, Nutrition and Consumer Sciences, Sokoine University of Agriculture, P. O. Box 3006, Morogoro, Tanzania. 2 The Children's Investment Fund Foundation (UK), 3 rd floor, ABC Place, Waiyaki Way, P. O. Box 1694-00606, Nairobi, Kenya. 3 Department of Public Health, School of Nursing and Public Health, College of Health Sciences, University of Dodoma, P. O. Box 259 Dodoma, Tanzania. Received 8 September, 2016; Accepted 26 April, 2017 Phytates and tannins are present in varying proportions in legume based foods. Investigation on the effect of cooking on tannins and phytates was carried out on thirty eight raw and cooked bean (Phaseolus vulgaris) varieties. Tannins were assayed by vanillin-hydrochloric acid method, while phytates were determined by a method developed by Haugh and Lantzsch. There was a very high significant difference (P≤0.00001) in the tannin concentrations between the raw and cooked bean samples. The mean tannin content for the raw and cooked samples was 1.168±0.81 and 0.563±0.503%CE, respectively. Reduction of tannins after cooking ranged from 20%CE in M’mafutala to 81%CE in GLP 2 with an average reduction of 56.3%CE. Equally, there was a very high significant difference (P≤0.0001) in the phytate concentrations between the raw and cooked bean samples. The mean phytate content for the raw and cooked samples were 0.0219±002 and 0.0122±003 μg/mL, respectively. Cooking reduced the anti-nutritional factors significantly (p≤0.0001). The extent of anti- nutritional factors reduction varied between bean varieties. Cooking is therefore important for mineral absorption during digestion process in humans as it makes the minerals less bound and hence physiologically available. Key words: Beans, phytates, tannins, minerals, raw, cooking, bioavailability. INTRODUCTION The food that has been eaten and swallowed is mixed with saliva, gastric fluids and churned by peristaltic movements of the stomach into a creamy fluid called the chyme. The chyme is an extremely complex matrix, in *Corresponding author. E-mail: petermamiro@suanet.ac.tz or petermamiro@yahoo.com. Author(s) agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License