EFFECTS OF STORAGE ON THE CHEMICAL COMPOSITION AND FOOD QUALITY OF YAM BOLANLE O. OTEGBAYO 1,5 , ROBERT ASIEDU 2,3 and MPOKO BOKANGA 4 1 Bowen University, P.M.B. 284, Iwo, Osun State, Nigeria 2 International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria 3 IITA, Croydon, UK 4 UNIDO, Abuja, Nigeria 5 Corresponding author. TEL: +2348034727399; EMAIL: botegbayo@yahoo.co.uk Received for Publication June 22, 2010 Accepted for Publication June 7, 2011 doi:10.1111/j.1745-4549.2011.00600.x ABSTRACT The effects of storage (4 months) on the chemical composition of yam tubers and its relation to textural quality of a major yam food product (pounded yam) were studied using six varieties of Dioscorea rotundata and D. alata. Chemical composi- tion of both freshly harvested tubers and those stored for 4 months were determined by standard methods of analysis. Sugar, nonstarchy carbohydrate and dry matter contents of the tubers increased during storage while the starch, fat and protein con- tents decreased. Pounded yam made from stored yam tubers were of better textural quality than those from freshly harvested ones. Storage of yam tubers could be an effective way of improving the textural quality of pounded yam. This is important for processing yam tubers into value-added products. PRACTICAL APPLICATION The results of this research provide a scientific basis for differences in the food quality of food products made from freshly harvested and stored yam tubers. Storage is important to the industrial processing of value-added products (e.g., instant yam flour, yam flakes) from yam tubers. This study will help processors in selecting appropriate raw materials that will give optimal food quality that is expected and will be accepted by consumers. INTRODUCTION Yams (Dioscorea spp.) are climbing monocotyledonous vines that produce large underground tubers. They are an integral part of food systems in the tropics, estimated to provide more than 200 dietary calories each day for over 60 million people (FAO 2002).Yams constitute a nutritious, high-carbohydrate and high-fiber food source. They are of major importance in the diet and economic welfare of people in West Africa, the Caribbean islands, Asia and Oceania. Fresh yam tubers are stored to provide seeds for the next planting season, to reduce seasonal glut and to ensure extended availability (Coursey 1967; Ajayi and Madueke 1990). Yam can be processed into many food forms such as fried yam, boiled yam, roasted yam or pounded yam. Pounded yam is glutinous dough processed by pounding and kneading of boiled yam. The ethno-cultural significance of yam tubers still make people prefer that their pounded yam (arguably the most popular traditional food product from yam in West Africa, called Iyan in Nigeria, Foutou in Cote D’ivoire and Fufu in Togo, Benin and Ghana) come from fresh tubers rather than processed instant yam flour (which reduces the drudgery of pounding and knead- ing). Most consumers of pounded yam prefer the textural quality of pounded yam made from stored yam tubers to that made from fresh yam. This makes the stored yam tubers command a higher price in the market than the fresh tubers. Textural quality is the most important food quality attribute of pounded yam. A traditional consumer of pounded yam would want to find out if the feel or touch is acceptable before considering other factors like taste, color, aroma of the food product (Akissoe et al. 2001; Egesi et al. 2003; Otegbayo et al. 2005; Brunnschweiler et al. 2006). The aforementioned reasons therefore made it pertinent to investigate the effect of storage of yam tubers on the textural quality of pounded yam. Journal of Food Processing and Preservation ISSN 1745-4549 1 Journal of Food Processing and Preservation •• (2011) ••–•• © 2011 Wiley Periodicals, Inc.