Evaluation and Optimization of the Cassava Production Processes

INTRODUCTION

Cassava (Manihot esculenta) is an important food in the tropical areas of African, Asia and Latin America. It is estimated (IITA, 1990) that the crop provides about 40% of all the calories consumed in Africa and ranks second only to cereal grains as chief source of energy in Nigerian diet (Ngoddy, 1989). By this, cassava plays important role in alleviating African Food Crisis though poor in protein (1.20%) and rich in cyanide (10 mg/100g fresh weight) in some varieties such as TMS 50395 (IITA, 1990; Janssens, 2001). The variety/clone NR8082 is low cyanide high-yielding cassava developed by the National Root Crops Research Institute, Nigeria and commonly distributed to Nigerian farmers.

Raw cassava has been reported (Onabolu, 1989; Cereda and Mattos, 1996) to contain two cyanogenic glycosides known as linamarin and lotaustralin with the former being the most representative glucoside, accounting for about 80% of the total cassava glucoside (Dicar, 1993). Linamarin and lotaustralin are -glucosides of acetone cyanohydrin and ethyl-methyl-ketone-cyanohydrin, respectively (Cereda and Mattos, 1996). Linamarin produces the toxic compound (hydrogen cyanide, HCN), which can be hazardous to the consumer. Cassava processing by fermentation is one of the most widespread techniques used in Africa and is considered an efficient means of reducing cyanogenic potential in the resulting food (Brainbridge, 1994). Lafun is fermented cassava flour popular among the people in the Southwestern States of Nigeria (Cereda and Mattos, 1996). The traditional method of processing cassava into lafun though unique for its ability to reduce the toxic cyanogenic compound to a least possible level (Numfor, 1983) imparts a strong smell to the product (Cereda and Mattos, 1996). Lafun, like gari, another fermented product from cassava, is a dry product, which can be preserved for a long time under the prevailing local environment. It is a cheap and popular meal in the rural areas of Nigeria and can be prepared into ready food much more quickly than garri (Latunde-Dada, 1997). Lafun is generally prepared into a thick paste in boiling water and eaten with vegetable soup or stew. Oyewole and Ogundele (2001) reported that lafun quality varies with processing methods and with processors. In spite of various reports in literature (Oyewole and Odunfa, 1990; Oyewole and Afolami, 2000; Oyewole and Ogundele, 2001) on lafun production from different cassava varieties, there is scarcity of information on efforts to optimize known process conditions for maximum product quality in mind. The need to optimize process conditions to enhance product quality in terms of yield, cyanogenic potentials and sensory acceptability through response surface methodology, becomes relevant given the present need for small scale food processing and spread of consumers.