Effect Of Fermentation And Cooking On Proximate Composition And Protein Quality Of The Flour Of Tow Maize (Zea Mays Linnaus) Cultivars

Abstract

Maize like other cereals shows qualitative and quantitative deficiency in protein content. Efforts were made to correct this by fortification, supplementation and fermentation. Fermentation as additional value by improving organoleptic qualities of cereal food products. Fermentation is accompanied by drop in pH. This is advantageous in handling foods under poor sanitary practices which resulting inhibition pathogenic microorganisms. The objective of this study is to determine the effect of fermentation followed by cooking on the nutritional quality of corn foods product. Maize flour of two cultivars namely: Hudeiba I and Mugtama 45 were fermented naturally for 36h. Samples were taken at 4h interval, dried and kept for further analysis. The pH drop was from 5.7 to 3.8 at the end of fermentation. The protein content increased significantly (P<0.05) for Hudeiba 1 from 12.2 to 13.2% for 8h fermentation, while for Mugtama 45 it increased significantly (P<0.05) from 11.5 to 12.7% for 24h and 28h fermentation. The in vitro protein digestibility was enhanced by fermentation to a level of 18.6% for Hudeiba 1 and 19.5% for Mugtama 45 after 20h fermentation for both. viii Fermentation induced a significant improvement in protein fraction by causing significant increase in globulin plus albumin for Hudeiba1 (19.4%) and for Mugtama 45 (20.9%). The amino acids composition of corn is characterized by low lysine and tryptophan content. Samples with high globulin plus albumin were of better quality in relation to lysine content. The lysine content was improved from 1.8 to 2.3 g/100g protein for Hudeiba 1 and 1.9 to 2.6 g/100g protein for Mugtama 45. Cooking of fermented samples increased the protein content from 13.0 to 13.4% for Hudeiba 1 and from 12.6 to 14.1% for Mugtama 45. Cooking also resulted in a significant (P<0.05) loss in globulin plus albumin. The essential amino acids decreased when dough was cooked. The in vitro protein digestibility of cooked sample decreased significantly (P<0.05) however, the negative effects of cooking were lower than those of unfermented cooked samples.