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Aims: To identify and compare the volatile compounds associated with maize dough samples prepared by spontaneous fermentation and by the use of added starter cultures in Ghana. Methods and Results: The starter cultures examined were Lactobacillus fermentum, Saccharomyces cerevisiae and Candida krusei. For identification of aroma volatiles, extracts by the Likens-Nickerson simultaneous distillation and extraction technique were analysed by gas chromatography-mass spectrometry (GC-MS) and using a trained panel of four judges by GC-Olfactometry (GC-sniffing). Compounds identified by GC-MS in maize dough samples after 72 h of fermentation included 20 alcohols, 22 carbonyls, 11 esters, seven acids, a furan and three phenolic compounds. Of the total 64 volatile compounds, 51 were detected by GC-sniffing as contributing to the aroma of the different fermented dough samples. Spontaneously fermented maize dough was characterized by higher levels of carbonyl compounds while fermentations with added L. fermentum recorded the highest concentration of acetic acid. S. cerevisiae produced higher amounts of fusel alcohols and increasing levels of esters with fermentation time and C. krusei showed similarity to L. fermentum with lower levels of most volatiles identified. Conclusion: The present study has given a detailed picture of the aroma compounds in fermented maize and demonstrated that the predominant micro-organisms in fermented maize dough can be used as starter cultures to modify the aroma of fermented maize dough. Significance and Impact of the Study: The study has documented the advantage of using starter cultures in African traditional food processing and provided a scientific background for introducing better controlled fermentations.

MATERIALS&METHODSA method has been developed to measure the texture of raw and soaked cowpeas (Vigna unguicuiata) using a wedge-type blade mounted in an Instron testing machine to cut across the cotyledons. It was found that soaking raw cowpeas in water prior to cooking produced a softer bean and the decrease in hardness was proportional to the soaking time. Texture of cooked beans could be predicted from the texture of the corresponding soaked bean. The influence of cooking temperature and time on bean texture was studied using the shear-compression cell of -the Texture Test System and the Ottawa Texture Measuring System cell with a wire extrusion grid. It was found that the rate of cooking relative to texture followed first order kinetics. Scanning electron microscopy was used to study changes in microstructure during the cooking process. The major effect observed was a breakdown of the middle lamella; cell walls remained intact.