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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.

Aims: To determine the profile of volatile compounds responsible for the aroma of Soumbala produced spontaneously and with pure and mixed cultures of Bacillus subtilis and Bacillus pumilus. Methods and Results: Traditional and controlled fermentation trials of African locust bean with pure and mixed starter cultures of B. subtilis (B7, B9 and B15) and B. pumilus (B10) were performed. Aroma volatiles were analysed using Likens-Nikerson method coupled with gas chromatography and mass spectrophotometry. Sensory analysis of Soumbala as well as rice dishes prepared with each type of Soumbala were carried out by 10 panellists. In total 116 compounds were identified. They included pyrazines, aldehydes, ketones, esters, alcohols, acids, alkanes, alkenes, amines, pyridines, benzenes, phenols, sulphurs, furans and other compounds. Using principal component analysis for comparison, the aroma profiles of the Soumbala samples could be separated into three groups. The sensory evaluation showed variable acceptability. However, it was noticed that Soumbala samples produced with starter cultures were scored higher than traditionally prepared Soumbala. Conclusions: Aroma volatiles and organoleptic properties of Soumbala vary according to the Bacillus isolates involved in the fermentation. Significance and Impact of the Study: This study contributes to the selection of Bacillus starter cultures for controlled production of Soumbala.

Volatile compounds in afitin, iru and sonru, three traditional food condiments produced in Benin by natural fermentation of the African locust bean (Parkia biglobosa) were identified and quantified, using the LikensNickerson simultaneous distillation-extraction method and GC-MS analysis. A total of 13 chemical groups of volatile compounds were identified and classified in six major groups: pyrazines, aldehydes, ketones, alcohols, esters and benzene derivatives. From these groups, 2,5-dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal, 2-decanone, 3,5-dimethylphenylmethanol, ethyl linoleate and chlorobenzene were found in higher amounts in the three condiments. Afitin was characterized by high concentration of 2-decanone, whereas 2,5-dimethylpyrazine, tetramethylpyrazine, 3-methylbutanal and ethyl linoleate were found particularly in higher concentration, both in iru and sonru.