Characterization of the microbiota and volatile components of kocho, a traditional fermented food of Ethiopia.

Kocho is a traditional product in Ethiopia, prepared by fermenting parts of 'false banana' plants (Ensete ventricosum). Fermentation practices of kocho vary depending on the region of Ethiopia. In this study, 14 kocho samples originating from four different areas were investigated. They varied both in the fermentation technique and the duration of fermentation. Samples were analysed to determine the microbial community using culture-independent 16S amplicon high-throughput sequencing. In addition, bacterial strains were isolated and identified. Furthermore, the volatile profiles were characterized by HS-SPME treatment coupled with GC/MS. The results indicated that Lactobacillus and Acetobacter were the most dominant genera during kocho fermentation with Lactobacillus plantarum and Lactobacillus brevis being the prevalent species of Lactobacillus. The analysis of the volatile profiles demonstrated that acetic acid and butanoic acid prevailed in all samples. Our results showed that kocho samples prepared in different areas and using different processing methods varied both in the composition of the microbiota and in their volatile profiles.

Antinutritional factors and in vitro protein digestibility of improved haricot bean (Phaseolus vulgaris L.) varieties grown in Ethiopia.

The antinutrient (raffinose oligosaccharides, tannins, phytic acid and trypsin inhibitors) composition and in vitro protein digestibility of eight improved varieties of Phaseolus vulgaris grown in Ethiopia were determined. Stachyose was the predominant alpha-galactosides in all haricot bean samples. Raffinose was also present in significant quantities but verbascose, glucose and fructose were not detected at all in the samples. The concentrations observed for the protein digestibility and antinutritional factors, varied significantly (P<0.05) between varieties investigated in this study. Mean values for protein digestibility ranged from 80.66% (in Roba variety) to 65.64% (in Beshbesh variety). Mean values for raffinose, stachyose, sucrose, trypsin inhibitors, tannins and phytic acid were 3.14 mg/g, 14.86 mg/g, 24.22 mg/g, 20.68 TUIx10(3)/g, 17.44 mg, catechin equivalents/g and 20.54 mg/g respectively. Statistical analyses of data revealed that antinutritional factors and protein digestibility were influenced by variety (genotype). Relationships between antinutritional factors and protein digestibility were also observed. The possibility of selecting varieties to be used for large-scale cultivation in Ethiopia on the basis of these data is discussed. Among the improved varieties studied, Roba, Redwolaita, Mexican and Awash were found to be the best food and export type of haricot beans in the Ethiopian context, because of their higher protein digestibility, lower antinutrtional factors and other beneficial nutritional parameters. Roba variety can be used by local food processors for the production of value-added bean-based products especially to combat the problem of protein energy malnutrition and related diseases which are very common in developing countries.