Fermentation of Seeds of Teff (Eragrostis teff), Grass-pea (Lathyrus sativus), and Their Mixtures: Aspects of Nutrition and Food Safety

Abstract

Fermentation of pure teff (Eragrostis teff), pure grass-pea (Lathyrus sativus), and their mixtures, 9:1 and 8:2 (teff/grass-pea) has been done at two temperatures (room temperature and 35 degrees C) in duplicate using the strains of Lactobacillus plantarum, for bacterial fermentation, and Aspergillus oryzae and Rhizopus oligosporus in succession for solid-state fungal fermentation as inocula. In addition, the natural or spontaneous and back-slopping methods of bacterial fermentation have been done on the above four substrate groups. The pH and essential amino acid profiles of the different fermentation processes were compared. The back-slopping in teff at a temperature of 35 degrees C gave the sharpest pH drop. All fermentations done at 35 degrees C showed a steeper slope in their pH versus time plot compared to their room temperature counterpart. Fungal fermentation gave an improved amino acid profile for the essential ones in all of the substrate groups, except in pure grass-pea. Fermented teff/grass-pea (8:2) in this fungal fermentation has been found to be quite comparable in essential amino acid profile to an ideal reference protein recommended for children of 2-5 years of age. None of the bacterial fermentations produced a net change in their essential amino acid profile in any of the substrate groups investigated. Solid state fungal fermentation on pure grass-pea using the fungal strains R. oligosporous and A. oryzae in succession has shown that the neurotoxin beta-N-oxalyl-alpha,beta-diaminopropionic acid (beta-ODAP) in grass-pea has been removed by 80% on average for the high-toxin variety and by up to 97% for the low-toxin variety as determined by an improved chromatographic method with bioelectrochemical detection coupled on-line with refractive index detection.