DEHULLING EFFECT ON THE MICROBIAL POPULATION OF SPONTANEOUSLY FERMENTED SORREL SEED AND STARTER CULTURE DEVELOPMENT FOR SELECTIVE FERMENTATION

Abstract

This research focused on isolating, characterizing and identification of organisms associated with the spontaneous fermentation of dehulled and undehulled sorrel seed (Hibiscus. Sabdariffa L); as well as assessing the fermenting abilities of the isolates for starter culture development. Sorrel seed was dehulled and fermented spontaneously using solid substrate fermentation process for 96h at 25oC ± 2. The undehulled seed was also processed and fermented simultaneously under the same conditions. Samples were taken at 24 h intervals and evaluated for physical properties such as pH, TTA, colour and textural changes. Also microorganisms associated with the fermentation were isolated and characterized using colonial and morphological tests and analytical profile index (API kit). Subsequently some of the microorganisms identified were used for selective fermentation as single and mixed cultures to ascertain their suitability as starter cultures. A total of 23 organisms were identified. The bacteria isolated are Bacillus spp (39.11%), followed by yeasts (21.72%), Latobacillus spp (13.04%), Pediococcus spp (8.69%), Corynebacterium spp (8.69%), Micrococcus spp (4.33%) and Staphylococcus spp (4.33%). Bacillus subtillis was predominant in the fermentation process having 39.11% occurrences. Four (4) species of bacteria and one yeast out of 23 isolates were chosen for starter culture screening. They were Bacillus subtillis, Bacillus licheniformis, Lactobacillus brevis,Lactobacillus plantarum and Saccharomyces cerevisiae. Undehulled sample showed alkaline pH (about 8.30 for the most alkaline) while for dehulled the pH was about7.10. Sorrel selectively fermented with mixed cultures ofBacillus subtillis and Lactobacillus brevis gave the best starter combination because of the desirable physical attributes in terms of odour, texture and colour during the period of fermentation, as such are being proposed as the most suitable starters for sorrel seed fermentation.