Metabolite profile of whole grain ting (a Southern African fermented product) obtained using two strains of Lactobacillus fermentum

Ting is a traditional fermented sorghum product mostly eaten in Southern Africa, generally believed to be highly nutritious and rich in health beneficial properties. Although refined grains are mostly used for fermented foods, the use of whole grains (WGs) in fermented products is gradually gaining prominence due to their benefits. In this study, Lactobacillus fermentum strains were used singly and in combination for the fermentation of WG-ting from WG-sorghum and all possible metabolites profiled using gas chromatography-high resolution time of flight-mass spectrometry. 198 compounds were observed in the experimented samples, classified into different metabolic groups, with varying proportions: esters (23%), ketones (10%), fatty acids methyl esters (7%), and hydrocarbons (6%). Other important metabolites include vitamins, terpenes and terpenoids, phytosterols, phenols, and alcohols. Although similar lactic acid bacteria were used, differences were observed in levels of the metabolites and in some instances, the types of metabolites obtained differ. Much of the differences were attributed to varying fermentation behaviours of the strains, which could be related to their inherent genes. The correlation between metabolites from raw sorghum and the fermented product may assist in developing processing methods to retain the desired metabolites and enhance their functional potentials toward product improvement and for health benefits.