Microbiological and chemical characterisation of ting, a sorghum-based sourdough product from Botswana

Ting is a fermented sorghum product of Botswana which is used to prepare porridges of different consistencies. This study aimed to characterise ting with respect to fermentation microbiota and metabolite composition, and to develop starter cultures for ting fermentation. The pH values of 10 ting samples from Botswana ranged between 3.5 and 4.0 and cell counts ranged between 1.2 × 108 and 1.2 × 1010 cfu/g lactic acid bacteria. Yeast cell counts were below 105 cfu/g in all samples and Enterobacteriaceae were less than 10 cfu/g. The microbiota of samples consisted of 2–4 dominant strains and strains were identified based on the sequence of their 16S rRNA genes as Lactobacillus reuteri, Lactobacillus fermentum, Lactobacillus harbinensis, Lactobacillus plantarum, Lactobacillus parabuchneri, Lactobacillus casei and Lactobacillus coryniformis.Binary strain combinations were employed as starter cultures to produce ting. Major fermentation products were lactate, acetate and ethanol, additionally, 1,2 propanediol and 1,3 propanediol were produced by some strains. All strains were capable of producing ting, which was accompanied by a decrease in pH from 6.3 to 4 within 8 h. Traditionally processed ting requires 2 to 3 days to attain a pH below 4; the starter cultures thus reduced the fermentation time to 8 h.

► The study established that the microflora of ting, a sorghum sourdough produced in Botswana.
► Ting microbiota of 10 samples consisted of 2–4 dominant strains of lactobacilli.
► Isolates were suitable as binary starter cultures to produce ting.
► The metabolites 1,2 propanediol and 1,3 propanediol were produced by some strains in situ.
► Selected isolates were selected to produce air-dried starter cultures.