The biodiversity of predominant lactic acid bacteria in dolo and pito wort for the production of sorghum beer

Abstract

Aim: To quantify and identify the predominant lactic acid bacteria (LAB) in dolo and pito wort processing, and to examine their biodiversity at strain level. Materials and Results:The processing of dolo and pito wort was studied at four production sites in Burkina Faso and Ghana. The succession of dominant micro-organisms, pH and titratable acidity were determined from sorghum malt through mashing and acidification to final wort. In the sorghum malt and during mashing, the LAB counts were 5AE7-7AE5 log CFU g )1 . Similar levels of yeasts and gram-negative, catalase-positive bacteria were observed. These levels decreased to 3AE7-4AE5 log CFU g )1 and £2-3 log CFU g )1 , respectively, at the end of mashing, including a mild heat treatment. During acidification at ambient temperature (30-33°C) lasting for 12-16 h, LAB counts increased to 8AE8-9AE9 log CFU g )1 , pH decreased from 5AE55 ± 0AE12 to 3AE72 ± 0AE24, and the titratable acidity calculated as lactic acid, increased from 0AE13% to 0AE61%. The gram-negative, catalase-positive bacteria and yeasts observed in the malt and during mashing were no longer detected. A total of 556 strains of LAB were isolated and purified. The LAB isolates were characterized and identified by a polyphasic approach based on phenotypic and genotypic methods, such as carbohydrate fermentation patterns using API 50 CHL, intergenic transcribed spacers-polymerase chain reaction ⁄ restriction fragment length polymorphism (ITS-PCR ⁄ RFLP), pulsed-field gel electrophoresis (PFGE) and 16S rRNA gene sequencing. Lactobacillus fermentum was identified as the dominant LAB species in the malt during mashing and during acidification. The other species observed during acidification were Lactobacillus delbrueckii ssp. delbrueckii, Lact. delbrueckii ssp. bulgaricus and Pediococcus acidilactici. These bacteria comprised a minor fraction of the bacterial population and no distinct microbial succession was observed for the LAB. At species level, the LAB profiles were similar for the four production sites; however, a pronounced diversity was observed at strain level. For one site, which had implemented a cleaning procedure between batches only, Lact. fermentum was found. Conclusion: Lact. fermentum was found to be the dominant LAB species throughout the entire process to final dolo and pito wort, including the acidification. Lact. delbrueckii ssp. delbrueckii, Lact. delbrueckii ssp. bulgaricus and P. acidilactici occurred in low numbers. At strain level, a high diversity based on PFGE-RFLP was observed for Lact. fermentum within and between sites.

Influence of Freeze-Dried Yeast Starter Cultures on Volatile Compounds of Tchapalo, a Traditional Sorghum Beer from Côte d’Ivoire

“…In this context, there is a growing demand for new and improved sorghum beer yeast strains to obtain beers with constant organoleptic characteristics. This demand could be met by non-Saccharomyces sorghum beer yeasts, which are described as fermentations improvers and producers of concentrations of fermentation metabolites of brewing importance [4,7,15,16]. A wide range of volatile compounds was detected in the sorghum beer samples, including six esters, four higher alcohols, six acids and one fatty acid (Figure 2).…”

“…Various investigations on the use of starter culture for sorghum beer production have been done [15][16][17][18]. Beers obtained from inoculation tests with these starters showed organoleptic and sensory characteristics comparable to beers produced in the traditional way.…”

Microbiological Quality of a Locally Brewed Alcoholic Beverage (Pito) Sold in a Community within the Greater Accra Region, Ghana

“…Apart from Saccharomyces cerevisiae, the bacterial isolates from the pito samples can be considered microbial contaminants even though the quantities were within the acceptable limits. In a similar study, lactic acid bacteria isolates were found to be involved in the various production stages of Pito [29]. Staphylococcus aureus is a normal flora of the skin, and the common ethological agent of septic arthritis [30].…”

Effect of the fermentation on the microbial population occurring during the processing of zoom-koom, a traditional beverage in Burkina Faso

“…For solid samples, 10 g of product were mixed with 20 ml of distilled water prior to pH measurement. For liquid samples, the pH was measured directly (Sawadogo-Lingani et al, 2007). The temperature at the beginning and at the end of fermentation was measured with a thermometer (Rweger V104, Swiss).…”

“…The microbiota of many African traditional fermented cereal products have been investigated, e.g. maize based products like kenkey (Halm et al, 1993;Olasupo et al, 1997;Hayford et al, 1999), mawè (Hounhouigan et al, 1993a(Hounhouigan et al, ,b, 1994 and ogi (Johansson et al, 1995;Olasupo et al, 1997), sorghum based product like kisra (Hamad et al, 1992) and dolo (Sawadogo-Lingani et al, 2007), millet based products like kunu-zaki (Olasupo et al, 1997) and bensaalga (Tou et al, 2006). However, only a few studies have been done to date on zoom-koom (Barro et al, 2007;Soma, 2014) and its fermentation process and no information is available on the kinds of micro-organisms involved in the spontaneous fermentation of the dough.…”