Isolation of exopolysaccharide-producing yeast and lactic acid bacteria from quinoa (Chenopodium quinoa) sourdough fermentation

Authors: FRANCO, WENDY - University Of Catolica De Chile; Perez Diaz, Ilenys; CONNELLY, LAUREN - North Carolina State University; DIAZ, JOSCELIN - University Of Catolica De Chile

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2020
Publication Date: 3/13/2020
Citation: Franco, W., Perez Diaz, I.M., Connelly, L.E., Diaz, J. 2020. Isolation of exopolysaccharide-producing yeast and lactic acid bacteria from quinoa (Chenopodium quinoa) sourdough fermentation. Foods. 9(3):337. https://doi.org/10.3390/foods9030337.
DOI: https://doi.org/10.3390/foods9030337

Interpretive Summary: Originally form the Andes; quinoa is a seed crop rich in proteins, lipids, fiber, vitamins and minerals. Its protein content (approximately 14%) is superior to wheat and other cereals and it is characterized for its excellent balance of essential amino acids. In addition, quinoa has been found to contain saponins, phytosterols, phytoecdysteroids, phenolics and bioactive peptides, omega 3 acids and antioxidants. Although, the use of quinoa provides the celiac and non-celiac individuals with an alternative product that could balance the nutritional factors associated with the deficiencies of any diet, including gluten-free diets, its use in bread making has been limited because of its low baking quality and the compromised sensory quality of the resulting gluten free bread. An alternative to overcome these problems is to use microbial fermentation as part of bread making. The sourdough technology has been successfully used to improve flavor and texture of rye, wheat, oat, and sorghum bread, and can be applied to the quinoa flour as well. Quinoa flour as substrate for fermentations represents an ideal medium for the growth of fermentative and potentially probiotic lactic acid bacteria and yeasts. This study characterized the spontaneous fermentation of quinoa flour to produce 100% quinoa bread sourdough. It was determined that while a variety of lactic acid bacteria prevail in spontaneous fermentation of quinoa flours, the incorporation of a starter culture is needed to enhanced the early exclusion of microbes of public health significance in the sourdough. Future studies are to determine if the modified fermentation is to yield a sourdough that is successfully converted into quinoa bread.

Technical Abstract: Quinoa, a nutritional grain, can be used as an ingredient in gluten-free sourdoughs. This study characterizes quinoa flour spontaneous fermentation with emphasis in the isolation of exopolysaccharide (EPS) producer bacteria. Real, red and black grains were studied. Dough yield, microbiota composition and fermentation biochemistry were determined for a total of 36 quinoa flour fermentations. The fermentation biochemistry was monitored by high-performance liquid chromatography (HPLC) analysis, pH measurement and titratable acidity. Changes in the microbiota were monitored by plating on deMann Rogosa and Sharp 5 agar (MRS5) and yeast and mold agar (YMA) plates and with metagenetic analysis. The ability to produce exopolysaccharides was screened in selected lactic acid bacteria (LAB) isolates. Production of organic acids in the spontaneous fermentation dropped the pH to 4.0 ± 0.3. The community of presumptive LAB reached 8.37 ± 0.01 log colony forming units (CFU)/mL by day 8 of back-slopped fermentations. The microbiota was composed of Lactobacillus, Enterococcus, Leuconostoc, Lactococcus, Pediococcus and Weissella. P. pentosaceous, L. citreum and W. cibaria were able to produce EPS in a starch-rich medium. P. pentosaceous showed higher exopolysaccharide yield, rapid acidifying kinetics and was able to drop the dough broth pH to values below 4.0 and a positive fermentation quotient after 24 h of incubation. Therefore, the bacterium might be a potential candidate for quinoa sourdough production.