Evaluation of selected lactic acid bacteria as starter cultures for gluten-free sourdough bread production

O. Parakhina, M. Lokachuk, L. Kuznetsova, O. Savkina*, E. Pavlovskaya and T. Gavrilova

St. Petersburg branch Scientific Research Institute for the Baking Industry, Podbelskogo highway 7, RU196608 St. Petersburg, Pushkin, Russian Federation
*Correspondence: 1103savkina@mail.ru

Abstract:

Sourdough is one of the most promising technologies for gluten-free bread. The selection of appropriate starter cultures for the production of gluten-free sourdoughs is of a great importance, since not all microorganisms can adapt equally to the same raw material. The aim was to create a new starter microbial composition for gluten-free sourdough preparation, allowing improving the quality and the microbiological safety of gluten-free bread. Screening was conducted on 8 strains of lactic acid bacteria (LAB) and 5 strains of yeast previously isolated from spontaneously fermenting rice and buckwheat sourdoughs. The strain S. cerevisiae Y205 had the highest fermentative activity and alcohols content. The lactic acid bacteria L. brevis E139 and L. plantarum Е138 were also experimentally selected for new gluten-free sourdoughs on the basis of acidity and volatile acids production and antagonistic activity. Two types of microbial composition were created and its influence on sourdough biotechnological indicators was studied. Sourdough with L. plantarum Е138 had in 1.2 times lower titratable acidity, in 3.4 times lower volatile acids content compared to sourdough with L. brevis E139. Alcohol content was the same in both sourdoughs similarly to yeast cells amount. Sourdough dough proofing time increased in 1.2–1.3 times compared to the control. Sourdough did not affect the specific volume, porosity and compressibility of gluten-free bread, but its sensory characteristics were improved. Bread made with sourdoughs had more pronounced taste and flavor, brighter crust color and better texture compared bread without sourdough. The microbiological safety of sourdough gluten-free bread was also increased, especially when L. brevis E139 was used.

Key words:

Identification of yeast species involved in fermentation of the Kazakh camel dairy product–shubat

L. Nadtochii¹*, A. Orazov¹*, L. Kuznetsova², A. Pinaev³, L. Weihong⁴, S. Garbuz¹ and M. Muradova¹

¹ITMO University, Department of Applied Biotechnology, Lomonosov street 9, RU191002 Saint Petersburg, Russian Federation
²The Russian Academy of Agricultural Sciences, The Saint Petersburg Branch State Research Institute of a Baking Industry, Podbelsky Chaussee 7, RU196608 Saint Petersburg, Pushkin, Russian Federation
³All-Russia Research Institute for Agriculture Microbiology, Laboratory of Genetics of Plant-Microbe Interactions, Podbelsky Chaussee 3, RU196608 Saint Petersburg, Pushkin, Russian Federation
⁴Harbin Institute of Technology, Institute of Food Science and Engineering, School of Chemistry Engineering, Xidazhi street 92, CN150001, Harbin, Heilongjiang, P.R. China
*Correspondence: l_tochka@corp.ifmo.ru, orazov@corp.ifmo.ru

Abstract:

In certain countries of the world, camel’s milk is used for food on a level with cow’s milk. Shubat is a traditional food product based on camel milk in Kazakhstan. It is a fermented milk product obtained as a result of spontaneous fermentation of camel’s milk under the influence of native microflora. Received dairy product from the southern region of Kazakhstan became the object of the investigation of the microflora of the fermented milk product shubat. The aim of the research was to study the microflora of camel milk, which causes its spontaneous fermentation. During the experiment, the dynamics of acid accumulation by the change in active acidity (pH) and titratable acidity (°T) was studied. In addition to lactic fermentation fermented product (shubat), alcoholic fermentation was noted, which has given the finished product an increased acidity and a high degree of gassing. To enumerate and identify microorganisms, shubat was sown to the following nutrient media: MRS, Malt wort-agar medium at 36 °C and 30 °C respectively both for 3 days. We suppose that the dominant component of the shubat’s microflora was yeasts: Brettanomyces anomalus, Naumovozyma castellii. Pathogenic microorganisms, such as Salmonella, Shigella, were not detected during the research, considering that the shubat is formed as a result of spontaneous fermentation and has poor hygienic characteristics in comparison with pasteurized milk. Identification of individual strains of bacteria allows us to simulate a starter microflora for the production of a safe fermented product based on camel milk on an industrial scale in Kazakhstan. The identified microflora, which causes spontaneous fermentation of camel milk and isolated strains of lactic acid bacteria, will make a significant contribution to the improvement of food safety in arid regions.

Key words:

Brettanomyces anomalus, camel milk, lactic acid bacteria, Naumovozyma castellii, shubat, spontaneously fermented dairy products, yeasts