Study of factors affecting the pathogenic microbiota growth on the surface of thermophilic sourdough and development of methods for its inhibition

St.Petersburg branch Scientific Research Institute for the Baking Industry, Podbelskogo highway 7, 196608, St.Petersburg, Pushkin, Russian Federation

^* Corresponding author: 1103savkina@mail.ru

Abstract

Sourdough is an important ingredient in the breadmaking. In the Baltic countries, Belarus, Ukraine and Russia, thermophilic rye sourdough are widely used, which are prepared using saccharified flour scald (scalded flour) and fermented at elevated temperatures (>35 °C). Pure cultures of L. amylolyticus 76 are widely used for thermophilic sourdough preparation. The aim of the research was to identify the causes of the spore-forming bacteria germination and the appearance of an unpleasant odor at the end of the first step of thermophilic sourdough preparation when thermophilic strain L. amylolyticus is used, as well as to develop methods for suppressing the development of unwanted microorganisms. Using the 16S rRNA sequencing method, it was established that the isolated bacteria belong to the species Bacillus licheniformis. Water at a temperature of 58-60 to 77-78 °C and steam inhibit the development of spore-forming bacteria, while water at a temperature above 97°C activates spores. The effect physiological activity of pure cultures L. amylolyticus 76 on the sourdough quality and the undesirable microflora growth was investigated. The influense of anaerobic conditions on the sourdough surface, for example, by creating a protective film of vegetable oil, also as acidifying of sourdough by lactic acid or glacial acetic acid was established.