Impact of using the developed starter culture on the quality of sourdough, dough and wheat bread

O. Savkina¹*, L. Kuznetsova², O. Parakhina¹, M. Lokachuk¹ and E. Pavlovskaya¹

¹ St. Petersburg branch State Research Institute of Baking Industry, Podbelskogo highway 7, RU196608, St. Petersburg, Pushkin, Russia
² Institute of Refrigeration and Biotechnologies, ITMO University, Lomonosova street, 9, RU191002, St. Petersburg, Russia
*Correspondence: 1103savkina@mail.ru

Abstract:

There is no technological necessity of sourdough usage when preparing wheat bread as it can be prepared without sourdough but only with yeast using. However, sourdough helps to solve such problems as fast microbial spoilage, unexpressed taste and smell, crumbling crumb. The use of sourdough prepared with directional cultivation of microorganisms allows to produce high-quality competitive bread. Developing a starter culture with an optimized microbial composition was the purpose of this study, allowing the quality and the microbiological stability of wheat bread improving. A new starter microbial composition for the sourdough was developed. Lactic acid bacteria strains L. plantarum Е90, L. brevis Е120 and yeast S. cerevisiae Y139 were selected for the new composition. It was proven that the rice products using to microorganism immobilization allows saving the largest number of living cells after drying and during storage. The rate of acid accumulation in sourdough was established. The sourdough dynamic viscosity decrease at the end of fermentation by 2.2 times was established, which means that the fermentation process leads to the sourdough liquefactio. The optimal dosage was established (5–10% flour in sourdough). This dosage provided good physico-chemical and organoleptic quality indicators of bread. It was proved that the sourdough usage allows getting good-quality bread even when the flour with unsatisfactory amylolytic activity (high drop number) is used. Slowing down the microbial spoilage in sourdough bread was proven. In general, the developed sourdough wheat bread biotechnology improves bread quality and its resistance to the ropy-bread disease.

Key words:

lactic fermentation, microbial spoilage, sourdough bread, wheat sourdough, yeast

A study of factors which influence mould spoilage in flat (sourdough) bread

L. Kuznetsova & O. Savkina*

Institute of Refrigeration and Biotechnologies, ITMO University, Lomonosova Street 9, 191002 St Petersburg, Russia;
*Correspondence: 1103savkina@mail.ru

Abstract:

Bakery products are an excellent substrate for the development of microbial spoilage, especially mould spoilage and lime disease (otherwise known as chalk disease), because they have high levels of water activity aw = 0.94-0.97 and pH 5.5-6.0. Sliced bread in its packaging is highly susceptible to moulds and lime disease during storage. The aim of this study was to investigate the effects shown by the microbial contamination of flour quality, and the type of sourdough and organic acid, especially acetic acid, on mould spoilage in wheat and rye wheat bread. Microbial contaminations were studied in two batches of wheat flour and three batches of rye flour which had been manufactured in Belarus and Russia and in sourdough bread which had been produced using this flour. Investigated here was the impact of the quality and type of sourdough with various starter cultures of micro-organisms and the impact of the content of organic acid, especially acetic acid, on mould spoilage in wheat and rye wheat bread. The content of organic acids, including acetic acid, in different types of sourdough which has been prepared using different starter cultures and in different kinds of sourdough bread which have been studied using liquid chromatography. It was found that, in spite of the presence in flour of spore-forming bacteria, yeasts, and fungi, microbial contamination of the finished product immediately after baking was absent. It was proven that the use of starter cultures and sourdough can slow down or prevent entirely the microbial spoilage of bread. It was found that the content of acetic acid which had been accumulated during the fermentation of various types of sourdough served to effect the presence of mould spoilage on sourdough bread.

Key words: