Tag Archives: yeast

625-636 D. Manshin, T.V. Meledina, T. Britvina, S.G. Davydenko, N.V. Shelekhova, V. Andreev and A. Andreeva
Comparison of the yeast Saccharomyces cerevisiae var. boulardii and top-fermenting brewing yeast strains during the fermentation of model nutrient media and beer wort
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Comparison of the yeast Saccharomyces cerevisiae var. boulardii and top-fermenting brewing yeast strains during the fermentation of model nutrient media and beer wort

D. Manshin¹*, T.V. Meledina¹, T. Britvina¹, S.G. Davydenko², N.V. Shelekhova³, V. Andreev² and A. Andreeva¹

¹ITMO University, Faculty of Biotechnologies (BioTech), Lomonosov street 9, RU191002 Saint-Petersburg, Russia
²Innovation & Research Department, Baltika Breweries, 6-th Verkhnij ln. 3, RU194292 St. Petersburg, Russia
³Russian Research Institute of Food Biotechnology, Department of Biotechnology and Food Safety, Samokatnaya street 4b, RU111033 Moscow, Russia
*Correspondence: dvmanshin@itmo.ru

Abstract:

Recently, the yeast Saccharomyces cerevisiae var. boulardii have attracted the attention of Food Science researchers due to their unique properties, the main among which are probiotics. Thus, research is conducted on the use of this yeast as a starter culture in the technology of yogurt, fermented vegetables, fruit, vegetable juices, as well as beer. This paper is aimed at studying Saccharomyces cerevisiae var. boulardii ‘s fermentation performance compared to top-fermenting brewing yeast strains during fermentation of model nutrient media and beer wort. Fermentation activity of the studied strains was assessed based on the character of fermentation curves, as well as the values of the maximum substrate assimilation rate and apparent degree of fermentation. Moreover, during the study, beer was produced using the yeast Saccharomyces cerevisiae var. boulardii as a starter culture. According to the obtained results, it can be concluded that Saccharomyces cerevisiae var. boulardii have less fermentation activity compared to brewing strains. In turn, beer produced with Saccharomyces cerevisiae var. boulardii significantly differed in physicochemical, microbiological, and organoleptic parameters from the control sample obtained using the 047A brewing strain. Thus, it contained less ethanol and secondary metabolites; however, the concentration of living cells was significantly higher, which indicates a relatively high viability of the yeast Saccharomyces cerevisiae var. boulardii. From an organoleptic point of view, final beer has a positive sensory profile. The aroma of the product had a complex character: it included caramel, spicy, fruity and phenolic notes, as well as smoked and wine elements; while honey was the dominant note of the taste.

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992-1001 T.V. Meledina,, S.G. Davydenko and A.T. Dedegkaev
Yeast Physiological State Influence on Beer Turbidity
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Yeast Physiological State Influence on Beer Turbidity

T.V. Meledina¹,*, S.G. Davydenko² and A.T. Dedegkaev²

¹Saint-Petersburg State University of Information Technologies,Mechanics and Optics (ITMO University) Kronversky pr., 49, St Petersburg, 197101, Russia
²Baltika Breweries - Part of Carlsberg Group, 6 Verkhny per., 3, St Petersburg, 194292, Russia

Abstract:

The physiological state of yeast affects the intensity of propagation and biosynthesis of secondary metabolites and determines the sensory profile of beer. Besides that, yeast with low physiological activity increases the number of colloidal particles in beer, which consist of proteins and polysaccharides. The purpose of this study was to select a method for assessing the physiological state of yeast and to study the influence of yeast physiological state on the adsorption of compounds that determine the colloidal stability of beer. As a result of comparative analysis of different methods for determining the non-viable and weakened cells with dyes a certain correlation between them was found. The highest correlation (R2 = 0.84) was set between parameters obtained by staining yeast cells by methylene blue with Safranin O, which stains both dead and weakened cells and  dihydrorhodamine 123, which detects only physiologically least active yeast. Sufficiently high  correlation (R2 = 0.83) was observed when cells were stained with methylene blue, which identifies only dead cells, and with methylene blue with Safranin O. The worse the physiological condition of yeast, the less they adsorb turbidity-inducing compounds, so more substances remain in beer, reducing its stability. Thus, the increase in the proportion of damaged and non-viable cells from 24.2 to 32.2% leads to increased beer turbidity from 1.5 to 3.3%. Z-potential of yeast cell walls determines their sorption properties. Physiologically active yeast cells are able to adsorb positively charged colloids due to the negative charge of their surface. Activation of the yeast’s surface potential occurs in the presence of oxygen.

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1435–1451 O. Savkina, L. Kuznetsova, O. Parakhina, M. Lokachuk and E. Pavlovskaya
Impact of using the developed starter culture on the quality of sourdough, dough and wheat bread
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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.

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377-388 A. Cristobal-Sarramian and D. Atzmüller
Yeast as a production platform in biorefineries: conversion of agricultural residues into value-added products
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Yeast as a production platform in biorefineries: conversion of agricultural residues into value-added products

A. Cristobal-Sarramian* and D. Atzmüller

University of Applied Sciences Upper Austria, School of Engineering, Stelzhamerstraße 23, AT4600 Wels, Austria
*Correspondence: alvaro.cristobal@fh-wels.at

Abstract:

In contrast to a petroleum-based economy, which relies on the unlimited presence of fossil fuels, a biobased economy utilizes a broad spectrum of natural crops and biomass as raw substrates for the production of valuable materials. Biorefineries represent a promising approach for the co-production of bioenergy (biofuels, biogas) and value-added products (biochemicals, biomaterials, food). Within Europe, wheat straw represents the major crop residue and has been extensively considered as a promising feedstock in the biorefining process. Firstly, wheat straw is hydrolysed to obtain a sugar solution that is further converted into the desired product in a biocatalytic manner. Microbial fermentation is the core component of biorefineries and yeast, as for instance Candida guilliermondii, is an effective production platform for both, biofuels and biochemicals. One limiting aspect in using yeast in the biorefinery approach is the presence of inhibitors in lignocellulosic hydrolysates, such as acetic acid or furfural, influencing cellular growth and diverse metabolic processes. In order to overcome this problem, several genetic engineering approaches are used to increase yeast resistance towards these inhibitors and to enhance the overall production. In this paper, we summarized: 1) the pretreatment technologies for wheat straw bioconversion; 2) the Candida guilliermondii genetic engineering technologies and their biotechnological potential. In conclusion, biorefineries are a crucial factor in the transition towards a biobased and circular economy, and the implementation of yeast into this system offers a great opportunity to develop innovative strategies for a sustainable production in an environmentally friendly and economically feasible manner.

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