E. Korcz

57202642086

Publications - 5

Relationship between total cell counts and exopolysaccharide production of Streptococcus thermophilus T9 in reconstituted skim milk

E. Korcz Z. Kerényi László Varga

Publication Name: Lwt

Publication Date: 2021-08-01

Volume: 148

Issue: Unknown

Page Range: Unknown

Description:

The main objective of this study was to establish a correlation between total bacterial count (TBC) and exopolysaccharide (EPS) production in a specific Streptococcus thermophilus strain. TBC was determined based on real-time quantitative polymerase chain reaction (qPCR) standard curves of S. thermophilus T9 cultured in reconstituted skim milk. EPS yields were measured following isolation and purification steps using a dextran standard curve. The relationship between TBC of and EPS production by S. thermophilus T9 was analyzed alongside these standard curves. The results showed that EPS yield reached 36.6 ± 0.8 mg L−1 following 6 h of incubation. Over the same period, the streptococcal counts measured by qPCR increased from 4.71 ± 0.15 to 7.52 ± 0.09 log10 TBC mL−1. Overall, EPS biosynthesis has been shown to be a growth-related trait in S. thermophilus T9 (R2 = 0.991). In conclusion, the monitoring of TBC may provide an insight into the mechanism of EPS production and, therefore, its use can be recommended for this purpose and for EPS quantification. To our knowledge, this is the first research that has associated qPCR-based TBC with EPS yield in S. thermophilus.

Open Access: Yes

DOI: 10.1016/j.lwt.2021.111775

Exopolysaccharides from lactic acid bacteria: Techno-functional application in the food industry

E. Korcz László Varga

Publication Name: Trends in Food Science and Technology

Publication Date: 2021-04-01

Volume: 110

Issue: Unknown

Page Range: 375-384

Description:

Background: The growing consumer demand for foods that do not contain artificial additives and are “clean labeled” can be addressed in fermented products by using lactic acid bacteria (LAB) capable of synthesizing exopolysaccharides (EPS). There is great variability in LAB-based EPS in terms of quantity, monomer composition, molecular weight, charge, and structure, which results in an array of physicochemical and rheological properties that can be exploited for varied applications in the food industry. Scope and approach: EPS are an alternative class of bio-thickeners widely used in the food industry. This review provides a brief overview of EPS composition and production, and highlights EPS functionality, focusing on specific areas and ways of applying them in food products. Key findings and conclusions: Although EPS-producing LAB strains have been traditionally applied in the manufacture of cultured milks, their use in the production process of low-fat cheeses, different plant-based yogurt alternatives, diverse types of sourdough breads, and reduced-fat fermented meat products are some of the novel applications of these polymers. EPS interact with other food components to improve the rheological and sensory properties of foods and, thus, they can act both as texturizers and stabilizers, increasing the viscosity and mouthfeel of products. Despite the abundance of research findings, a better understanding of the structure–function relationship of EPS in food products still remains a challenge.

Open Access: Yes

DOI: 10.1016/j.tifs.2021.02.014

Serratia fajok jellemzése, valamint Serratia marcescens kvalitatív kimutatása nyers és pasztőrözött tejből polimeráz láncreakción alapuló vizsgálati módszerrel

E. Korcz Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2021-01-01

Volume: 67

Issue: 2

Page Range: 3441-3452

Description:

No description provided

Open Access: Yes

DOI: 10.52091/EVIK-2021/2-4-HUN

Characterization of serratia species and qualitative detection of serratia marcescens in raw and pasteurized milk by an analytical method based on polymerase chain reaction

E. Korcz Z. Kerényi László Varga

Publication Name: Elelmiszervizsgalati Kozlemenyek

Publication Date: 2021-01-01

Volume: 67

Issue: 2

Page Range: 3453-3464

Description:

Serratia species are opportunistic pathogenic microorganisms primarily known as nosocomial infectious agents, which can also cause food quality problems. The appearance of the extracellular pigment-producing Serratia marcescens in cow’s milk causes its red discoloration, posing a challenge to the dairy industry and food certification laboratories. The detection of the bacterium by conventional procedures based on microbiological methods is time-consuming and labor-intensive, and in many cases does not lead to satisfactory results due to the competitive inhibitory effect of the accompanying microflora. Following the analysis of the relevant literature, the published endpoint PCR methods and the primers used for the detection of S. marcescens were evaluated in in silico and in vitro assays, and then the procedure was tested on farm milk samples. Using the method, a total of 60 raw and pasteurized milk samples were analyzed, more than half of which (i.e., 32) were identified as S. marcescens positive. The significance of our work is mainly represented by the application of the published test methods in food industry practice. Our results highlight to the importance of detecting this bacterial species.

Open Access: Yes

DOI: 10.52091/EVIK-2021/2-4-ENG

Dietary fibers, prebiotics, and exopolysaccharides produced by lactic acid bacteria: Potential health benefits with special regard to cholesterol-lowering effects

E. Korcz Z. Kerényi László Varga

Publication Name: Food and Function

Publication Date: 2018-06-01

Volume: 9

Issue: 6

Page Range: 3057-3068

Description:

The gastrointestinal (GIT) microbiota, which plays a crucial role in human health, is influenced by a number of factors including diet. Consumption of specific dietary ingredients, such as dietary fibers and prebiotics, is an avenue by which the microbiota can be positively modulated. These substances may also reduce serum cholesterol levels through various mechanisms. Interest has increased in methods of reducing blood cholesterol level, because dyslipidemia is recognized as a contributory risk factor for the development of cardiovascular diseases. Several drugs have been developed for the treatment of hypercholesterolemia; however, undesirable side effects were observed, which have caused concerns about their long-term therapeutic use. Alternatively, many nonpharmacological approaches were tested to reduce elevated serum cholesterol levels. Dietary fibers and prebiotics have particularly beneficial effects on the GIT microbiome, and can also reduce serum cholesterol level through various mechanisms. Lactic acid bacteria (LAB) are potentially capable of synthesizing different polysaccharides, e.g. exopolysaccharides (EPS), which may play a role as prebiotics. LAB-based EPS have the potential to affect the gastrointestinal microbiome and reduce cholesterol. However, as dietary fibers comprise a complex group of substances with remarkably diverse structures, properties, and impacts, EPS also differ greatly and show a multitude of beneficial health effects. This review discusses the current knowledge related to the effects of dietary fibers and prebiotics on the human GIT microbiome, the prebiotic properties of EPS produced by LAB, and the health-promoting benefits of these polymers with special emphasis being given to cholesterol lowering.

Open Access: Yes

DOI: 10.1039/c8fo00118a