Georgi Kostov

University Of Food Technology - Plovdiv | UFTP · Technology of wine and brewing

The general approaches in the modeling of fermentation processes have been discussed in the present publication. A classification of fermentation processes, some methods of modeling the composition of the culture media and the macrokinetic parameters of the process as a first step in the design of a fermentation process have been considered. The pu...

In order for a strain to be considered a probiotic or suitable plant bioprotective agent, it must have proven antimicrobial activity against pathogenic bacteria and phytopathogenic fungi. Bacillus amyloliquefaciens M exhibited significantly high antifungal activity against pathogenic fungi of the genera Aspergillus, Penicillium, Fusarium, and Scler...

Sourdough starter development includes examination of potential strains of lactic acid bacteria (LAB), propionic acid bacteria and yeasts, selection of suitable strains, development of combinations and examination of the relationships between the strains in each combination, selection of symbiotic combinations and their industrial probation to dete...

Wort-based beverages produced by lactic acid fermentation showed high nutritional value and functional properties but their flavor was not well accepted by consumers. Therefore, raspberry ( Rubus idaeus L) seed oil in concentration of 0.0375% (v/v) was used in order to improve beverage flavor and to increase its biological value. Fermentation was c...

Bacillus amyloliquefaciens M is a non-pathogenic microorganism with probiotic properties isolated from mineral waters in the village of Yabаlkovo, Haskovo region, for inclusion in the composition of probiotics and probiotic foods. It has high antimicrobial activity against pathogenic bacteria, causing food toxic infections and intoxications, as wel...

Species identification is the first step in the examination of newly isolated microorganism strains, including the cases when they are intended for application in the development of probiotic preparations or starters for different food products. The thorough identification process of newly isolated strains combines the application of different phys...

Tailor-made foods, also known as foods with programmable properties, are specialised systems with unique composition prepared by different methods, using the known mechanisms of action of their bioactive ingredients. The development of tailor-made foods involves the evaluation of individual components, including bioactive substances derived from wa...

Beer ranks third in terms of consumption worldwide, and its technology is constantly being improved and perfected. The boom in craft brewing has led to the production of thousands of new types of beer, but most often without scientific justification of the technological decisions made. This paper discusses the approaches to the modeling of the comp...

The growing consumer demand for the development of functional foods with a number of benefits for the consumer has led to a considerable increase in the studies focused on examining different natural agents to be included in the composition of newly developed functional foods. The chemical compositions of the essential oils (EOs) of lavender (Lavan...

In today's dynamic world, it is necessary to explore more alternative options for starch isolation and develop technologies to obtain better quality products. The presence of impurities in the composition of starch is an indicator that affects its properties. Starch was isolated from whole emmer seeds. The present study aims to compare the protein...

Different malt types used in beer production are responsible not only for beer taste and aroma, but also for its biological value. In our previous research the main brewing and biological (phenolic compounds and antioxidant capacity) characteristics of 20 malt types, which are used in the brewing industry in Bulgaria, were studied. The aim of the p...

Batch cultivation in a laboratory bioreactor with stirring of the lactobacilli strains with probiotic properties Lacticaseibacillus casei ssp. casei G17 and Lacticaseibacillus casei ssp. rhamnosus G16 isolated from pink blossom of Rosa damascena Mill was conducted. The changes in the concentration of viable cells were monitored. The growth kinetics...

A Lactobacillus strain was isolated from rose blossom of Rosa damascena Mill. and it was identified as belonging to the species Lactobacillus helveticus by the application of physiological-biochemical (API 50 CHL) and molecular-genetic methods (sequencing of the 16S rRNA gene). The presence of a number of probiotic properties of L. helveticus 2/20...

In today?s dynamic development of food technologies it becomes necessary to study alternative sources of starch to replace the traditionally used ones. Characteristics such as granule size, gelling properties, retrogradation and rheology are fundamental for the selection of starch in the food industry. The aim of the present study is to investigate...

The microbial growth of the probiotic strain Lactobacillus delbrueckii ssp. bulgaricus B1, cultivated in a complex nutrient medium (MRS-broth), was studied in the present work. The complex nutrient medium provides not only the carbon source necessary for the growth of biomass, but also all the additional sources of nitrogen, phosphorus and other co...

The influence of the two technological parameters, temperature (20 °C, 24 °C, 28 °C) and the inoculum amount of the yeast culture (2%, 3%, 4%) on the duration of the alcoholic fermentation and the ester-producing capacity of the Badachoni and the 24-6 strains of Saccharomyces cerevisiae species was studied. The yeast exhibited high fermentation act...

Probiotic bacteria are used for food biopreservation because their metabolic products might contribute to ensuring food microbiological safety and/or increase its shelf life without the addition of chemical preservatives. Moreover, biopreserved foods are excellent vehicles for the delivery of probiotic bacteria. The aim of the study was to investig...

Wort can be used as a basis for functional beverages production because of its content of fibres, antioxidants and vitamins. The biological value of wort depends on the malt used and the mashing regime. Therefore, we investigated the main brewing characteristics (extract, pH, and colour), phenolic compounds content, and antioxidant activity (measur...

Monitoring of bioprocesses is a challenge in designing modern systems for control. In the biotechnology industry, the lack of reliable hardware sensors for key variables related to the metabolism of microorganisms is a topical problem. This predetermines the progress of a scientific field that relies on the development of software sensors for immea...

The microbial growth of the probiotic strain Lactobacillus delbrueckii ssp. bulgaricus B1, cultivated in a complex nutrient medium (MRS-broth), was studied in the present work. The complex nutrient medium provides not only the carbon source necessary for the growth of biomass, but also all the additional sources of nitrogen, phosphorus and other co...

The influence of temperature and inoculum amount of yeast culture on the ability of the strains Saccharomyces cerevisiae Badachoni and Saccharomyces cerevisiae 24-6 to synthesize higher alcohols and aldehydes was studied. Yeast showed the highest fermentation activity at a temperature of 28oC. Neural networks had been applied and mathematical model...

An interesting property for many probiotic strains is to exhibit antimicrobial activity against pathogenic microorganisms. Therefore, the antimicrobial activity of the potentially probiotic strain Lactobacillus acidophilus L12 against Escherichia coli, Staphylococcus aureus and Salmonella sp. was examined in vitro through co-culturing of Lactobacil...

The antimicrobial activity of potentially probiotic strains is important for their possible application in the development of successful strategies for bio-preservation of different foods. The antimicrobial activity of the potentially probiotic strain Lactobacillus plantarum L4 against the pathogenic bacteria Salmonella abony ; Staphylococcus aureu...

Beer production has over a thousand-year tradition, but its development in the present continues with the introduction of new technological and technical solutions. The methods for modeling and optimization in beer production through an applied analytical approach have been discussed in the present paper. For this purpose, the parameters that are e...

The study of the growth kinetics of lactobacilli with pronounced probiotic properties in their batch cultivation is essential. Various models based on the logistic curvemodel, containing parameters showing the influence of the accumulating lactic acid on the biosynthesis of the product, as well as parameters showing the sensitivity of the cells to...

The ability of two Saccharomyces cerevisiae strains (Bordeaux, 8-11) to produce carbonyl compounds under different conditions of the alcoholic fermentation was investigated. The impact of the temperature and the inoculum yeast culture ratio on the synthesis of total aldehydes during the process was traced. A more pronounced effect of the temperatur...

Lactic acid wort-based beverages are functional, non-alcoholic, with low pH value and produced by the fermentation of wort by lactic acid bacteria. They are not well accepted by consumers because of their poor sensory characteristics. Therefore, 0.025 and 0.05 % (v/v) mint (Mentha piperita) essential oil was used as a tool for improvement of lactic...

Lactic acid wort-based beverages are functional, non-alcoholic, with low pH value and produced by the fermentation of wort by lactic acid bacteria. They are not well accepted by consumers because of their poor sensory characteristics. Therefore, 0.025 and 0.05 % (v/v) mint (Mentha piperita) essential oil was used as a tool for improvement of lactic...

The species Trametes versicolor refers to medicinal mushroom well known in traditional Asian medicine for over 2000 years. Due to the long time required for basidiocarp formation, attention has recently been given to the submerged cultivation method for the production of mycelial biomass and various bioactive components. Exopolysaccharides (EPS) pr...

Malt is the main raw material for beer production, which determines not only its taste and aroma profile, but to a large extent its biological value, as well. The aim of the present research was to determine the antioxidant profile of different malt types as a basis for the development of new types of beer with increased antioxidant activity. In th...

The study of the growth kinetics of lactobacilli with pronounced probiotic properties in their batch cultivation is essential. Various models based on the logistic curve model, containing parameters showing the influence of the accumulating lactic acid on the biosynthesis of the product, as well as parameters showing the sensitivity of the cells to...

The monitoring of the main variables and parameters of biotechnological processes is of key importance for the research and control of the processes, especially in industrial installations, where there is a limited number of measurements. For this reason, many researchers are focusing their efforts on developing appropriate algorithms (software sen...

Background: In recent years, increasing health awareness in consumers has motivated breweries to expand their beverage ranges with products with increased biological value. The aim of the present research was to develop probiotic wort-based beverages with grapefruit or tangerine zest essential oil addition. Methods: Wort was produced with 60% Pi...

Response justifying objections to the article: Kostov et al. Biopreservation of emulsified food and cosmetic products by synergistic action of probiotics and plant extracts: a Franco-Bulgarian perspective, published in Food Science and Applied Biotechnology, 2020, Vol. 3., Iss. 2, pp. 167-184, https://doi.org/10.30721/fsab2020.v3.i2.93 .

The combination of modified mashing method and arrested fermentation for the production of low-alcohol and non-alcohol beers was studied. Therefore, five regimes for fermentation of wort with reduced fermentable sugar content with top-fermenting yeast strain at low temperatures and pitching rates were investigated. According to the fermentation dyn...

Blagoeva, N., Bazhlekova, I., Spasov, H. & Kostov, G. (2020). Influence of enzyme maceration and alcoholic fermentation temperature on the terpenes concentration in Muscat wine distillates. Bulg. J. Agric. Sci., 26 (5), 1069-1075 Various factors in grape processing are influencing terpene content in wines and base wine for distillation. The choice...

In the present study, a comparative analysis was undertaken on the possibilities of using olive oil in fresh spreadable cheese either emulsified or encapsulated. The changes in titratable acidity, active acidity and total Lactococcus count were recorded continuously throughout the storage period. At the end of the storage period, Lactococcus count...

In this study, different variants of egg-free mayonnaise containing free and immobilized Lactobacillus plantarum LBRZ12 cells and essential oils taken from basil and dill were prepared. The composition and antimicrobial properties of essential oils were investigated. The main constituents of basil oil were methyl chavicol (36.81%), methyl eugenol (...

In the context of growing interest for functional foods and cosmetic products, emulsified products such as dressings or lotions have been proposed to deliver probiotics and plant extracts with interesting biological (e. g. anti-inflammatory) properties due to their daily consumption or application on skin, respectively. Besides these positive effec...

Brewers’ spent grains (BSG) are the main waste product of the brewing industry, accounting for about 85% of the total waste materials. Their composition is different (due to various brewing technologies) but includes high levels of dietary fiber, proteins, essential amino acids, polyphenols, antioxidants, vitamins and fats. The aim of the present s...

The ester producing capacity of two strains of Saccharomyces cerevisiae was investigated, depending on the alcoholic fermentation conditions of grape pulp from Cabernet Sauvignon variety. The influence of the temperature (20°C, 24°C, 28°C) and the inoculum amount of yeast culture (2%, 3%, 4%) on the total esters synthesized during the process was m...

Three different kinetic models – Monod’s model, Monod’s model with substrate inhibition, and Monod's model with substrate and product inhibition were developed for studying of beer fermentation with free and immobilized cells at different main fermentation and maturation temperatures. The most accurate model was Monod's model with substrate and pro...

A series of wort fermentations with eight yeast strains were carried out in laboratory conditions. The strains used were: Saccharomyces cerevisiae (2 strains), Saccharomyces diastaticus (3 strains), Saccharomyces carlsbergensis (1 strain), Saccharomyces lactis (1 strain), Saccharomyces sake gekkeikan (1 strain). Selection of yeast strains has been...

This study aims to investigate the chemical composition, antioxidant, and antimicrobial activity of Citrus aurantium L zest essential oil. The identification of the chemical compounds was done using chromatography analysis. The antioxidant activity was studied by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Results showed that...

The paper discusses meaning construction of English and Bulgarian container terms used in beverage production. Corresponding terminological units afford access to similar concepts; however, the lexical form-meaning complexes in the two languages frequently differ owing to the interaction between linguistic and extralinguistic factors in conceptual...

An interactive user-friendly software system for structural and parametrical identification of concrete bioprocess models is proposed. It is based on optimization programs using evolutionary algorithm which are built in Graphical User Interface Development Environment (GUIDE) of MATLAB. A description of the system structure is given. The user could...

Lipase production during submerged cultivation of Aspergillus carbonarius NRRL369 was studied. In order to increase lipase activity an optimal composite design was applied. Optimal concentrations of the nutrient medium components were found to be (g/l): rapeseed oil 20.0, Tween 80 20.0, meat extract 5.6, MgSO 4 1.0, and KH 2 PO 4 4.0. The result wa...

FAO/WHO define probiotics as "live microorganisms which when administered in adequate amounts confer a health benefit to the host". The administration of probiotics results in the prevention of a number of physical conditions and diseases and the prophylaxis and treatment of others. There are a number of requirements for probiotic strains in order...

Encapsulation is a process of incorporation of bioactive substances in a specific matrix. It results in increasing and/or maintaining of the biological agent concentration in the food matrix or the fermentation system. The encapsulation process is influenced by various factors. The aim of the present work was to investigate the influence of alginat...

It is well-known that olive oil consumption is associated with a number of health benefits to humans due to its fatty acid composition. Because of these characteristics, olive oil can be suitably included in dairy products in order to improve their fatty acid composition. The present study investigated the possibilities of incorporating olive oil i...

Four popular spices black pepper (Piper nigrum L.), cumin (Cuminum cyminum L.), coriander (Coriandrum sativum L.) and cardamom (Elettaria cardamomum) were analyzed for their oil composition by GC-MS. Thirty compounds were identified in the black pepper oil and the main components were β-caryophyllene (20.225 %), sabinene (18.054 %), limonene (16.92...

Phytosterols, phytostanols and their esters have proven health beneficial effects on the human body – they lower the serum cholesterol levels and have potential in inhibiting cancers. The antimicrobial activity of the phytosterol ester against pathogenic and saprophytic microorganisms at different pH values was determined using the well-diffusion m...

The antimicrobial activity of Lactobacillus plantarum BZ1 and Lactobacillus plantarum BZ2 against Escherichia coli ATCC 25922 and Escherichia coli ATCC 8739 in co-culture and at single strain culture at a temperature of 37±1°C was examined. During co-cultivation an increase in the concentration of viable lactobacilli cells by the 24th h was establi...

Low-alcohol beer can be obtained by physical and biological methods. The group of biological methods includes modification of the mashing regimes and changes in the fermentation process. The aim of the present work was to study two mashing regimes for low-alcohol beer production. The increase in the mashing duration at 50 °C led to a linear increas...

The development of new food products enriched with biologically active components is a topical issue for modern food science and practice. Many of these substances are unstable when being incorporated into the food matrix, which demands a study on the possibilities to stabilize them before use. Encapsulation of biologically active substances is a m...

A study on the kinetics of alcohol fermentation for the production of beer with free and immobilized Saccharomyces cerevisiae Safbrew S-33 cells was conducted using three kinetic models. The process was best described by Monod model with product and substrate inhibition. The kinetic parameters showed a less pronounced impact on ester and higher alc...

In recent years, the immobilization of yeast cells and their application in brewing has been the subject of research due to their main advantages: enhanced fermentation productivity, reduced fermentation time, easier implementation of continuous operation, improved cell stability, facilitated cell recovery and biomass reuse. The purpose of the pres...

Yogurt supplies the organism with proteins, lipids, carbohydrates, vitamins and microelements and imports active yogurt microflora. Therefore traditional yogurt is a suitable basis for the development of new functional foods. Starter culture development, including strain property studies and development of symbiotic relationships between the strain...

The influence of the temperature and the duration of the extraction on the composition and the properties of extracts of Alchemilla mollis were investigated. The extraction of lady's mantle (A. mollis) was carried out with 20 % (v/v) aqueous ethanol solution, at a temperature from 15 to 90 °C and duration from 1 to 72 hours. The raising of the extr...

A batch process of culturing of the strain Lactobacillus plantarum BG24, both in dynamic and in static conditions, was performed. It was found that in both types of culture high numbers of viable cells (10 15 cfu/cm 3), which is a requirement for probiotic microorganisms, were accumulated. The results of the mathematical modeling showed that in the...