- 26 Maritza Blvd,
4000 Plovdiv,
Bulgaria
Angel Angelov
University of Food Technologies - Plovdiv, Biotechnology, Faculty Member
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Research Interests: Food Science, Biology, Medicine, Bacteria, Yeast, and 3 moreMicroorganisms, Lactic Acid, and Starter
Research background. Sourdough is a spontaneously formed, complex microbial ecosystem of various lactic acid bacteria (LAB) and yeast which, by producing specific metabolites, determines the quality of the baked products. In order to... more
Research background. Sourdough is a spontaneously formed, complex microbial ecosystem of various lactic acid bacteria (LAB) and yeast which, by producing specific metabolites, determines the quality of the baked products. In order to design and control the sourdough with preferred nutritional characteristics, it is crucial that the LAB diversity ofthe product of interest be elucidated. Experimental approach. Using the opportunities of next-generation sequencing (NGS) of the V1–V3 hypervariable gene region of 16S rRNA, we studied the microbial ecosystem of a whole grain sourdough made of Triticum monococcum, originating from Southwestern Bulgaria. Since the DNA extraction method is considered crucial for the accuracy of the sequencing results, as it can introduce significant differences in the examined microbiota, we used three different commercial kits for DNA isolation and analyzed their impact on the observed bacterial diversity. Results and conclusions. All three DNA extraction k...
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Fermented plant-based foods, including sauerkraut, offer high nutritional and functional value. Their microflora is dominated by lactic acid bacteria which are a source of different substances with health- promoting benefits and diverse... more
Fermented plant-based foods, including sauerkraut, offer high nutritional and functional value. Their microflora is dominated by lactic acid bacteria which are a source of different substances with health- promoting benefits and diverse applications in the food industry. Production of exopolysaccharides (EPSs) by lactic acid bacteria attracts particular interest in the food industry due to their rheological properties. In the present study, we isolated 20 strains of lactic acid bacteria from traditional Bulgarian sauerkraut. The isolates were identified by 16S rDNA sequencing and were attributed to Lactiplantibacillus plantarum (75%) and Pediococcus pentosaceus (25%). All strains were screened for their ability to synthesize exopolysaccharides, and 6 of them proved positive. Since culture media composition and especially the carbon source is a critical factor influencing the yield of bacterial EPSs, the impact of various carbon sources on the EPSs synthesis by the selected producers...
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Food adulteration regarding species origin of meats is a common problem in the meat products sector. With regard to horse meat, its undeclared use in food products is not only a fraud, but could present a health risk since is often... more
Food adulteration regarding species origin of meats is a common problem in the meat products sector. With regard to horse meat, its undeclared use in food products is not only a fraud, but could present a health risk since is often associated with the presence of the veterinary drug phenylbutazone in meat products. Therefore, it is important to use reliable methods for authentication of meat products regarding their species composition, which are applicable to complex food matrices. Polymerase chain reaction (PCR) with species-specific primers remains the most widely used analytical approach to detect species-related food adulteration due to its high sensitivity and specificity. The aim of the present study was to establish the authenticity of 20 different meat products on the Bulgarian market without declared horse meat content by using a species-specific PCR method. The specificity test of the PCR method used showed no amplification of DNA from beef and pork. A detection limit of ...
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Through the use of the immunoaffinity clean-up procedure for extraction of ochratoxin A by high immunoaffinity columns by means of the analytical methodology known as HPLC-FD we have analyzed the quantity of ochratoxin A in 22 must and... more
Through the use of the immunoaffinity clean-up procedure for extraction of ochratoxin A by high immunoaffinity columns by means of the analytical methodology known as HPLC-FD we have analyzed the quantity of ochratoxin A in 22 must and wine samples during alcoholic fermentation process. Analysis of the samples was done in the University of Food Technologies, Plovdiv – Bulgaria.OTA quantities in all analyzed samples have been under the level allowed by EU for ochratoxin A i.e. 2 ng/ml and as such these wines after consuming do not pose a risk in the future to human health.
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In this study work we have determined the quantity of ochratoxin A (OTA) in 54 samples of bottled wine. The methodology which we used is the method known as High Performance Liquid Chromatography with Fluorescence Detection (HPLC). Before... more
In this study work we have determined the quantity of ochratoxin A (OTA) in 54 samples of bottled wine. The methodology which we used is the method known as High Performance Liquid Chromatography with Fluorescence Detection (HPLC). Before the HPLC analysis we have done the ochratoxin A extraction through the immunoaffinity clean-up procedure by high immunoaffinity columns. Samples that are analyzed have been taken in Kosovo and are wine samples produced and bottled in Republic of Kosovo and the wine samples produced, bottled and imported in Kosovo from other Balkan and Europian Union (EU) countries and beyond. The aim of this research has been the analysis of ochratoxin A in bottled wine for the first time in Kosovo and determination of the risk or not by consumption of the analyzed wines by consumers. The results of all analyzed samples have been below the limit allowed by the EU for ochratoxin A i.e. 2 ng/ml and as such in the future do not pose a risk to human health.
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For quantitative analysis of ochratoxin A in must we have used the analytical method known as HPLC-FD and previously used the immunoaffinity clean-up procedure for extraction of ochratoxin A by high immunoaffinity columns. We have... more
For quantitative analysis of ochratoxin A in must we have used the analytical method known as HPLC-FD and previously used the immunoaffinity clean-up procedure for extraction of ochratoxin A by high immunoaffinity columns. We have determined the quantity of OTA in 30 must samples. Samples that are analyzed have been taken in the vineyards of Kosovo, concretely in southern part of Kosovo, in Rahoveci and Suhareka region. The results of all analyzed samples have been below the limit allowed by EU for ochratoxin A i.e. 2 ng/ml and as such in the future do not pose a risk to human health. The must grape represents the grape juice from which by means of certain technological processes, in particular alcoholic fermentation process created wine booze. A quantitative determination of ochratoxin A in must is very important to have in early stage of the technological process of winemaking an overview regarding the presence or not of substances dangerous to human health as is in this case the ...
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Sourdoughs (SDs) are spontaneously formed microbial ecosystems composed of various species of lactic acid bacteria (LAB) and acid-tolerant yeasts in food matrices of cereal flours mixed with water. To date, more than 90 LAB species have... more
Sourdoughs (SDs) are spontaneously formed microbial ecosystems composed of various species of lactic acid bacteria (LAB) and acid-tolerant yeasts in food matrices of cereal flours mixed with water. To date, more than 90 LAB species have been isolated, significantly impacting the organoleptic characteristics, shelf life, and health properties of bakery products. To learn more about the unique bacterial communities involved in creating regional Bulgarian sourdoughs, we examined the metacommunities of five sourdoughs produced by spontaneous fermentation and maintained by backslopping in bakeries from three geographic locations. The 16S rRNA gene amplicon sequencing showed that the former genus Lactobacillus was predominant in the studied sourdoughs (51.0–78.9%). Weissella (0.9–42.8%), Herbaspirillum (1.6–3.8%), Serratia (0.1–11.7%), Pediococcus (0.2–7.5%), Bacteroides (0.1–1.3%), and Sphingomonas (0.1–0.5%) were also found in all 5 samples. Genera Leuconostoc, Enterococcus, Bacillus, a...
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Exopolysaccharides (EPSs) produced by lactic acid bacteria present a particular interest for the food industry since they can be incorporated in foods via in situ production by selected starter cultures or applied as natural additives to... more
Exopolysaccharides (EPSs) produced by lactic acid bacteria present a particular interest for the food industry since they can be incorporated in foods via in situ production by selected starter cultures or applied as natural additives to improve the quality of various food products. In the present study, 43 strains were isolated from different plant-based fermented foods and identified by molecular methods. The species found were distinctively specific according to the food source. Only six Lactiplantibacillus plantarum strains, all isolated from sauerkraut, showed the ability to produce exopolysaccharide (EPS). The utilization of glucose, fructose and sucrose was explored with regard to EPS and biomass accumulation by the tested strains. Sucrose was clearly the best carbon source for EPS production by most of the strains, yielding up to 211.53 mg/L by strain Lactiplantibacillus plantarum ZE2, while biomass accumulation reached the highest levels in the glucose-based culture medium....
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The present study aimed to obtain good quality croissants from wholegrain wheat flour using baking sourdoughs prepared from single starter cultures of Pediococcus acidilactici 02P108 (PA), Pediococcus pentosaceus SM2D17 (PP)... more
The present study aimed to obtain good quality croissants from wholegrain wheat flour using baking sourdoughs prepared from single starter cultures of Pediococcus acidilactici 02P108 (PA), Pediococcus pentosaceus SM2D17 (PP) and Enteroccocus durans 09B374 (ED) as an attempt to overcome the usual negative effects of the wholegrain flour on the characteristics of this specific bakery product group. Results showed that the addition of sourdough in the wholegrain wheat dough had similar performance as that of conventional baker’s yeast regarding the rheological characteristics of dough. The dynamic viscosity of all sourdough-leavened samples remained higher than that of the control sample at all tested shear rates. A positive effect of sourdoughs used on the development of baking dough was observed in terms of specific volume improvement, higher degree of softening, and reduced baking loss. However, these positive effects were found as strain-specific. The use of Enteroccocus durans 09B...
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In an investigation of the changes in the microflora along the pathway: kefir grains (A)-->kefir made from kefir grains (B)-->kefir made from kefir as inoculum (C), the following species of lactic acid bacteria (83-90%) of... more
In an investigation of the changes in the microflora along the pathway: kefir grains (A)-->kefir made from kefir grains (B)-->kefir made from kefir as inoculum (C), the following species of lactic acid bacteria (83-90%) of the microbial count in the grains) were identified: Lactococcus lactis subsp. lactis, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lactobacillus casei subsp. pseudoplantarum and Lactobacillus brevis. Yeasts (10-17%) identified were Kluyveromyces marxianus var. lactis, Saccharomyces cerevisiae, Candida inconspicua and Candida maris. In the microbial population of kefir grains and kefir made from them the homofermentative lactic streptococci (52-65% and 79-86%, respectively) predominated. Within the group of lactobacilli, the homofermentative thermophilic species L. delbrueckii subsp. bulgaricus and L. helveticus (70-87% of the isolated bacilli) predominated. Along the pathway A-->B-->C, the streptococcal proportion in the total kefir microflora increased by 26-30% whereas the lactobacilli decreased by 13-23%. K. marxianus var. lactis was permanently present in kefir grains and kefirs, whereas the dominant lactose-negative yeast in the total yeast flora of the kefir grains dramatically decreased in kefir C.
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Research Interests: Engineering, Technology, Biotechnology, Biomass, Nanoparticles, and 14 moreTransmission Electron Microscopy, Biological Sciences, Glucose, Heavy Metal, Detoxification, Cadmium, Schizosaccharomyces Pombe, Candida Glabrata, Bioreactors, Molecular weight, Cell Wall, Batch Process, Size Exclusion Chromatography, and Sulfates
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Research Interests: Microbiology, Probiotics, Kinetics, Refrigeration, Industrial Biotechnology, and 14 moreFood Microbiology, SHELF LIFE, Lactic Acid Bacteria, Lactobacillus, Fermentation, Beverages, Time Factors, Beta-Glucans, Food Sciences, Whole Grain, Food Handling & Hygiene, Starter Culture, Hydrogen-Ion Concentration, and Fermentation Process
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ABSTRACT
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The increasing number of commercialized GM crops and the growing need for authenticity control of raw materials, feeds and foods set an urgent necessity for the development of sensitive, reliable and cost-effective methods for GMO... more
The increasing number of commercialized GM crops and the growing need for authenticity control of raw materials, feeds and foods set an urgent necessity for the development of sensitive, reliable and cost-effective methods for GMO detection. In the present study, a novel multiplex PCR method for the simultaneous detection of all EU-authorized genetically modified soybean events was developed. The method was based on three gene-specific (EPSPS, PAT and Cry1Ac genes) and one event-specific (DP 356043) DNA sequences. It was characterized with high sensitivity, as the LOD for each sequence was 0.05%. The new method was applied for the screening of 15 soybean products and 36 meat products at the market for the presence of genetically modified soybean events. Results demonstrated that 51% of the tested samples contained EPSPS gene, while PAT gene was detected in 8% of the DNA extracts. In contrast to that, Cry1Ac gene and DP 356043 event-specific sequence were not observed in any of the a...
Grapes (Vitis vinifera L.) are an essential crop for fresh consumption and wine production. Vineyards are attacked by several economically important bacterial and fungal diseases that require regular pesticide treatment. Among them,... more
Grapes (Vitis vinifera L.) are an essential crop for fresh consumption and wine production. Vineyards are attacked by several economically important bacterial and fungal diseases that require regular pesticide treatment. Among them, Pseudomonas syringae pv. syringae (Ps. syringae) and Botrytis cinerea (B. cinerea) infections cause huge economic losses. The fresh fruit market has shifted to functional natural foodstuffs with clear health benefits and a reduced use of chemicals along the production chain. Lactic acid bacteria (LAB) have a biopreservative effect and are applied to ensure food safety in response to consumers’ demands. In the present study, the possibilities of using microorganisms with a potential antimicrobial effect against Ps. syringae and B. cinerea in the production of table grapes were investigated. LAB of the genus Lactiplantibacillus can be a natural antagonist of pathogenic bacteria and fungi by releasing lactic acid, acetic acid, ethanol, carbon dioxide and ba...
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Production of gluten-free bread (GFB) with good quality characteristics represents a technological challenge. Our study aimed to obtain nongluten bread from cereals and pseudocereals with applying single cultures of Pediococcus... more
Production of gluten-free bread (GFB) with good quality characteristics represents a technological challenge. Our study aimed to obtain nongluten bread from cereals and pseudocereals with applying single cultures of Pediococcus acidilactici, Pediococcus pentosaceus and Enteroccocus durans as sourdoughs. The effect of sourdoughs on the quality traits of gluten-free (GF) dough and GFB was explored. The structural and baking properties of GF dough composed of teff, rice, corn, and sorghum flours were improved by adding xanthan gum (0.6%), guar gum (1.0%) and carboxymethyl cellulose (1.0%). The tested strains reached 108 cfu/g in teff flour and produced sourdoughs with a pleasant lactic aroma. The sourdough-fermented doughs were softer and more elastic compared to control dough and yielded reduced baking loss. Strain Enterococcus durans ensured the best baking characteristics of GF dough and the highest softness of the GFB during storage. Strain Pediococcus pentosaceus had the most pron...
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The increasing number of commercialized GM crops and the growing need for authenticity control of raw materials, feeds and foods set an urgent necessity for the development of sensitive, reliable and cost-effective methods for GMO... more
The increasing number of commercialized GM crops and the growing need for authenticity control of raw materials, feeds and foods set an urgent necessity for the development of sensitive, reliable and cost-effective methods for GMO detection. In the present study, a novel multiplex PCR method for the simultaneous detection of all EU-authorized genetically modified soybean events was developed. The method was based on three gene-specific (EPSPS, PAT and Cry1Ac genes) and one event-specific (DP 356043) DNA sequences. It was characterized with high sensitivity, as the LOD for each sequence was 0.05%. The new method was applied for the screening of 15 soybean products and 36 meat products at the market for the presence of genetically modified soybean events. Results demonstrated that 51% of the tested samples contained EPSPS gene, while PAT gene was detected in 8% of the DNA extracts. In contrast to that, Cry1Ac gene and DP 356043 event-specific sequence were not observed in any of the a...
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Black chokeberry (Aronia melanocarpa) is a plant with unique health-promoting properties due to the high content of vitamins and polyphenols in its fruits. Despite their high resistance to spoilage, chokeberry fruits may get contaminated... more
Black chokeberry (Aronia melanocarpa) is a plant with unique health-promoting properties due to the high content of vitamins and polyphenols in its fruits. Despite their high resistance to spoilage, chokeberry fruits may get contaminated with mycotoxin-producing fungi. In the present study, samples of chokeberry fruits were collected from seven different sites in Bulgaria and their fungal profile was investigated. The most common moulds in fresh chokeberry were Penicillium sp. (77.5% out of all isolates), followed by Alternaria sp. (14.5%) and Bothrytis sp. (8%). Eighteen randomly chosen Penicillium isolates were further screened by enzyme-linked immuno sorbent assay (ELISA) for their ability to produce ochratoxin A (OTA) in liquid yeast extract sucrose medium. Four of the tested isolates (no. 11 from the region of Panagiurishte, no. 2 and 10 from the region of Plovdiv and no. 47 from the region of Koprivshtitsa) showed ability to produce OTA in concentrations 15.42, 14.62, 19.75 and 20.97 ng/ml, respecti...
Research Interests: Biology and Food Sciences
Many of the indigenous foods consumed around the world are produced by natural fermentation. Information is not always available about the microorganisms involved, which makes it very difficult to maintain the product quality. In this... more
Many of the indigenous foods consumed around the world are produced by natural fermentation. Information is not always available about the microorganisms involved, which makes it very difficult to maintain the product quality. In this work the microflora of the traditional Bulgarian cereal-based beverage boza was investigated and some of the yeast and lactic acid bacteria strains have been identified and quantified. Although further work is needed to identify what microorganisms are responsible for the beneficial properties of ...
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Abstract: Fermentation of a prebiotic containing oat substrate with probiotic lactic acid bacteria and yeast strains is an intriguing approach for the development of new synbiotic functional products. This approach was applied in the... more
Abstract: Fermentation of a prebiotic containing oat substrate with probiotic lactic acid bacteria and yeast strains is an intriguing approach for the development of new synbiotic functional products. This approach was applied in the present work by using pure and mixed ...