bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of conventional and organic agriculture practices on the total phenols and antioxidant potential of Florina apple fruits
Authors: Petkova N Tr , Kuzmanova S , Bileva T , Valcheva Ek , Dobrevska G , Grozeva N , Popov V 
Published: February 2021

Abstract
The aim of the current study was to evaluate the influence of conventional and organic growing conditions on the total phenolic content, the total flavonoids content, the total monomeric anthocyanins content and the antioxidant potential in the apple fruits of Florina variety. The samples were grown and collected from the experimental fields, around Plovdiv and the village of Brestnik. The total phenolic content, the total flavonoids, the total monomeric anthocyanins content were determined. The antioxidant potential was evaluated by four different assays. The apple fruits grown under organic conditions contained higher total phenolics and they showed stronger antioxidant activity than fruits from the conventional conditions. The total phenolic content was from 3 to 5 mg gallic acid equivalent/g dry weight. The total flavonoids were below 1 mg quercetin equivalents/g dw. In the organically grown fruits, the average values for antioxidant activity varied from 30 to 100 mM Trolox® equivalent/g dw. The total monomeric anthocyanins in the organically grown apples their levels were the highest (67 mg cyn-3-glc/100 g dw). There was a positive, high correlation between antioxidant methods and the total phenolic content and total monomeric anthocyanins. These results indicated that organically grown apples accumulated higher levels of antioxidants and bioactive compounds, in comparison to conventionally grown apples.
Determination of viscosity in O/W emulsions and correlation with prime oil phase
Authors: Tasheva S Tz , Gandova V D , Petrova I G , Dobreva K Z 
Published: February 2021

Abstract
Oil-in-water (O/W) emulsions with 10%, 20%, 30% and 40% oil were prepared using soybean protein isolate (SI) 1, 2 and 3% as stabilizer. Viscosity of emulsions was determined. Microscope observation of all emulsions immediately after preparation was performed. Correlation among viscosity, emulsion droplet size and percents of oil phase were found. Emulsions prepared with high percent oil exhibit smaller average droplet size and greater stability.
Coefficient of diffusion of tannins in ethanol extracts from Physalis alkekengi L. leaves
Authors: Popova V T , Tasheva S T , Ivanova T A , Stoyanova A S 
Published: February 2021

Abstract

Physalis alkekengi L. (Solanaceae) is a wild growing plant, native to Bulgaria. The plant produces edible fruit rich in phytonutrients; the fruit and the leaves have been used in Bulgarian and other folk medicines for centuries. The leaves of P. alkekengi can be considered as a promising resource for obtaining extracts rich in bioactive ls is performed by molecular diffusion; a generalized indicator of the diffusive properties is the coefficient of diffusion (D). It takes individual values for different plant matrices and depends on various factors in the mass transfer process. To the best of our knowledge, there are no data about the diffusion coefficients of tannins in P. alkekengi leaf extracts, which was set as the objective of the study. Extraction was carried out in a batch static mode, under the following conditions: raw material to solvent ratio of 1:33 (w/v); size of leaf particles – 0.0125 m χ 0.002 m; duration of extraction – 1 h, with the solvent being replaced and analyzed for extracted tannins after each 600 s; solvents – 95%, 70%, 50%, and 30% ethanol; temperature – 20°C, 40°C and 60°C. The values of the coefficient showed variation over time and temperature, for each of the solvents. The highest D value obtained was 0.1690.10-9 m2.s-1 (70% ethanol, 60°C). These are the first data about the coefficient of diffusion of tannins in ethanol extracts from Physalis alkekengi L. leaves.
Correlation between phenotypic characteristics of chemical composition and rennet coagulation of sheep milk
Authors: Kalaydzhiev G I , Balabanova T B , Ivanova M G , Ivanov G Y 
Published: February 2021

Abstract
The aim of the present study was to establish a correlation between phenotypic characteristics of chemical composition, somatic cell count and rennet coagulation of sheep milk during different stages of lactation. The experimental milk samples were taken from Bulgarian autochthonous sheep breed-Local Stara Zagora sheep, newly developed breed-Bulgarian dairy synthetic population (BDSP), and Lacaune sheep breed. From the data obtained about the chemical composition of sheep milk, it was established that Bulgarian dairy synthetic population sheep breed had the highest fat value – 9.50%, whereas for the other breeds the fat value was approximately 8.30%. A slight variation in values for protein, lactose, solids-non-fat (SNF) and density was observed in the individual milk samples. The determined somatic cell count in the experimental samples ranged from 11 400 to 9 560 866 cells/ml, as the average value for the whole lactation period was 643 259 cells/ml. Strong negative correlation between somatic cell count value and parameters of milk coagulation ability was also established – SSC:RCT (-0.170); SCC:K20 (-0.142) and SCC:A30 (-0.254). The collected data showed undeniably that in order to improve rennet coagulation of sheep milk, conduction of thorough research, analysis and evaluation of milk productivity was needed, as well as application of selective breeding approaches and reduction of somatic cell count in milk.
Green approach to obtain extracts of seven edible flowers
Authors: Petkova D T , Mihaylova D Sp , Deseva I.N. , Denev P N , Krastanov A I 
Published: February 2021

Abstract
Edible flowers are considered as a valuable source of bioactive compounds and are used as food and medicine with growing interest. Microwave extraction technique was employed as a green approach to obtain water extracts from seven edible flowers including Viola tricolor L., Cucurbita pepo L., Sambucus nigra L., Calendula officinalis L., Hibiscus rosa-sinensis L., Rosa damascena Mill. and Allium ursinum L. They were characterized in terms of total content of phenolics and flavonoids, as well as antioxidant potential. The total phenolic content in the edible flower’s extracts ranged between 12.08 ± 0.09 and 72.66 ± 0.60 mg gallic acid equivalent (GAE)/g dw and the total flavonoid content was established to vary between 2.36 ± 0.09 and 25.91 ± 0.09 mg quercetin equivalents (QE)/g dw. The highest values were reported in the extracts of Viola tricolor and Rosa damascena. Moreover, the same extracts displayed the highest antioxidant activity evaluated by six in vitro assays. The lowest activity was detected in the A. ursinum and C. pepo flowers extracts. In addition, the correlation between the conducted assays was studied. In conclusion, all of the studied edible flowers can be considered as promising sources of natural antioxidants in the food industry.
Comparative characteristics of instant creams with sugar and isomaltulose
Authors: Hadjikinova R D 
Published: February 2021

Abstract
In recent years, there has been a trend to replace sugar (sucrose) in the composition of foods with sweet taste, with its alternatives that have a beneficial effect on some of the functions of the human body. One of the newest alternatives to sucrose is isomaltulose, which differs from other sugars by its low glycemic index and its non-cariogenicity. The aim of the present study was to establish the influence of isomaltulose, as a substitute for sucrose in the composition of instant starch creams, on their main physicochemical parameters and properties. Based on a comparative analysis, the main physicochemical parameters and the rheological behavior of instant starch creams obtained with sucrose and isomaltulose were determined. It was found that differences between the samples exist in the indicator-content of reducing substances and the values of glycemic indicator. No differences were observed in the rheological behavior of the creams, similar to the cream with sugar, the cream with isomaltulose refers to non-Newtonian liquids.
Microbiological and sensory quality of Farmers cheese produced from milk with different somatic cells count
Authors: Ivanov G Y , Bilgucu E , Dimitrova M R , Ivanova I V 
Published: February 2021

Abstract
The aim of the present study was to evaluate the effect of somatic cell count SCC of raw milk on the microbiological and sensory characteristics during ageing and storage of Farmers cheese. Test cheese samples were produced from three batches of cow’s milk with low (batches L), medium (batches M) and high (batches H) SCC, respectively. Regardless of the differences in SCC, the physicochemical and microbiological characteristics of the three batches were similar. The SCC values in the raw milk had no significant influence on the content of the main components, active acidity and lactic acid concentration in the cheeses produced. In the cheeses made from milks with SCCs exceeding 500,000 cells/ml, the growth of Lactobacillus delbrueckii subsp. bulgaricus was slower compared to the other test samples. The changes in the Streptococcus thermophilus count in the cheese test samples showed trends similar to those established with L. delbrueckii subsp. bulgaricus. Lower sensitivity of S. thermophilus to the inhibiting factors in the milks with a high SCC in comparison with L. delbrueckii subsp. bulgaricus was established. The increase in the SCC values in the raw cow’s milk over 500,000 cells/ml had a negative effect on the organoleptic characteristics and shelf life of the Farmers cheese made from that milk.
The usage of the whole grain spelt flour in the cracker’s technology
Authors: Iorgachova  , Makarova O , Khvostenko K 
Published: February 2021

Abstract
Nowadays there has been a revival of interest in ancient crops, such as spelt wheat, which differs from modern varieties of wheat with more balanced chemical content. The effect full replacement of modern wheat flour with whole grain spelt flour on the cracker’s quality was studied. Addition of the spelt flour leads to a high sensory characteristics formation of the product. Ancient wheat flour based samples characterized with more rich color and more intense taste and aroma. The usage of spelt flour increased the product’s ability to water absorption (145 %), acidity (2.0 degree), which are in the accordance with standard requirements.
The results have shown the positive effect on the nutritional value of the final product. The highest protein content (16.44 g/100 g) was obtained for the enriched samples, there were also an increase in micronutrients content ’ Fe (by 27.8 %), K (by 22.9 %), B5 (by 83.6 %). In vivo studies have proven that consumption of the products based on whole grain spelt flour effectively prevented the development of inflammation and dysbiosis processes. Obtained results indicate the effectiveness of full replacement modern wheat flour with whole grain spelt flour for the cracker’s with high nutritional value production.
Structural effects of selected hydrocolloids on Ca (II)-alginate beads containing hydrosol from Rosa damascena Mill
Authors: Petrova I , Petkova N , Slavchev Al , Petrova T 
Published: February 2021

Abstract
Alginates are suitable for the encapsulation of a great variety of biomolecules. Recent trends include encapsulation of plant extracts or macromolecules in alginate gel to enhance their health and functional properties when they are applied in food matrix or pharmaceutical products. The rose hydrosol is produced by the distillation of petals of (Rosa damascena Mill.). This product is popular in cosmetics also it is used as a food additive in some Eastern country. The aim of this study was to investigate the chemical composition, antioxidant potential of rose hydrosol and to evaluate the influence of different hydrocolloids on the structural-mechanical properties of Ca (II)-alginate beads with rose hydrosol. The alginate microspheres were formed with different amounts of sodium alginate (2-4%), sucrose, rose hydrosol and selected hydrocolloids, as neutral polysaccharides (inulin and guar gum) and anionic heteropolysacchides (pectin, K-carrageenan, xanthan). The addition of inulin in the concentration 3% and 6% resulted in the increase of the rupture force by 34% and led to improvement in plasticizing effect. The additional complete characterization of the beads with rose hydrosol was performed by Fourier-transform infrared spectroscopy, assigning the characteristic bands to each individual component. In this study, the obtained information for structure-mechanical properties allows the design of Ca (II)-alginate systems enriched with dietary fibers and rose hydrosol, with an acceptable sensory profile for future application in foods.
Chemical composition of Bulgarian white oregano (Origanum heracleoticum L.) essential oils
Authors: Baycheva S K , Dobreva K Z 
Published: February 2021

Abstract
The content and composition of essential oils obtained from wild and cultivated Bulgarian white oregano (Origanum Heracleoticum L.) were studied. Herb, inflorescences and leaves (2017 and 2018 harvest years) of wild oregano and leaves (2018 harvest year) of cultivated white oregano were examined. The influence of technological parameters on the yield of essential oil is studied. Content of the essential oils varies from 4,77% to 5,09% for the wild oregano and 5,74% for the cultivated. Aromatic compounds are in the highest amounts in all oils (64,63 – 86,16%). The main compounds (over 3%) in the wild white oregano essential oils were: carvacrol (57,52 – 75,29%), p-cymene (7,79 – 19,10%) and γ-terpinene (4,95 – 11,26%). The main compounds (over 3%) in the cultivated white oregano oil were: carvacrol (45,09%), thymol (12,06%), p-cymene (7,39%), γ-terpinene (5,20%) and thymol methyl ether (3,00%). The results supported the assumption that the studied overground parts of the Bulgarian white oregano are rich in essential oil containing the valuable aromatic compounds carvacrol and thymol, which are the reason for its properties.
Microbiological screening of tobacco raw materials for rolling of cigarettes
Authors: Hristeva T H , Nikolov N P , Nikolova V V , Peeva S T 
Published: February 2021

Abstract
In the modern market of tobacco products worldwide, there is a trend towards increased consumption and trade in cut tobacco for manual rolling of cigarettes (RYO tobacco), including and from unregulated producers. This hides additional risks for the health of the consumers due to the possibility to use low-quality and uncontrolled raw materials, including and with increased presence of pathogenic and conditionally pathogenic microorganisms.
The aim of the study was to determine the total amount of heterotrophic bacteria (microbial count), the amount of microscopic fungi and the most common species in the raw material for tobacco RYO, distributed on the Bulgarian market.
The microbiological analyzes were performed by classical methods accepted in sanitary microbiology. In all samples, spores of the genus Bacillus showed mass development, and according to the macro-morphological characteristics of the colonies, the predominant species can be attributed to B. cereus. The detected amounts of microscopic fungi in the tested tobacco mixtures were significant at strong presence of species of the genus Aspergillus, over 85.48%. Macroscopically, species were defined as A. flavus (41.94%), A. niger (27.42%) and A. fumigatum (16.13%). The relative share of species of the genus Penicillium was 9.68% and of species of the genus Mucor -4.84%. The studied tobacco raw material for manual rolling of cigarettes had significant contamination by microorganisms that had the rank of pathogens. Quantitative microbial assessment suggests a potential health risk for consumers.
Cut surface of Bulgarian white brined cheese evaluation by image analysis in HSI color space
Authors: Bosakova-Ardenska A , Andreeva H , Danev A , Panayotov P , Boyanova P 
Published: February 2021

Abstract
This paper presents a research over possibilities to evaluate a cut surface of white brined cheese by images analysis. Samples from seven trademarks of Bulgarian white cheese in brine are evaluated by experts and their cut surfaces are captured with digital camera. A Java application for color images processing in HSI color space is developed. The application executes multilevel thresholding and produces grayscale images with four colors – white, black, light gray and dark gray. The images of all tested cheese samples are processed with this application and there are calculated ratios of pixels with the same color to all pixels in the processed images (Kdiv for white, black, light gray and dark gray colors). The cut surfaces of cheese samples are evaluated by experts and it is performed a correlation analysis between experts’ estimation and the coefficients Kdiv. The results show that there are a significant correlation between experts’ estimation and the pixels with dark gray color (their coefficient Kdiv) in the processed images.
Physical and sensory characteristics of edible foams obtained with nitrous oxide
Authors: Stankov S S , Fidan H N , Hristov T G , Nikovska K N 
Published: February 2021

Abstract
The aim of the present study was to determine the physical and sensory characteristics of edible foams obtained with nitrous oxide. The recipe compositions of foams with the participation of yogurt, milk cream and fruit puree have been used. The edible foams, also called “espums” were obtained with two fruit puree concentrations -15 and 25% of the liquid’s total mass. The foaming capacity (FC) and foam stabilizing (FS) properties of the products were determined by applying the “Syphon” method. The foaming capacity was highest for the control sample (252.00±7.52%), followed by the foams with 15% persimmon puree (220.00±4.09%). The foam’s lowest foaming capacity values were obtained for the foam with chokeberry puree (180.00±2.19%). The foam stability was determined by the coefficient of foam stabilization, which was determined to be highest (100±9.55%) for the sample with 15% mango puree and lowest for the foam sample obtained with 25% physalis puree (95.77±0.24%). The sensory analysis revealed that the edible foam with 25% mango puree participation resulted in better sensory properties.
New ready-made mixture for biscuits enriched with subtropical fruit powder lucuma
Authors: Durakova A G , Vasileva A L , Slavov A M , Choroleeva K B 
Published: February 2021

Abstract
The consumption of healthy food will always be topical since the intake of unhealthy food has an important impact on a person’s energy resources, their state of mind and weight. This served as an impetus for the present study, namely the preparation of a new ready-made mixture for biscuits enriched with bioactive Lucuma fruit powder. We analysed the antioxidant capacity of the product via four different methods DPPH, ABTS, FRAP and CUPRAC, expressed as mM TE/g powder (2.31±0.53; 9.89±0.29; 8.08±0.51; 24.15±1.13, respectively). The essential objective of this study is to obtain experimental data on adsorption and desorption. We evaluated the sorption isotherms for both processes using the static gravimetric method for the temperatures of 10°C, 25°C and 40°C and relative humidity within the 0.11 -0.90 range. Our results showed that the sorption capacity decreases with the increase in temperature under the conditions of constant water activity. The obtained isotherms were described with four different mathematical models – modified Chung–Pfost, modified Oswin, modified Halsey and modified Henderson. According to our calculations, the modified Halsey model could be recommended for a satisfactory description of the sorption isotherms of the new biscuit mixture. The monolayer moisture content of each temperature was calculated using the Brunauer-Emmett-Teller (BET) equation for adsorption and desorption.
Online education and monitoring of quality indicators of e-learning use
Authors: Kovalenko O E , Cardoso L M , Kupriyanov O , Bondarenko T S 
Published: February 2021

Abstract
This article analyses the results of the proposed approach to quality assessment of the use of online courses in the system of Ukrainian Engineering Pedagogics Academy e-learning and to assess its effectiveness in solving the problem of improving the quality of education. The courses were inspected after the Spring 2020 semester, according to the following criteria: activity of the process participants; interactivity of the process when using an online course; the intensity of the process by the elements of a course; dynamics of students’ educational achievements and management of the process of using an online course. This article shows that without painstaking daily systematic work regarding supporting the use of each online course, one should not hope for the effective impact of this form of studying. This should be done in every educational institution because the COVID-19 pandemic is not over and a significant part of educational institutions will spend the 2020/2021 academic year under the strict quarantine.
A Concept of Visual Programming Tool for Learning VHDL
Authors: Ivanova Aneliya 
Published: February 2021

Abstract
Due to the COVID-19 pandemic, distance education starts playing a crucial role in higher education and the need for development of educational tools, helping the students learn better at home cannot be ignored. Teaching programming languages online is a complicated task and when the course subject is programmable logic design through Hardware Description Languages (HDLs), online teaching becomes a complex challenge. In this paper is presented a concept of a training environment that uses the visual programing technique to help the students create VHDL models of various digital devices. The students construct VHDL models by combining simple visual objects while the environment is providing guidance in real time and is preventing a wrong match of VHDL operators and signals. The strategy for building a model of a compex digital circuit by moving and connecting visual objects will help the students with visual kinaesthetic learning style to internalize the concept and the structure of the VHDL model. The training environment will benefit mostly the students, learning in distance mode, but it is also useful for face-to-face students, who find it difficult to assimilate the specifics of VHDL modelling.
Laboratory complex for training and research of PV-technologies
Authors: Zaerov Eldar , Simionov Radoslav , Seymenliyski Kamen , Letskovska Silviya 
Published: February 2021

Abstract
In recent years, in the EU and, in particular, in Bulgaria, there has been a lack of efficiency in the construction of high-capacity photovoltaic power plants concentrated in areas with low population density. This has sparked a trend towards small PV systems close to consumers. The focus is on the generation and distribution of electricity through the construction of small rooftop PV power plants. The decentralization process for the construction of such stations is the most advanced. In connection with the stimulation of the construction of small photovoltaic power plants as decentralized sources of electricity and their proper technological construction, it is necessary to build an effective learning environment for the training of specialists in practice. The purpose of this article is to present some of the results obtained in conducting laboratory tests conducted jointly with students in the process of their studying.