UNIVERSITY OF FOOD TECHNOLOGIES - PLOVDIV

Logo



THEMATIC AREAS



Relationship of Somatic Cell Counts and Quality of Milk

Milk is important source of essential nutrients for many people in the world. Chemical composition of milk is substantially affected by many factors, such as species, breed, stage of lactation, animal’s age, health, feeding regime, and season. Somatic cells are a component naturally present in milk and microbial parameter "Somatic Cell

Authors: Tatyana Balabanova

Determination of the permissible amount of honey and bee pollen in yoghurt by data fusion

Предложен е метод за определяне на допустимите количества пчелен мед и пчелен прашец, добавени в кисело мляко, като са използвани данни за титруемата и активна киселинност; цветови и спектрални характеристики; електропроводимост и ултразвукови измервания. Използван е метод на последователно подобряващи се оценки, чрез които е намален броят на получаваните комбинации от признаци. Посредством Факторен анализ са определени тегловните коефициенти на различните количества пчелен мед и пчелен прашец, добавени към млякото. Селектирани са предсказващи модели, които описват с достатъчна точност връзката, между количеството пчелен мед и пчелен прашец в млякото и тегловните им коефициенти. Чрез минимума на функцията на получените модели, са определени допустимите количества от пчелен мед и пчелен прашец в киселото мляко, при които не се нарушават физико-химичните и органолептичните му свойства. Допустимите количества в кисело мляко за пчелен мед са 7,4%, а за пчелен прашец – 0,42 %.

Authors: Milen Dimov

Effect of stage of lactation and somatic cell count in ewe`s milk

The aim of the present study was to establish the change of the chemical and microbiological parameters on the composition of ewe`s milk, obtained from the Pleven Black-head breed of sheep during the different stages of lactation. It was found that the chemical parameters of ewe milk vary widely due to the way of raised and fed of animals. The obtain results describe a slightly increase in the values of the titratable acidity from 19 to 24°T and decrease in the values of dry matter (19.216.6%), milk fat (8.06.2%), protein (5.84.9%) content during the stage of lactation. The microbiological analysis shows that the somatic cell count and total number of microorganisms during lactation progressively decreases, as a resulting of high hygiene of the raised, nutrition of animals, environment and health status. Moreover, changes in the composition of ewe milk are directly dependent between transitions from stable to stable-pasture and pasture feeding system stages during lactation period.

Authors: Татяна Балабанова и Михаела Иванова

EFFECT OF RIPENING TEMPERATURE ON THE FERMENTATION PROCESS IN KASHKAVAL CHEESE

Целта на настоящото изследване е да оцени влиянието на температурните режими на зреене върху млечнокиселият процес в кашкавал от краве мляко. Процеса на зреене на опитните проби кашкавал е проведен при три различни температурни режима 9,0±1,0 °С, 11,0±1,0 °С и 13,0±1,0 °С в продължение на 60 дни. Проследени са измененията в рН и титруемата киселинност на кашкавала, както и растежа на млечнокиселата микрофлора в процеса на зреене. Установено е, че зреенето на кашкавала при температури под 10 оС е съпроводено с инхибиране на млечнокиселия процес. Причина за това е забавеното развитие на млечнокиселата микрофлора на кашкавала, която е съставена предимно от термофилни микроорганизми. Повишаването на температурата на зреене над 10 оС способства за по-интензивно развитие на млечнокиселата микрофлора в кашкавала, което е съпроводено и с по-интензивен млечнокисел процес.

Authors: A. Маркова, Г. Иванов

MICROSTRUCTURE OF CAW MILK KASHKAVAL CHEESE STORED AT DIFFERENT TEMPERATURES

Целта на настоящото изследване е да оцени влиянието на температурните режими на хладилно съхранение върху микроструктурата на кашкавал от краве мляко. Опитните проби кашкавал са съхранявани в продължение на дванадесет месеца при четири различни температурни режима – в охладено състояние при 4,0±1,0 °С, в охладено състояние при 1,0±1,0 °С, в подмразено състояние при -7,5±0,5 оС и в замразено състояние при -18,0±1,0 °С. Проследени са измененията в микроструктурата на кашкавала, посредством изготвянето на микроскопски препарати на 3-ти, 6-ти, 9-ти и 12-ти месец от процеса на хладилно съхранение. Установено е, че до 6-тия месец от съхранението микроструктурата на пробите кашкавал, съхранявани в подмразено състояние не се различава съществено от тази на пробите, съхранявани в охладено състояние. В края на процеса на съхранение в подмразените проби кашкавал се наблюдават по-големи разкъсвания в сиренната матрица в сравнение с охладения кашкавал. Най-съществени изменения в микроструктурата съпроводени със значителни разкъсвания на протеиновата матрица, се наблюдават при пробите кашкавал съхранявани в замразено състояние.

Authors: Г. Иванов, A. Маркова

BIOGENIC AMINES IN DAIRY PRODUCTS

Биогенните амини са биологичноактивни нискомолекулни органични съединения, съдържащи в молекулите си една или повече амино групи. Те се получават при декарбоксилирането на повечето аминокиселини под действие на аминокиселинни декарбоксилази. Често се откриват във ферментирали храни и напитки в т.ч. и в голяма част от млечните продукти. В ниски концентрации биогенните амини са от съществено значение за много физиологични функции в човешкия организъм, но постъпили в големи количества, тези съединения могат да причинят токсикологични проблеми. Съдържащите се биогенни амини в храните предизвикват огромен интерес не само поради тяхната токсичност, но и поради възможността да се използват като показатели за развала. Това определя необходимостта от контрола на съдържанието им в храните. Заедно с рибата и виното, сиренето е един от хранителните продукти, съдържащ високи нива на биогенни амини. Натрупването на биогенни амини в сиренето може да бъде повлияно на първо място от степента на микробна обсемененост на суровото мляко, хигиена на производството, използваните стартерни култури, условията на околната среда, температурата и продължителността на зреене. Най-често срещаните биогенни амини в сирената са тирамин, хистамин, кадаверин, путресцин и β-фенилетиламин.

Authors: Г. Иванов

Еffect of blueberries addition during beer maturation on yeast metabolism

In recent years, there has been a significant interest in beverages with increased biological value, such as beer with blueberries. In this study, blueberries were added at the beginning of maturation of beer with an initial extract of 12, 14 and 16 ºP. The effect of blueberries addition on yeast metabolism was investigated as concentration of ethanol, higher alcohols, esters, aldehydes, and vicinal diketones in the final beer were measured and compared to control samples without blueberries. The results obtained showed that blueberries addition affected yeast metabolism differently depending on yeast by-product type and wort original gravity.

Authors: Rada Georgieva, Petar Nedyalkov, Vesela Shopska, Maria Kaneva

Sensory profile of fruit juices

The objective of this research was to compare the dynamic sensory profile of fruit juices. Sensory attributes of nine fruit juices were compared using a trained sensory panel. The panelist used the sensory spectrum method and the multiple time‐intensity analysis to evaluate attributes of the juices at 24ºC. The aroma attributes were evaluated first, followed by the color and taste attributes. The rest of the assessed attribute were aftertastes and clarity. The nine blends were presented to each subject in the order based on a balanced incomplete block design to prevent any biasing effect.

Authors: Marin Georgiev, Aneta Popova, Dasha Mihaylova

Application of functional additives in ice cream production

A priority for the frozen dessert industry is the development of products with health benefits, containing natural biological substances, probiotic strains of lactic acid bacteria and others, ensuring the health and quality of life of consumers. The enrichment of ice cream compositions with biologically active substances leads to possible health benefits and improvement of the physico-chemical profile of the ice cream mixture. The current review article is focused on the new trends in ice cream production by applying functional additives: Spirulina platensis, cranberry extract (Vaccinium vitis-idaea L.) and probiotic strains of lactic acid bacteria.

Authors: Petya Boyanova, Peter Panayotov, Iliana Milkova-Tomova, Dragomira Buhalova, Dilyana Gradinarska

Microbiological problems in brewing – a review

Beer is the oldest fermented beverage, but its microbiology has been studied since XІX century. Beer microbiology has two main purposes: control of culture yeast and control of spoilage microorganisms. Although beer is a relatively stable product, spoilage microorganisms such as: wild yeasts, moulds, lactic acid bacteria, acetic acid bacteria and other bacteria like Zymomonas, Enterobacteriaceae, Megasphaera, Pectinatus, Selenomonas, Propionispira can cause problems with beer quality. In this paper, microbiological problems in brewing from raw materials through every stage of beer production till final product will be discussed.

Authors: Vesela Shopska - UFT-Plovdiv


Study on the spread of nematode larvae in fishes, marketed in Bulgaria

Authors: проф. д-р Йордан Гогов, гл.ас. д-р Гергана Крумова


Effects of a candidate - probiotic Lactobacillus fermentum on the growth and biofilm formation of Gram-positive and Gram-negative bacteria

Antimicrobial activity of lactic acid bacteria (LAB) is a widely accepted criterion for a probiotics’ pre-selection. With this aim a group of lactobacilli, isolated from different habitats, were assessed. Lactobacillus fermentum FH3 (the new genus - Limosilactobacillus fermentum), with a human origin, was estimated as a promising candidate. The strain FH3 exhibited a broad spectrum of activity against different pathogens. The active metabolites produced in MRS broth (pH 6.5) and cell-derived fragments (lysates) showed the capacity to influence growth and biofilms of Escherichia coli 420, Pseudomonas aeruginosae Pa-01, Bacillus subtillis 168 and Staphylococcus aureus 29213. Different inhibitory effects of tested acid (aCFS) and neutralised (nCFS) cell-free supernatants were in vitro observed. The growth of Gram (-) cultures was significantly inhibited, until 50 h cultivation in the presence of 10% v/v aCFS. However, stronger effects showed the LAB lysates. A strain or species – specific suppression on the pathogenic biofilms formation was observed. All tested samples strongly inhibited the biofilms of Gram (+) and Gram (-) pathogens, except the biofilms of S. aureus. Controversially of the growth effect, it was stimulated by lysates. The antagonistic activity of L. fermentum FH3 is due to the produced during the fermentation organic acids, hydrogen peroxide and probably other peptide/proteinaceus bacteriocin-like substances, derived from cells lysates. Further characterization, however is needed and it is still in progress. Acknowledgements: The authors are grateful to Bulgarian Scientific fund for the financial support – project KP06 OPR 03/16 and to National Program “Young Scientists and Post-Doctoral fellowship”-Ministry of Education and Science.

Authors: Tsvetelina Paunova-Krasteva, Lili Dobreva, Petia Dimitrova, Dayana Borisova, Svetla Danova and Stoyanka Stoitsova, Department of General microbiology, The Stephan Angeloff Institute of Microbiology, Bulgarian Academy of Science, 26, Acad. G. Bontchev str.


Amperometric detection of nitrite, sulfite and ascorbic acid at glassy carbon electrode modified with cerium hexacyanoferrate

Nowadays, research on electrochemical sensors attracts lots of current interest because of their broad applications in food industry, ecology, medicine, etc. In food quality control electrochemical sensor systems provide the opportunity for an accurate, highly sensitive, selective, cost-effective and susceptible to automation analysis of various food components as well as toxic compounds. In this regard, cerium hexacyanoferrate was electrochemically deposited onto a glassy carbon (GC) electrode applying consecutive cyclic voltammetry in the potential range from –0.2 to 0.8 V (vs. Ag/AgCl, 3 M KCl). The electrocatalytic properties of the modified electrode CeHCF/GC were evaluated with regards to electrooxidation of nitrite, sulfite and ascorbic acid. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results showed fast response, good stability and outstanding electrocatalytic activity of CeHCF/GC for the detection of these substances. The data obtained from the quantitative detection measurements offer potential application of the developed new electrocatalys as a sensing element in sensor devices for accurate monitoring of the aforementioned analytes.

Authors: Yanna Lazarova, Totka Dodevska and Ivan Shterev

Phenol biodegradation by the strain Bradyrhizobium japonicum 273 under the condition of constant electric field

The present study considers the effect of constant electric field on the phenol biodegradation potential of the strain Bradyrhizobium japonicum 273 in aqueous media. The significant effects are observed the constant electric field applied enhances the specific growth rate of the bacteria studied at a specified anode potential, i.e. 0,6 V; 0,7 V and 0,8 V versus the standard hydrogen electrode (S.H.E). In processes with a culture without application of electricity, the amount of destroyed phenol is 0,86 g. Compared to a processes under the condition of constant electric field at a 0,6 V/S.H.E. the amount of destroyed phenol is 1 g; at a 0,7 V/S.H.E. - 2,2 g; at a 0,8 V/S.H.E. - 4,24 g. The amount of phenol destroyed and the biodegradation rate are maximum at the 0,8 V/S.H.E. The amount of phenol destroyed is fifth times higher than that in the control experiment. Keywords: biodegradation, phenol, Bradyrhizobium japonicum 273 strain, constant electric field ACKNOWLEDGMENTS This work was supported under project DN 17/4. The authors would like to thank the National Science Fund, Ministry of Education and Science of the Republic of Bulgaria

Authors: E. Vasileva, Ts. Parvanova-Mancheva, V. Beschkov

Enzymes related to the processes of wastewater treatment from phenolic pollutants

When phenol is metabolized by the Pseudomonas putida strain, catechol appears as an intermediate. The site of cleavage of its aromatic ring is determined by the type of enzymes induced by the primary substrate (phenol). Upon synthesis of 1,2-oxygenase, the catechol ring opens at the ortho site. In the synthesis of 2,3-oxygenase, its cleavage takes place at the meta-site. In the experiments performed in our laboratory, mainly 1,2-oxygenase with significant enzymatic activity of 0.992 U / mg protein was synthesized. The enzymatic activity of 2,3-oxygenase is 0.004 U / mg protein. Key words: Pseudomonas putida, enzymes, metabolic pathway, catechol ACKNOWLEDGMENTS This work was supported under project DN 17/4. The authors would like to thank the National Science Fund, Ministry of Education and Science of the Republic of Bulgaria

Authors: Tsvetomila I. Parvanova-Mancheva -Institute of Chemical Engineering Sofia





Extrusion of wheat semolina and cocoa shells

Extrusion of wheat semolina and milled cocoa shells using a single screw extruder Brabender 20DN was carried out. Full factorial experiment 23 was used to investigate the effect of the quantity of cocoa shells, moisture of the material and temperature of the matrix on the density and expansion index of extrudates. Feed screw speed and screw speed were fixed at 30 and 200 rpm, respectively. Compression ratio of the screw was 4:1. Expansion index values range between 2,0 and 3,36 and a density between 0,099 and 0,251 g/cm3. The increase in moisture content and quantity of cocoa shells leads to a decrease expansion index, while density of extrudates an increase.

Authors: Нешо Тошков, Венцислав Ненов, Божидар Бозаджиев, Найден Делчев, Ерик Вълов

Investigation of concentration and retention factors during ultrafiltration of goat’s milk

This experimental work aimed to investigate the concentration and retention (selectivity) factors during ultrafiltration of goat’s milk with UF25-PAN polyacrylnitrile membrane. They were calculated on the basis of dry matter, protein, fat and mineral contents in retentates and permeate at volume reduction ratios 2 and 3. The results showed that the increase in the volume reduction ratio led to an increase in the concentration factors of the above mentioned components and in the retention factor of mineral substances. There was no statistical significant difference of the selectivity according to the proteins when volume reduction ratio increased.

Authors: Siyka Kodinova, Mariya Dushkova

Authors: Igor Yarovyi - ONAFT Odesa, Oleksandr Zykov - ONAFT Odesa

An Analysis of Specific Processes of the Avian Waste Pyrolysis

Authors: Gheorghe Lazaroiu, Lucian Mihaescu, Viorel Berbece

An alternative strategy for the sustainable production of biodiesel from Dairy Waste Scum

The gradual depletion of the world's oil reserves and the increased pollution of the environment with greenhouse gas emissions leads to the search for alternative sources of petroleum fuels. These fuels, on the one hand, must meet the amount of growing energy demand and, on the other hand, reduce greenhouse gas emissions. Biofuels, especially biodiesel, are a fuel that has great potential to replace petro-diesel. Biodiesel is renewable, non-toxic and biodegradable. It is a carbon neutral fuel. The biodiesel combustion releases as much carbon dioxide as was taken from the atmosphere during photosynthesis and plant growth. the most common raw materials for biodiesel production worldwide are vegetable oil, animal fats, waste cooking oil and micro algal oil. etc. Due to the ongoing humanitarian crises in various parts of the world, the issue of obtaining biodiesel from unconventional raw materials is becoming more and more important. This study aimed to provide an alternative strategy sustainable biodiesel production from combination on the dairy waste with other oil sources. The biodiesel from dairy waste scum oil is a possible analogue for petro-diesel. Milk in various forms is present on the table of many people. There are number of dairy industries producing drinking milk and associated products such as cheese, yogurt, milk powder, ice-cream etc. Large dairy industries productions large quantity of dairy waste scum. In this paper one conceivable approach to combination over this waste milk scum with other oil sources in to biodiesel and use it as an untraditional fuel is presented.

Authors: Desislava Nikolova,Boyan Ivanov,Yunzile Dzhelil



Application of image processing using NI LabVIEW for mold distribution analysis in blue cheese

The NI LabVIEW is a software for real-time data processing and it is widely used for process control in industry. It has a lot of additional libraries and modules which extends its functions, and support its application in many different areas. Vision Builder and Vision Assistant are modules in NI LabVIEW which support image acquisition and processing. These modules are used for the purpose of current research in order to analyze mold distribution in blue cheese. Eight trademarks of blue cheese are used for comparative analysis of mold distribution. Every sample is cut with special cheese slicer in order to evaluate its mold distribution. The samples are captured with digital camera and images are processed in NI LabVIEW environment. Coefficient of mold (ratio of pixels with mold to all pixels in cut surface of cheese) is calculated for nein regions of interest on every picture. This coefficient is used for statistical analysis of mold distribution. It is observed that cheese which have low quantity of mold are presented with non-even mold distribution and cheese which have high quantity of mold are presented with almost even mold distribution.

Authors: Vladimira Ganchovska, Atanaska Bosakova-Ardenska,






Professional education- between pedagogy and psychoanalisis

The material presents the implementation of psychoanalytic approach in teaching university students to acquire professional pedagogical qualification and skills. Some aspects of theoretical psychoanalytical knowledge arepresented, to facilitate the communication between the participants in the educational process. Two case studies are included to illustrate this educational process of professional competence.