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Background The bio-preservation of food products using various natural ingredients and metabolites from various types of beneficial microorganisms released during targeted fermentation is a method that simultaneously has a preservative effect on the food product and provides a model of its composition in order to ensure its functional and health properties. This double effect can be achieved by incorporating ingredients with proven preservative and functional effects into the food product, such as essential oils from various plant species and probiotic bacteria. The aim of the present research was to study the synergistic effect of selected probiotic lactic acid bacteria (LAB) and essential oils with high antimicrobial activity against pathogenic and spoilage microorganisms for the bio-preservation of chocolate mousse food emulsion. Methods The susceptibility of the selected probiotic strain Lactobacillus plantarum D2 to different concentrations of the selected lemon or grapefruit essential oil was examined using the disc-diffusion method. Nine chocolate mousse variants were prepared with the inclusion of free or immobilized cells of the probiotic strain L. plantarum D2 and/or lemon or grapefruit zest essential oils. The chocolate mousse variants were stored for 20 days in refrigerated conditions, and changes in the concentration of viable lactobacilli cells, the pH and the microbiological purity were monitored in accordance with standard requirements by taking samples on the 0th, 5th, 10th, 15th, and 20th days of storage. An organoleptic evaluation of the chocolate variants was performed on the 0th day. Results Concentrations of up to 1% lemon or grapefruit essential oil did not affect the growth of the probiotic strain L. plantarum D2, which revealed opportunities for their joint application for the bio-preservation of food emulsions. The obtained chocolate mousse variants were characterized by preserved organoleptic characteristics and microbiological safety. Free or immobilized probiotic L. plantarum D2 cells applied alone or in combination with lemon or grapefruit essential oils provided bio-preservation of the food emulsions, maintaining a high concentration of viable cells (106-107 cfu/g) during storage under refrigerated conditions for 20 days. Conclusions The combined application of free or immobilized probiotic LAB and lemon or grapefruit essential oils resulted in better bio-preservation results than in the use of probiotic LAB or essential oils alone, thus suggesting a synergistic effect between the two bio-preservative agents. Moreover, the obtained chocolate mousse emulsions can be classified as functional foods and the chocolate mousse food matrix can successfully be used as a vehicle for delivery of probiotic LAB to a wide range of food consumers. The obtained results and the developed successful bio-preservation strategy for the production of chocolate mousse food emulsions would provide grounds for the future selection of other probiotic lactobacilli strains, essential oils and synergistic combinations of them for the development of successful bio-preservation strategies for other types of food and beverage products.

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 dynamic results the decrease in the fermentation temperature from 10 °C to 5 °C at pitching rate of 109 Colony Forming Units cm−3 ( CFU cm−3 ) led to significantly reduced concentrations of ethanol and secondary metabolites in beer. The temperature decrease from 10 °C to 7 °C at pitching rate of 107 CFU cm−3 resulted in a decrease in the alcohol concentration and increase in all the secondary metabolite concentrations except for the vicinal diketones concentration. Data show that yeast biomass does not grow at 5 °C and at inoculum concentration of 107 CFU cm−3, which makes fermentation impossible. Fermentation kinetics using Monod's model supplemented with product inhibition was also investigated. Up to 1.7 % of alcohol accumulates in the beer in some of the variants within 7 days. At low fermentation temperatures, yeast biomass utilizes part of the substrate to maintain its vital activity under stress fermentation conditions, which leads to a reduction in the amount of alcohol synthesized. The synthesis and reduction of the secondary metabolites was delayed compared to conventional beer fermentation. The sensory evaluation of the beers produced showed that the most appealing beer was the one produced at 10 °C and pitching rate of 109 CFU cm−3.

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 the present study the main brewing characteristics, the phenolic profile and the antioxidant potential of 20 malt types used in craft breweries in Bulgaria have been examined. The main brewing characteristics have been determined by the standardized methods of the European Brewing Convention. Malt phenolic content was determined by two methods, and antioxidant potential by five different methods. Based on a statistical factor analysis performed by the principal component analysis, it was confirmed that there was a relationship between malt color and phenolic compounds content. The principal component analysis confirmed that there was a link between the content of the Maillard reaction products and malt biological activity. Malts with the highest degree of heat treatment were characterized by the highest antioxidant activity, which was due to the content of Maillard reaction products with antioxidant capacity.

Pediococci are lactic acid bacteria widely used as starter cultures in the food industry, which produce lactic acid and bacteriocins (pediocins) possessing significant antilisterial potential. This research aimed to investigate the antimicrobial activity of three Pediococcus strains (Pediococcus pentosaceus, Pediococcus acidilactici and Pediococcus damnosus) against three Listeria strains (Listeria monocytogenes, Listeria innocua and Listeria ivanovii) to determine the growth characteristics and kinetic parameters during the process of co-cultivation at 37 ± 1°C. The results demonstrated that P. pentosaceus possessed a bacteriostatic effect on L. monocytogenes, but a bactericidal effect on L. innocua and L. ivanovii, and on the 60-th h no viable cells of both pathogens were detected. P. acidilactici demonstrated a strong bactericidal effect on the three Listeria strains, as L. monocytogenes was completely inhibited on the 48-th h and L. innocua and L. ivanovii were inhibited on the 60-th h of co-cultivation. In contrast, P. damnosus showed only a bacteriostatic effect on the three pathogens tested. Therefore, the strains P. pentosaceus and P. acidilactici can be successfully applied in the food industry as biopreservatives and as means to improve the food safety by inhibition of Listeria spp., which are among the most common pathogens in food products of animal origin.

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 lactic acid were used to model the growth kinetics in the present work. The rate constant of adaptation of the studied strains to the used nutrient medium and the induction period were also determined. The kinetics of lactic acid synthesis was determined according to the Weibull model.

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 (measured by DPPH, FRAP, CUPRAC, ABTS, and ORAC) of wort, produced by Vienna, Melanoidin, Caramel pils and Special X malt or mixture of them. The results obtained were used for the modelling and optimisation of malt mixture that can be used for the production of functional beverages. Optimisation was made on the basis of wort extract, total phenolic compounds (measured by Folin–Ciocalteu method), and antioxidant activity, measured by DPPH, FRAP, and ORAC methods. Although optimised variants with high content of Special X malt showed highest antioxidant activity, they had an unpleasant taste and slow mash filtration rate. Therefore, the variant with 24.2% Vienna, 51.8% Melanoidin, 20% Caramel pils, and 4% Special X malts was chosen for the production of functional wort-based beverages.

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. Materials and methods. Wort was produced with 60% Pilsen malt, 20% Vienna malt and 20% Caramel Munich ІІ malt with and without the addition of 0.05% (v/v) grapefruit or tangerine essential oils. It was inoculated with the probiotic yeast strain Saccharomyces cerevisiae var. boulardii Y1. Fermentations were carried out at a constant temperature of 10°C for 5 days. The dynamics of the extract, the alcohol content and the concentration of viable cells were monitored daily. The total phenolic content, phenolic acid and flavonoid phenolic compounds were determined because of their antioxidant activity. The antioxidant activity was determined by radical scavenging assay (DPPH) and ferric reducing antioxidant power (FRAP). A descriptive organoleptic evaluation of the final beverages was performed. Results. The essential oils inhibited yeast growth to some extent at the beginning of the fermentation, even at a concentration of 0.05% (v/v), which resulted in lower alcohol content in the beverages with essential oil addition. Nevertheless, at the end of fermentation the concentration of viable cells was almost equal in all the beverages. Tangerine essential oil addition led to the highest content of phenolics, of which phenolic acids predominated. Therefore, the highest antioxidant activity of the beverage with tangerine essential oil can be ascribed to phenolic acids. The results of the sensorial evaluation also showed that the panel had preference towards the beverage with tangerine essential oil. Conclusion. The combination of essential oil and the probiotic yeast strain resulted in beverages with higher biological value than the beverages produced with the probiotic strain alone. The results obtained will be used for optimisation of process variables in the production of pilot-scale wort-based probiotic beverages with essential oil addition.

The phytochemical and biological properties of tangerine (Citrus reticulata L.), grapefruit (Citrus paradisi L.), lemon (Citrus lemon L.) and cinnamon (Cinnamomum zeylanicum Blume) essential oils were examined. The chemical composition of the essential oils determined using chromatography analysis revealed that D-limonene and cis-cinnamaldehyde were the main components. The antioxidant and antimicrobial activities of the essential oils have been studied by the DPPH radical-scavenging assay and the disc-diffusion method, respectively. All essential oils had antimicrobial activity against saprophytic (Bacillus subtilis, Penicillium chrysogenum, Fusarium moniliforme, Aspergillus niger, Aspergillus flavus, Saccharomyces cerevisiae) and pathogenic microorganisms (Escherichia coli, Salmonella abony, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans), with the highest inhibitory activity being observed in cinnamon oil, followed by grapefruit zest oil, tangerine zest oil and lemon zest oil; the MIC ranging from 6 to 60 ppm. In addition, they exhibited high antioxidant activity with the highest antioxidant activity being determined for the grapefruit zest essential oil, followed by the lemon zest essential oil, the tangerine zest essential oil and the cinnamon essential oil. The demonstrated promising results for the antioxidant and antimicrobial activity of the studied essential oils would give reason for their inclusion in the development of bio-preservation strategies for food emulsion preservation.

The effect of lavender (Lavandula angustifolia) and melissa (Melissa Officinalis) waste on preparation, characteristics and shelf life of bread was investigated. It was found that lavender and melissa waste, generated yearly in large amounts, were rich on polyphenols (especially rosmarinic acid) and aroma compounds, and exhibited high antioxidant and antimicrobial activity. The bread with 2.5% lavender waste was characterized with the highest loaf volume and loaf specific volume. The total dietary fiber increased three times and the polyphenols and flavonoids increased more than four times for breads with added 5% lavender and melissa waste, compared to control sample. The breads with 2.5% and 5% added lavender waste had increased shelf life (up to 96 h) compared to control, and no fungal or bacterial spoilage was observed during storage at 22 °C, 30 °C and 37 °C for four days. The sensory evaluation demonstrated that the consumers preferred mainly bread with 2.5% lavender waste.

Brewers' spent grains (BSG) form 85% of the waste products from the brewing process. BSG contain a number of substances with functional benefits and can be used for the production of new food types. The present publication considers the main characteristics of BSG derived from six malt types: light barley malt, Pilsner malt, wheat malt, Munich malt type II, Vienna malt and Carafa malt type III. The spent grain starch content, the degree of starch gelatinization, the phenolic compound content and the antioxidant capacity of the spent grains were examined. Based on the values of the latter three parameters, optimization of a malt mixture was performed, which guaranteed BSG with a maximum total phenolic compound value and maximum antioxidant capacity. It was found that the type and the conditions for malt production influenced the physicochemical composition of brewers' spent grains. Copyright © 2017 The Institute of Brewing & Distilling

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 alginate type and concentration, homogenization rate and the oil phase amount in the preparation of capsules rich in olive oil. It has been found that emulsions obtained with medium viscosity alginate were characterized by better stability. To establish the joint influence of the factors was used screening design experiment, the optimization features selected being temperature, centrifugal and microscopic stability. The optimal levels of the factors were established and they we applied for capsule preparation. The obtained capsules showed maximum stability and possibility to be used in dairy product manufacture.

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 (20.40%), β-linanool (14.35%), eugenol (10.55%), and L(-)-carvone (39.05%), whereas dill oil contained mostly d -limonene (21.11%) and α-phellandrene (22.68%). The essential oils exhibited strong antimicrobial activity against all test-microorganisms. The mayonnaise variants were kept refrigerated for 40 days and changes in pH, concentration of viable cells of lactobacilli, microbiological, and organoleptic characteristics were monitored. The pH decreased from 6.5 to 4.5 over the period of storage. The number of undesired microflora in mayonnaise preserved with lactobacilli and essential oils decreased significantly (0 after the 20th day) indicating their effectiveness as biological preservatives. The mayonnaise variants demonstrated pleasant organoleptic characteristics, thus meet customers’ requirements.

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 method which provides stability of the substance in the food product. The principles for implementing encapsulation of biologically active substances, especially natural oils, the matrices and the encapsulation methods are discussed in the present review. Data on the impact of key process parameters of encapsulation, the biological value of oils and the opportunities for application of the encapsulated systems in different groups of dairy products are presented.

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 effects, emulsified products containing water are often prone to microbial growth justifying thus the addition of preservatives such as parabens in their formulation. Safety concerns regarding some synthetic preservatives have stimulated the development of natural antimicrobial ingredients (namely from plant or microbial origin) for the preservation of food or cosmetic products. Besides direct addition of antimicrobial biomolecules, the addition of living bioprotective bacteria such as probiotic lactic acid bacteria (LAB) is a promising approach. Franco-Bulgarian ESCAPE project ambition is to identify synergistic combinations of such probiotic LAB and plant extracts for the preservation of food or cosmetic emulsions. The methodology and the relevant scientific questions (application of hurdle technology principles, selection of plant extracts not affecting LAB growth/viability and antimicrobial activity, distribution of LAB and antimicrobial metabolites in the different phases of emulsions, effect of LAB and plant extracts on emulsions stability…) to tackle this objective are presented and discussed.

The fermentation process is of key importance in beer production. During fermentation the organoleptic profile of beer is formed through the synthesis of alcohol and a number of secondary metabolites: esters, aldehydes, higher alcohols, and vicinal diketones. Their quantity and the ratio between the different groups of metabolites determine beer quality. The aim of this chapter is to present the main kinetic models describing the alcohol fermentation process and the accumulation of metabolites in beer production in two main areas: beer quality and control of the fermentation process. A critical analysis of the existing kinetic models for the fermentation process description, that is, yeast growth, ethanol and secondary metabolite production, and wort sugar consumption (substrate utilization), was made. Methods for process kinetic formalization were proposed in order to control the fermentation accurately with a view to beer quality optimization. The proposed studies were based on real experiments and data for key biochemical foundations of the alcohol fermentation process.

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 main components of the essential oil were limonene (85.22%), β-myrcene (4.3%), and α-pinene (1.29%). Regarding the DPPH radical scavenging ability, the zest essential oil showed higher activity than limonene. The antimicrobial activity of the essential oil against pathogenic [Staphylococcus aureus NBIMCC 3703, Salmonella sp. (clinical isolate), Pseudomonas aeruginosa NBIMCC 1390, Bacillus subtilis NBIMCC 1208, Escherichia coli NBIMCC 3702] microorganisms by disc-diffusion method was examined. Gram-positive bacteria were more sensitive to the oil (inhibition zones being between 9 and 12.5 mm) and the minimum inhibitory concentration was more than 600 ppm; Gram-negative bacteria were less sensitive. The obtained essential oil displayed promising results for its application as a biopreservative agent.

A comparative study of kinetic models to describe the dynamics of the fermentation process of culturing of a probiotic strain Lactobacillus delbrueckii ssp. bulgaricus B1 was performed. The models of Monod, Aiba, Tiessier, Hinshelwood and the equation of the logistic curve combined with the model of Ludeking-Piret were used. It has been found that the different models described the observed fermentation dynamics differently. The conducted comparative study demonstrated that the models of Monod and the equation of the logistic curve combined with the model of Ludeking-Piret were suitable for the description of the fermentation dynamics. The mathematical models showed no significant product and/or substrate inhibition. The culture developed with a low specific growth rate, but nevertheless it accumulated 1012-1013 viable cells. The substrate was absorbed primarily from cells in the stationary growth phase rather than cells in the exponential growth phase

In order for the beneficial effects of sourdough application in breadmaking to take place a proper selection of lactic acid bacteria species and strains, an appropriate technology and effective control of the purity and activity of the selected cultures. Four symbiotic starters for sourdough for the production of bread were developed and probated in a production laboratory using the selected strains Lactobacillus brevis LBRZ7, L. buchneri LBRZ6, L. plantarum X2, L. paracasei RN5, L. sanfranciscensis R and L. fermentum LBRH10 and the probiotic strain Propionibacterium freudenreichii ssp. shermanii NBIMCC 327. The starter sourdoughs that include Propionibacterium freudenreichii ssp. shermanii NBIMCC 327 had greater antimicrobial activity against saprophytic microorganisms: Bacillus subtilis, B. mesentericus, Aspergillus niger, Penicillium sp. and Rhizopus sp., but none of them inhibited the growth of bakery yeasts Saccharomyces cerevisiae. It was established that in order to prevent bacterial spoilage 10% of the selected starter sourdoughs had to be added in the breadmaking process, while for prevention of mold spoilage the necessary amount of starter sourdough had to be between 15% and 20%.The application of the developed starters for the production of wheat bread guarantees longer shelf life and no adverse alterations in the features of the final bread.

The ability of four Lactobacillus strains – Lactobacillus brevis LBRZ7 (isolated from fermented cabbage), Lactobacillus plantarum LBRZ12 (isolated from fermented cabbage), Lactobacillus fermentum LBRH9 (of human origin) and Lactobacillus casei ssp. rhamnosus LBRC11 (isolated from home-made cheese) – to grow in flour/water environment and to accumulate high concentrations of viable cells was examined. Two starters for sourdough were created for lab-scale production of wheat bread: a two-strain starter and a four-strain starter. Wheat bread with improved properties – greater loaf volume, enhanced flavour and softer and brighter crumb – was obtained from the 7% four-strain starter sourdough. The addition of sourdough in the production of wheat bread affected positively the technological and organoleptic characteristics of the final bread by inhibiting the growth of wild yeasts and mold and Bacillus spores without the addition of preservatives. The inclusion of 15% of the four-strain starter sourdough in the bread-making process led to enhanced safety and longer shelf life of the baked bread.

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 performed in order to study the possibilities for their aplication to obtain fermentable non-alcoholic and low-alcoholic beverages based on wort. Three yeast strains (two of Saccharomyces cerevisiae and one Saccharomyces diastaticus), were selected based on their good growth in the used medium and the pleasant organoleptic profile formed as a result of the fermentation carried out. The accumulated alcohol values varied between 0.05 and 0.22 % (w/w).

Bulgaria became the leading producer of lavender oil in the last years. Due to the lower quantity of essential oil large amounts of waste were generated which distilleries usually discard, although the residues are rich source of biologically active substances. The objective of this study was to obtain polyphenol-rich extracts from lavender waste and to investigate their chemical composition and antioxidant capacity. Two wastes (Mirkovo, Bulgaria, 2016) were investigated – steam distilled (SD-L) and CO2-extracted lavender (CO2-L). The major aroma constituents found were linalool and linalyl acetate – 30.68% and 25.82%, respectively, and the highest concentrations were found in the SD-L. The total flavonoids in CO2-L and SD-L were 2.91±0.11 and 3.72±0.20 mg/g dry matter residue, respectively. The higher amount of phenolic acids was observed in the SD-L waste – 2.62±0.19 mg/g, compared to 1.39±0.14 mg/g dry matter residue for CO2 extracted lavender. The antioxidant activity of the extracts was investigated by DPPH (SD-L – 355.48±23.12 µmol TE/g DW waste; CO2-L – 283.21±17.04 µmol TE/g DW waste) and FRAP (SD-L – 427.36±26.54 µmol TE/g DW waste; CO2-L – 311.29±18.17 µmol TE/g DW waste). Both methods suggested that SD-L residue had higher antioxidant capacity and polyphenol content.The lavender wastes (SD-L and CO2-L) showed strong antioxidant capacity with potential beneficial effect on addition in foodstuffs. For the first time lavender residues from CO2-extraction was investigated for its antioxidant activity, polyphenol composition and aroma metabolites, and comparison with SD-L was performed. In general, the results suggested that the lavender waste were promising source of antioxidants.