Investigation of Different Regimes of Beer Fermentation with Free and Immobilized Cells

Three different kinetic models – Monod’s model, Monod’s model with substrate inhibition, and Monod's model with substrate and product inhibition were developed for studying of beer fermentation with free and immobilized cells at different main fermentation and maturation temperatures. The most accurate model was Monod's model with substrate and product inhibition. It showed that maturation temperature had no effect on primary metabolism but it affected significantly the secondary metabolites production. In regard to carbonyl compounds and esters, the increase in maturation temperature led to different trends for free and immobilized cells. Regarding the higher alcohols, the increase in maturation temperature resulted in increase in their yield coefficients for both immobilized and free cells. A sensory evaluation of beers produced with free and immobilized cells were also carried out and the results showed similar results for two beer types

Investigation of Fermentation Regimes for the Production of Low-alcohol and Non-alcohol Beers

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

Tehnike minimalne obrade za proizvodnju i čuvanje hrane prilagođene individualnim potrebama

Tailor-made foods, also known as foods with programmable properties, are specialised systems with unique composition prepared by different methods, using the known mechanisms of action of their bioactive ingredients. The development of tailor-made foods involves the evaluation of individual components, including bioactive substances derived from waste products of other productions, such as essential oils. These components are evaluated both individually and in combination within food compositions to achieve specific functionalities. This review focuses on the application of minimal processing technologies for the production and preservation of tailor-made foods. It examines a range of approaches, including traditional and emerging technologies, as well as novel ingredients such as biomolecules from various sources and microorganisms. These approaches are combined according to the principles of hurdle technology to achieve effective synergistic effects that enhance food safety and extend the shelf life of tailor-made foods, while maintaining their functional properties. §Paper was presented at the 11th Central European Congress on Food and Nutrition CEFood2022, Čatež ob Savi, Slovenia, 27-30 September 2022Hrana prilagođena individualnim potrebama, poznata i kao hrana s prilagođenim svojstvima, je posebno pripremljena hrana jedinstvenog sastava, dobivena različitim metodama koje se zasnivaju na dobro poznatim mehanizmima djelovanja biološki aktivnih sastojaka. Razvoj takve hrane obuhvaća procjenu pojedinih sastojaka, uključujući biološki aktivnih spojeva izoliranih iz otpada nastalog u proizvodnji, poput eteričnih ulja. Ti su spojevi ispitani pojedinačno i u kombinaciji sa sastojcima hrane, u svrhu razvoja određenih funkcionalnih svojstava. U fokusu ovog revijalnog prikaza je primjena tehnika minimalne obrade za proizvodnju i čuvanje hrane prilagođene jedinstvenim potrebama. Razmotreni su različiti pristupi, uključujući tradicionalne i nove tehnologije, te novi sastojci, poput biomolekula što potječu iz različitih izvora i mikroorganizama. Ti su pristupi kombinirani na principu tehnologije preprekama, za uspješno postizanje sinergijskog učinka koji poboljšava sigurnost i produljuje vrijeme skladištenja hrane, dok istovremeno zadržava njezina funkcionalna svojstva

Shiga toxin targeted strategy for chemotherapy and cancer immunotherapy application using copper-free « Click » chemistry

Pas de résuméRecently targeted therapies appeared as attractive alternatives to classical antitumoral treatments. The approach, developed on the concept of targeting drug to cancer cells, aims to spear normal tissues and decrease the side effects. This doctoral dissertation focuses on developing new anticancer targeted treatments in the field of chemotherapy and cancer immunotherapy by exploiting an original targeting moiety, the B subunit of Shiga toxin (STxB). Its specific properties, such as, recognition with its receptor Gb3 overexpressed in cancer cells or in antigen-presenting cells, its unconventional intracellular trafficking, guided the choice of this protein as targeting carrier. This project is based in the use of copper-free Huisgen [3+2] cycloaddition as a coupling method, which led to successful preparation of various conjugates for their respective applications. The concept was first validated by STxB-biotin conjugate. The high yield of the reaction and the compatibility between the targeting carrier and the chemical ligation promoted the design of conjugates for chemotherapy and immunotherapy. Two therapeutical optimizations of previously developed strategy in STxB drug targeting delivery were investigated: synthesis of multivalent drug-conjugates and synthesis of conjugates containing a highly potent anticancer agent. Both approaches exploited three anticancer agents: SN38, Doxorubicin and Monomethyl auristatin F. The disulfide spacer, combined with various self-immolative systems, insured drug release. Two cytotoxic conjugates STxB–doxorubicin (STxB-Doxo) and STxB-monomethyl auristatin F (STxB-MMAF) were obtained in very high yield and demonstrated strong tumor inhibition activity in the nanomolar range on Gb3-positive cells. Based on the results the STxB-MMAF conjugate was investigated on a mouse model. The project aimed also to develop STxB bioconjugates for vaccine applications. Previous studies used B subunit as a targeting carrier coupled to an antigenic protein in order to induce a more potent immune response against cancer. The conjugates were prepared using a commercial linker, requiring modifying the antigen at first place, or by oxime ligation, where slightly acidic conditions promoted the coupling. Thus, the work presented herein proposed an alternative ligation via copper-free click chemistry especially for more sensitive antigenic proteins. Various types of conjugates were synthesised and investigated for their immune stimulation properties. The STxB targeting strategy was also applied to the development of a new vaccine based on coupling the targeting carrier to alpha-GalCer, one of the most potent immune stimulating agents known. The work focused on the synthesis of functionalised alpha-Galcer with an azide handle

COMPARATIVE EVALUATION OF LACTOBACILLUS PLANTARUM STRAINS THROUGH MICROBIAL GROWTH KINETICS

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

Modeling in Brewing—A Review

Beer production has over a thousand-year tradition, but its development in the present continues with the introduction of new technological and technical solutions. The methods for modeling and optimization in beer production through an applied analytical approach have been discussed in the present paper. For this purpose, the parameters that are essential for the main processes in beer production have been considered—development of malt blends, guaranteeing the main brewing characteristics; obtaining wort through the processes of mashing, lautering and boiling of wort; fermentation and maturation of beer. Data on the mathematical dependences used to describe the different stages of beer production (one-factor experiments, modeling of mixtures, experiment planning, description of the kinetics of microbial growth, etc.) and their limits have been presented, and specific research results of various authors teams working in this field have been cited. The independent variables as well as the objective functions for each stage have been defined. Some new trends in the field of beer production have been considered and possible approaches for their modeling and optimization have been highlighted. The paper suggests a generalized approach to describe the main methods of modeling and optimization, which does not depend on the beer type produced. The proposed approaches can be used to model and optimize the production of different beer types, and the conditions for their application should be consistent with the technological regimes used in each case. The approaches for modeling and optimization of the individual processes have been supported by mathematical dependencies most typical for these stages. Depending on the specific regimes and objectives of the study, these dependencies can be adapted and/or combined into more general mathematical models. Some new trends in the field of beer production have been considered and possible approaches for their modeling and optimization have been highlighted

EFFECT OF MINT ESSENTIAL OIL ADDITION ON LACTIC ACID FERMENTATION IN STIRRED TANK BIOREACTOR

The increasing consumer’s demand for healthy beverages lead to the production of lactic acid fermented wort-based beverages. They can be classified as functional because of wort vitamins, antioxidants and fibres content and probiotic properties of used lactic acid bacteria strain. However, lactic acid wort- based beverages are not well accepted by consumers because of their poor sensory characteristics. The aim of this study was to investigate the effect of the addition of 0.025 and 0.05 % (v/v) mint (Mentha piperita) essential oil on probiotic, antioxidant, and sensorial properties on lactic acid wort-based beverages. Lactic acid fermentation was carried out at 25°C in a stirred bioreactor without aeration. The addition of mint essential oil inhibited lactic acid fermentation but all the beverages produced can be classified as functional. Although the beverage with 0.05% mint essential oil showed the highest total phenolic compounds and antioxidant activity, measured by cupric reducing antioxidant power (CUPRAC), ferric reducing antioxidant power (FRAP) and ABTS radical scavenging assay, it received the lowest score by tasting panel because its strong taste and aroma. The results obtained will be used for modeling of lactic acids fermentation with addition of mint essential oil for the production of beverage with high biological value and acceptable sensory profile

STUDY OF THE FERMENTATION FOR THE PRODUCTION OF FUNCTIONAL WORT- BASED BEVERAGES WITH OR WITHOUT LEMON ESSENTIAL OIL

Wort can be used as a basis for functional soft drinks production due to its high content of fibres, vitamins and antioxidants. In the present work, the fermentation of wort produced with 60% Pilsen malt, 20% Vienna malt and 20% Caramel Munich ІІ malt with or without the addition of 0.05% (v/v) lemon essential oil was studied. Fermentations were carried out at a constant temperature of 10 °C with the probiotic yeast strain Saccharomyces cerevisiae var boulardii Y1. The dynamics of the extract, the alcohol content and the concentration of viable cells were monitored. Essential oil had negative impact on the extract consumption and ethanol production, but did not affect the biomass growth. The total phenolic content, phenolic acid and flavonoid phenolic compounds were determined because of their antioxidant activity. At the end of the fermentation the beverage with essential oil showed higher concentration of total phenolic content, phenolic acid and flavonoid phenolic compounds. The antioxidant activity was determined by the radical scavenging assay (DPPH) and ferric reducing antioxidant power (FRAP). The DPPH radical scavenging activities were almost equal for both functional beverages but the results from FRAP assay were higher for the beverage produced with lemon essential oil

Modelling of Malt Mixture for the Production of Wort with Increased Biological Value

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

Modelling of Malt Mixture for the Production of Wort with Increased Biological Value

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