The scope of the experiments included analysis of the antimicrobial activity of ethanolic, methanolic and aqueous extracts against bacterial and fungal cultures and determination of the minimum inhibitory concentration of plant extracts tested microbial growth. Analysis of the antifungal and antibacterial activity was carried out by the disc diffusion method using paper discs. In the experiment 11 species of microorganisms – 8 bacterial and 3 fungal strains were used. The highest antimicrobial activity against the tested strains was demonstrated by black elder ( Sambucus nigra L.), black locust ( Robinia pseudoacacia L.) and lingonberry ( Vaccinium vitis-idaea L.) extracts. The study showed the diverse morphological activity of specific parts of elderberry and quince, which is the effect of different polyphenolic profile of these plants. The yeast Saccharomyces cerevisiae , Escherichia coli , Pseudomonas putida and Bacillus subtilis showed the highest sensitivity to the effect of extracts of the analysed plants. As a positive control three antibiotics – amphotericin B, vancomycin and amoxicillin with clavulanic acid were used.

Beer has been enjoyed by consumers for years. Today, hops are inextricably associated with this beverage. Although they have been the subject of research for decades, knowledge of their bittering components and interactions during the beer production process is still incomplete. Current literature clearly indicates that the bitterness experienced in beer comes from a much wider range of compounds than just iso-α-acids. Although compounds that can be classified into β-acids, humulinones, hulupones, hard resins, and polyphenols are characterized by lower levels of bitterness and are present in hops in lower quantities than α-acids, they might determine, together with them, the final level of bitterness in beer. Unlike α-acids, the influence of compounds from these groups, their transformations, changes in their content during the beer production process and factors that affect their final concentration in beer have not yet been thoroughly studied. In case of α-acids, it is known that factors, such as chemical composition of wort, its extract and pH, amount of hops added and α-acids’ content, boiling time, and temperature at which hops were added influence the level of bitterness. This phenomenon is further complicated when dry hopping is used. Due to the presence of humulinones, polyphenols, and α-acids, a relatively simple spectrophotometric determination of IBU can give erroneous results. IBU determination, especially in dry-hopped beers, should be coupled with HPLC analysis, taking into account appropriate bitterness coefficients.

Dry-hopping is the addition of hops to the wort on the cold side of the brewing process. Unlike standard hop additions, its main purpose is not to produce a characteristic bitterness but to extract as much of the hop essential oils as possible, which are largely lost in the standard hopping process. When dry-hopped, it is possible to obtain a beer with an aroma that is difficult to achieve when hops are used on the hot side of the brewing process. As a result, this process has become very popular in recent years, particularly in beers that belong to the ‘craft beer revolution’ trend. In addition, the usefulness of this process is increasing with the development of new hop varieties with unique aromas. This article presents the main components of hops, focusing on those extracted during the process. Changes in the composition of beer bittering compounds and essential oils resulting from this process are discussed. This paper presents the current state of the knowledge on the factors affecting the degree of extraction, such as hop dosage, the time, and temperature of the process. Issues such as process-related physicochemical changes, hop creep, low flavor stability, haze formation, and green flavor are also discussed.

The aim of the study was to characterise, quantitatively and qualitatively, the yeast microbiota found during spontaneous fermentation of grape musts obtained from the red grape varieties 'Rondo' and 'Regent'. For the research, grapes originating from two vineyards (Srebrna Góra and Spotkaniówka) located in southern Poland were used. Musts of the studied grape varieties provided a favourable environment for the growth of microorganisms. Musts obtained from fruits from the Spotkaniówka vineyard were characterised by a higher overall number of yeasts. A maximum number of cells were recorded from the fourth to the ninth day of the process, in all of the analysed musts. The growing season of 2013 proved to be the least favourable for the growth of microorganisms on grapes, which resulted in their smaller number in the batches during spontaneous fermentation. During the process, succession of different groups of yeasts was observed. It was initiated by Hanseniaspora uvarum and Candida railenensis strains, which, with the progress of spontaneous fermentation, were replaced by Saccharomyces cerevisiae strains. Metschnikowia pulcherrima and Pichia membranifaciens yeasts were identified at both the beginning and the end of the process. During fermentation, Zygoascus meyerae, Kluyveromyces lactis and Nakazawaea ishiwadae strains were also identified.

In recent years, demand for low-alcohol and alcohol-free beers has been rising. Of the many methods of producing such beers, many have expensive implementation requirements or drawbacks in terms of beer quality. The exploration of non-Saccharomyces yeast species presents a promising opportunity to overcome these challenges. These yeasts, with their diverse metabolic capabilities and unique flavor profiles, offer the potential to create innovative and flavorful low-alcohol beers. The study investigates the feasibility of using selected non-Saccharomyces yeasts for brewing low-alcohol beers, focusing on fermentation kinetics, physicochemical parameters, and the sensory attributes of the final product. The evaluated yeast species were Kluyveromyces lactis MG971263, Metschnikowia pulcherrima MG971247 and MG971250, Torulaspora delbrueckii MG971248, Wickerhamomyces anomalus MG971261, and W. onychis MG971246. Two strains of Saccharomyces cerevisiae were used as a control. The results of the study show that selected non-Saccharomyces yeast species might be used to produce low-alcohol beers. The non-Saccharomyces yeast allowed the researchers to obtain beers with an alcohol content in the range of 0.5–1.05%, while the control beer brewed with US-05 had an alcohol content of 3.77%. Among the evaluated strains, the strains M. pulcherrima MG971250 and T. delbrueckii MG971248 were found to be rated better in a sensory evaluation than the brewed and low-alcohol strains of S. cerevisiae.

The aim of the study was the physicochemical characterization of wines produced using indigenous yeasts isolated from spontaneously fermented grape musts, obtained from cold climate grapes.Saccharomyces cerevisiaeMH020215 andNakawazaea ishiwadaeMG971259 yeast strains were used in this study. The musts obtained from white and red grapes of Johanniter and regent varieties were used as a fermentation raw material. In the produced wines, content of ethyl alcohol, total extract, sugars, free amino nitrogen was analyzed, along with determination of total and volatile acidity and volatile compounds profile. Additionally, organoleptic evaluation was performed. Wines obtained with nativeS. cerevisiaeMH020215 strains were characterized with more favorable enological properties. Synthesis of desirable volatile compounds, especially esters, contributed to the creation of desirable aromatic profile of those wines. Moreover, those beverages contained higher levels of carbonyl compounds (especially acetaldehyde) and lower methanol content. Wines obtained usingN. ishiwadaeMG971259 cultures were represented by high total acidity level and substantial fusel alcohol content (mainly butanol, propanol), which resulted in an unfavorable sensory profile of the product.