The aim of this study was to evaluate microbiological changes of traditionally produced horse meat sausages depending on maturing phases and season, to determine lactic acid bacteria and to research their inhibitory potential towards L. monocytogenes. Production season influenced significantly on total viable count, lactic acid bacteria, coagulase-negative cocci, enterococci and yeasts in final product (p<0.05). Lactic acid bacteria represented the most numerous microbial population, and significant number of yeasts and coagulase-negative cocci was also determined. Lactobacillus plantarum was determined as a dominant species in lactic acid bacteria population (56 %), while Weisella confusa (26 %), Lactobacillus fermentum (6 %), Lactobacillus pentosus (6 %), Lactococcus lactis subsp. lactis (2 %), Lactobacillus delbrueckii subsp. delbrueckii (2 %) and Weisella viridescens (2 %) were also isolated. Lactobacillus strains showed in laboratory conditions the strongest inhibitory effect towards L. monocytogenes. The results of this research may contribute to better understanding of specific issues of horse meat fermented sausages production compared to sausages produced from other sorts of meat and they can be used for sausage production standardization.

Coumarin-based compounds containing a chalcone moiety exhibit antimicrobial activity. These substances are potential drugs and it is important to determine their pKa values. However, they are almost insoluble in water. The dissociation constant was experimentally determined by potentiometric titration for 3-[3-(2-nitrophenyl)prop-2-enoyl]-2H-1-benzopyran-2-one because this compound shows good activity and solubility. A number of different computer programs for the calculation of the dissociation constant of chemical compounds have been developed. The pKa value of the target compound was calculated using three different computer programs, i.e., the ACD/pKa, CSpKaPredictor and ADME/ToxWEB programs, which are based on different theoretical approaches. The analysis demonstrated good agreement between the experimentally observed pKa value of 3-[3-(2-nitrophenyl)prop-2-enoyl]-2H-1-benzopyran- 2-one and the value calculated using the computer program CSpKa.