Modelling of factors influencing the effect of osmotic solution on reduction of selected microorganisms.

AIMS: The goal of this research is to model the effects of two osmotic solutions factors on the reduction of selected microorganisms, and to assess the application in osmotic dehydration process of animal raw materials from the aspect of microbiological safety. METHODS AND RESULTS: Sugar beet molasses and aquatic osmotic solution were prepared and inoculated with Escherichia coli, Listeria monocytogenes and Salmonella spp. Varied factors of osmotic solutions were: time, temperature and concentration of osmotic solutions. Samples of osmotic solutions were subjected to standard and modified microbiological ISO methods. The result showed that increase in factors had a positive effect on the reduction of microbiological load, while the time of the process was the most influential technological parameter. Number of L. monocytogenes was reduced to <10 CFU per g at the end of the process in the highest concentration of sugar beet molasses at all process temperatures. CONCLUSIONS: Developed mathematical models of reduction ratios for tested microorganisms were statistically significant, allowing good prediction of reduction ratio values based on applied factors. SIGNIFICANCE AND IMPACT OF THE STUDY: Obtained levels of reduction of all tested microorganisms present good base for the production of safe osmotically dehydrated products of animal origin.

Study of the chemical composition, proteolysis, volatile compounds, and textural properties of industrial and traditional Beaten (Bieno sirenje) ewe milk cheese.

The objective of this study was to determine the gross composition, proteolysis, and volatile and texture profiles during ripening of industrial (IND) and traditional (TRD) Beaten (Bieno sirenje) cheeses made by using ewe milk. In the course of the analyses, statistical differences were determined in some physicochemical parameters, nitrogen fractions, and total free amino acid levels between TRD and IND types of cheese. Higher levels of proteolysis were observed in IND cheeses than in TRD cheeses during ripening. Levels of residual ß- and αs-caseins were 72.2 and 48.7%, respectively, in 180-d-old TRD cheeses. However, the residual levels were 52.8% for ß-casein and 18% for αs-casein in IND cheeses. Similar differences were noted for the reversed-phase HPLC peptide profiles of 2 types of cheeses. Also, higher concentrations of peptides were eluted in IND cheeses than in TRD cheeses during ripening. A total of 73 volatile compounds, including alcohols (16), esters (17), acids (14), terpenes (7), ketones (5), aldehydes (4), and miscellaneous (10) were identified. The IND cheeses contained higher levels of carboxylic acids, esters, alcohols, and terpenes than the TRD cheeses; however, the same levels of methyl ketones were determined in the 2 types of cheeses at the end of ripening. These may be due to some differences (e.g., pasteurization and scalding temperature, among other factors) in the manufacture of the 2 types of Beaten cheeses. The textural profile of Beaten cheeses showed that TRD production method resulted in firmer, less fracturable, and stiffer cheeses than the IND production method. In conclusion, the results suggest that the use of industrial production method (pasteurization of cheese milk and curd scalding at 70°C) in the manufacture of Beaten ewe milk cheese enriched the volatile profile of the cheese.