Mirza Hadžiosmanović

Quantifying nonthermal inactivation of Listeria monocytogenes in European fermented sausages using bacteriocinogenic lactic acid bacteria or their bacteriocins: a case study for risk assessment.

Listeria monocytogenes NCTC10527 was examined with respect to its nonthermal inactivation kinetics in fermented sausages from four European countries: Serbia-Montenegro, Hungary, Croatia, and Bosnia-Herzegovina. The goal was to quantify the effect of fermentation and ripening conditions on L. monocytogenes with the simultaneous presence or absence of bacteriocin-producing lactic acid bacteria (i.e., Lactobacillus sakei). Different models were used to fit the experimental data and to calculate the kinetic parameters. The best model was chosen based on statistical comparisons. The Baranyi model was selected because it fitted the data better in most (73%) of the cases. The results from the challenge experiments and the subsequent statistical analysis indicated that relative to the control condition the addition of L. sakei strains reduced the time required for a 4-log reduction of L. monocytogenes (t(4D)). In contrast, the addition of the bacteriocins mesenterocin Y and sakacin P decreased the t(4D) values for only the Serbian product. A case study for risk assessment also was conducted. The data of initial population and t(4D) collected from all countries were described by a single distribution function. Storage temperature, packaging method, pH, and water activity of the final products were used to calculate the inactivation of L. monocytogenes that might occur during storage of the final product (U.S. Department of Agriculture Pathogen Modeling Program version 7.0). Simulation results indicated that the addition of L. sakei strains significantly decreased the simulated L. monocytogenes concentration of ready-to-eat fermented sausages at the time of consumption.

Microbial and physicochemical succession in fermented sausages produced with bacteriocinogenic culture of Lactobacillus sakei and semi-purified bacteriocin mesenterocin Y

The influence of the bacteriocinogenic culture Lactobacillus sakei (10(5)/g) and semi-purified bacteriocin mesenterocin Y (2560AU/kg) on the safety and quality of traditional Croatian fermented sausages was investigated. The addition of Lb. sakei and/or mesenterocin Y reduced microbial counts (P<0.05) in the final products. After 28 days of ripening, coagulase-negative cocci decreased 1.5-2.0log, yeasts 1.2-1.4log and enterococci 1.7-2.7log. In the case of the addition of Lb. sakei, the lactic acid bacteria count was significantly (P<0.05) higher at day 7 of ripening, and was accompanied by a lower pH and a higher amount of lactic acid (P<0.05). In the final product the amount of acetic acid was significantly lower. More intensive proteolysis and an increase in ammonia content were found at the beginning of fermentation, and in the second phase of ripening in the control samples, respectively. The free fatty acid concentration was significantly lower during the entire ripening process compared to the control (P<0.05). Semi-purified mesenterocin Y did not affect the sensory properties of the sausages, whilst the addition of Lb. sakei enhanced them.

The hygiene and quality of hare meat (Lepus europaeus Pallas) from Eastern Croatia

This research was conducted over two seasons (winter and spring) and comprised a total of 71 samples of hares shot in the eastern region of Croatia, and was aimed at examining the quality and hygiene of the meat. The degree of usefulness in relation to the total average weight of the shot hares was 66.54%. Chemical tests showed that the average amount of water in the meat of the hares amounted to 75.34%, protein 23.19%, fats 1.12% and ash 1.16%. Of the 71 samples examined, as many as 44 (61.97%) did not meet the requirements of the rules on microbiological food standards, of which in 19 samples (26.76%) this was due to the high level of aerobic mezophilic bacteria/g, 2 samples (2.82%) contained Staphylococcus aureus/g, and 37 samples (52.11%) were not satisfactory because they contained enterobacteria/g. In terms of heavy metals in kidney and meat samples, 17 (23.94%) did not meet the provisions of the rules on toxins, metals, metaloids and other harmful substances which may be found in food. Of these 15 kidney samples (88.24%) contained cadmium, and 2 samples (11.76%) mercury in amounts greater than the permitted concentration. Tests on liver samples from the hares (n=71) did not show organophosphorus pesticides, nor organochlorinated pesticides or polychlorinated biphenyls.

Influence of protective cultures on Listeria monocytogenes in fermented sausages : a review

Within the concept of protective technologies in the production of fermented sausages, in addition to known hurdles such as nitrites, NaCl, low water activity and low pH, of great importance is also the biopreservation procedure. This procedure involves the use of lactic acid bacteria, their metabolites and protective substances for the purpose of achieving antagonistic effect on the undesirable microflora. The importance of biopreservation is optimally manifested in the bacteriostatic and/or bactericidal action of protective cultures and bacteriocins on L. monocytogenes in various foods, including fermented sausages. Biopreservation is an additional factor in the production of safer food, but it alone can not warrant microbiological safety, and in order to have purport and effect, this method must be a superstructure to good manufacturing and good hygienic practice.

The chemical composition of the meat of fat dormice ( Glis glis L.)

The fat dormouse (Glis glis) is a traditional game species in the Republic of Croatia. Although today the fat dormouse is not frequently caught as game, it is still a source of animal protein in human nutrition in certain rural areas of Croatia. In this paper the chemical analysis of fat dormouse meat is presented. The average values for the quantity of water, fat, protein and ash in dormouse meat are comparable with the chemical composition of the meat of rabbits and brown hares, except for the important fact that rabbit and hare meat contains a greater quantity of fat on average. According to our results, the meat of fat dormice can be categorised as dietary food, characterised by a small percentage of fat (mean 2.83%) and a high amount of protein (mean 21.01%).

Influence of pre-slaughter resting time on shelf life and ammonia level of young bull meat during the storage.

The aim of present study was to evaluate the impact of pre-slaughter resting time of Simmental fattened bulls (n=40, age 14 to 24 months, m=250-350 kg) on shelf life and ammonia level of obtained meat. Animals were transported 140 km to local slaughterhouse, within two groups. First one included farm raised animals slaughtered immediately after arrival, while the second group consisted of extensively raised animals rested 36 hours prior to slaughter. The content of ammonia was measured at 1st, 3rd, 5th, 7th and 9th day of cold storage (2– 4 o ; C) in m. longissimus dorsi and m. gracilis. Initial ammonia level as well as ammonia levels measured during the storage in both muscles were higher in group of animals slaughtered immediately after arrival comparing to group of animals rested 36 hours prior to slaughter (P<0.001). At the end of storage period, meat became rotten in both groups leading us to conclude that 36 hours of resting prior to slaughter is not long enough to sufficiently suppress negative influence of stress on shelf life of meat.