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The aim of this study was to describe the dependence of hardness of processed cheeses on the proportion of disodium hydrogenphosphate (DSP), tetrasodium diphosphate (TSPP) and ⁄ or sodium salts of polyphosphate (POLY) in ternary mixtures of emulsifying salts. The samples were observed during a 30-day storage period (at 6°C). On the second day of storage, hardness of the samples with the individual DSP, TSPP or POLY were in the range of 1.65-1.83 N, 2.42-2.81 N and 5.98-6.53 N, respectively. Within zero or a very low proportion of POLY in the mixture, hardness of the processed cheeses increased rapidly (up to 14 N) at a specific ratio of DSP to TSPP in range of 1:1-3:4. Hardness of the samples containing the above-mentioned specific ratio was decreasing with the rising content of POLY (up to 60%) in the ternary mixtures. Within the prevailing content of POLY in the ternary mixtures (more than 60%), the phenomenon of a specific ratio of DSP to TSPP was no longer observed. With the increasing storage period (up to 30 days), hardness of the processed cheeses was slightly rising (in range of 2-4 N).

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Abstract. The contribution is focused on risk analysis in food microbiology. This paper evaluates the effect of selected factors on tyramine production in bacterial strains of Lactococcus genus which were assigned as tyramine producers. Tyramine is a biogenic amine sythesized from an amino acid called tyrosine. It can be found in certain foodstuffs (often in cheese), and can cause a pseudo-response in sensitive individuals. The above-mentioned bacteria are commonly used in the biotechnological process of cheese production as starter cultures. The levels of factors were chosen with respect to the conditions which can occur in this technological process. To describe and compare tyramine production in chosen microorganisms, generalized regression models were applied. Tyramine production was modelled by Gompertz curves according to the selected factors (the lactose concentration of 0-1% w/v, NaCl 0-2% w/v and aero/anaerobiosis) for 3 different types of bacterial cultivation. Moreover, estimates of model parameters were calculated and tested; multiple comparisons were discussed as well. The aim of this paper is to find a combination of factors leading to a similar tyramine production level.