An instrumental analysis of changes in the physicochemical and mechanical properties of smoked and mould salamis during storage

Abstract

The aim of the study was to determine changes in selected physicochemical characteristics during 60-day storage of Milano smoked salami (SS) and Milano mould salami (MS). The study included basic analyses as well as the analyses of texture, rheological properties, Fourier-transform infrared spectroscopy (FTIR), and low-field nuclear magnetic resonance (LF-NMR). Additionally, the influence of the place of sampling (from under the casing and from the centre of the salami bar) on the analyses was assessed. The analyses showed that the type of salami and storage time reduced the water content, Aw, and increased pH. The hardness of the SS was greater than that of the MS. In the initial period of storage there were differences in the values of rheological parameters in both types of salami, but they became equal over time. The FTIR analysis of the samples revealed characteristic amide I and amide II bands, as well as bands typical of fats and nucleic acids. The lack of visible shifts in the fatty bands suggests limited oxidation of unsaturated fatty acids during storage. The LF NMR analysis showed that the relaxation parameters depended on the type of salami and the place of sampling. The water bound in the salamis did not change its molecular dynamics during the storage of the products. Changes in the molecular rotational movements of protons showed that after 60 days of storage these movements were more limited in the smoked salami. Our study showed that the smoking process, the addition of mould, and the packaging method influenced the dynamics of water migration inside the product and its physicochemical characteristics.