engleski

Isotopic analysis of native cheese samples collected in the Republic of Croatia during 2021-2022

Seventy-seven cheese samples were collected from the entire territory of the Republic of Croatia. The samples were tested for the basic quality parameters of fat, protein, dry matter, salt, and pH. Their DELTA C (δ13C) and DELTA N (δ15N) values were determined and their mutual ratio was used to determine the geographical origin of the cheeses. Different types of cow’s, sheep’s, goat’s cheese, and their mixtures were tested over two years in order to determine whether the climatic conditions have had an influence on the ratio of isotopes, the quality of the cheese, and, ultimately, whether the isotope map is a good basis for examining the geographical origin of unknown cheese samples. Isotope-ratio mass spectrometric (IRMS) measurements were performed by IRMS Delta V Plus (Thermo Fisher Scientific, Bremen, Germany) coupled to Elemental Analyser FlashEA. Instruments were controlled by the Isodat 3.0 software (Thermo Fisher Scientific, Bremen, Germany). The isotopic ratios are reported in the delta notation as part per thousand (‰). Samples were analysed against in-house reference material calibrated by the certified reference materials VSLAP2 and VSMOW2 obtained from the International Atomic Agency, Vienna, Austria. All analyses were normalised against the following reference materials: IVA-CASEIN (δ13C=-26.980±0.05 ‰, δ15N=5.830±0.0 7‰) and Urea (δ13C=-36.540±0.18 ‰, δ15N=-2.350±0.09 ‰). Mean values were calculated from triplicate analyses and were (δ13C=-22.85±3.52 ‰, δ15N=4.80±1.01 ‰). Results showed that this method could be used for determination of quality and origin of cheeses in order to protect consumers and producers that follow good production practices.

geographical origin ; quality control ; isotopic ratios ; climatic conditions

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