[High pressure processing of spices in atmosphere of helium for decrease of microbiological contamination]. / Zastosowanie wysokiego cisnienia w atmosferze helu do obnizenia zanieczyszczenia mikrobiologicznego przypraw ziolowych.

The aim of the study was to investigate the microbiological decontamination of coriander and caraway when HPP technology was applied in elevated temperature in helium atmosphere. The HPP and heat treatment was conducted for 30 minutes at 800 and 1 000 MPa and temperature range was 60 - 121 degrees C. Contamination with aerobic mesophilic bacteria was decreased by about 2 logarithmic cycles. Total elimination of coliform and yeast and moulds was observed. The efficacy of HPP treatment under helium atmosphere depended on the content of the water in tested samples. It can be concluded that high pressure treatment under atmosphere of helium, combination of proper high pressure and time improved the microbiological quality of spices.

Ice VI freezing of meat: supercooling and ultrastructural studies.

While "classical" freezing (to ice I) is disruptive to the microstructure of meat, freezing to ice VI has been found to preserve it. Ice VI freeze-substitution microscopy showed no traces of structural alteration on muscle fibres compared with the extensive damage caused by ice I freezing. The different signs of the freezing volume changes associated with these two ice phases is the most likely explanation for the above effects. Ice VI exists only at high pressure (632.4-2216 MPa) but can be formed and kept at room temperature. It was found that its nucleation requires a higher degree of supercooling than ice I freezing does, both for pure water and meat. Monitoring of the freezing process (by temperature and/or pressure measurements) is, thus, essential. The possible applications of ice VI freezing for food and other biological materials and the nucleation behaviour of this ice phase are discussed.