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Magnesium participates in numerous enzymatic reactions in the human body and it has essential role in the maintenance of the antioxidant system. Since several magnesium compounds have been applied in the food and pharmaceutical industry, our purpose was to investigate the antioxidant/free radical scavenging activity of some magnesium compounds in vitro. The antioxidant/prooxidant effect of inorganic salts (e.g. MgCl2) and organic complexes (e.g. Mg-gluconate) was determined with chemiluminometric method (H2O2/•OH-microperoxidase-luminol) and heme mediated LDL oxidation (LDL-heme-H2O2 ) in vitro. It has been stated that the chemiluminescence method and LDL (low density lipoprotein) oxidation measurement is applicable in the presence of magnesium salts and complexes. Most of the compounds do not generate free radicals and the antioxidant/prooxidant effect depends on the quality of the ligand and the concentration. In the concentration range used, some representatives of the magnesium compounds (MgO, Mg-gluconate, Mg-polygalacturonate) investigated showed radical generating activity measured with chemiluminescence method, whereas the LDL oxidation has not been affected. Magnesium citrate and malate proved to be antioxidants measured with the chemiluminescence method and they slightly accelerate the LDL oxidation in the system and in the concentration applied. In vitro some of the ligands of magnesium compounds showed antioxidant activities.
Water content of dry sausages may decrease due to improper ripening and storage as well. As a consequence, an outer crust appears on the surface of the products. The aim of the industry is either to eliminate the presence of outer crust, or decrease its occurrence. The thickness of outer crust can be estimated by non-destructive ultrasound technique. As the propagation time and attenuation of ultrasonic waves vary in the materials with different water content, the thickness of outer crust and the normal texture, respectively, can be estimated on the basis of these characteristics. The propagation and attenuation values are typical for the given layers. Thus, by measuring total attenuation and total width of the product, the thickness of outer crust can be calculated by means of the velocity and attenuation coefficients of ultrasonic waves. Results of this non-destructive measurement may support the proper adjustment of ripening and storage parameters such as temperature and humidity.
The aim of the study was to select the most suitable freezing and thawing method for preserving the quality of pasta flata type Parenica cheese comparing different methods: slow, shock (circulated air) and cryogenic freezing and thawing at room temperature and in a refrigerator, respectively. To observe the effects of these methods on some cheese properties weight, pH, and dry-matter content were measured, stringiness was examined, and compression test were performed for texture analysis. Thermophysical properties were determined by DSC: unfreezable water content, onset point of melting, and latent heat. Sensory analyses were also carried out by profle analysis. Results of objective and subjective measurements showed similar trends: characteristics of cheese samples frozen in circulated air and thawed in refrigerator resembled the most to the control sample.
