The influence of solvent, storage time and temperature on the stability of the mycotoxin sterigmatocystin (STC) was investigated. STC calibrants (1.0 μg mlE-1) in acetonitrile, methanol and mixture of acetonitrile and methanol (50:50, volume/volume) were stored in dark glass bottles at (– 25), 4 and 25 °C for up to 8 weeks. Samples were analysed by high performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Obtained results indicate that more suitable solvents for storage of STC standard solutions at (–25 °C) are acetonitrile and mixture of acetonitrile and methanol (50:50, v/v), but not longer than for one week; for storage at 4 °C more suitable is mix of acetonitrile and methanol, but not longer than for one week.

There are different methods of egg yolk oil extraction, but still solvent extraction is commonly used. Due to the high cost of egg yolk powder production, extraction of lipids from liquid egg yolk remains very topical. Crude egg yolk oil obtained by solvent extraction from liquid egg yolk contains high amount of water which can decrease shelf life of egg oil promoting lipid oxidation. High concentration of residual solvents limits the usage of egg oil in food or in cosmetics due to the health risks. The aim of this study is to purify egg yolk oil obtained by solvent extraction from liquid egg yolk. Results show that it is possible to decrease the water content in egg oil from 14.26 ± 1.29% to 0.88 ± 0.13% by eliminating lecithin from egg oil. Solvent evaporation in the rotary film evaporator under the vacuum cannot remove solvents completely from the extract, but nitrogen streaming through the extract as a last step in evaporation process removes solvent residues, leaving behind high quality egg yolk oil suitable for food application.

Horseradish (Armoracia rusticana L.) is a perennial herb belonging to the Brassicaceae family and contains biologically active substances. The aim of the current research was to determine the most suitable extraction method and solvent for obtaining horseradish leaf extracts with high antiradical activity. For experiments fresh leaves of horseradish were extracted with seven different solvents: n-hexane, diethyl ether, 2-propanol, acetone, ethanol (95%), ethanolwater/acetic acid (80/20/1 v/v/v) and ethanol / water (80/20 by volume) using two extraction methods (conventional and Soxhlet). For all extracts, total phenolic, flavonoid content and DPPH˙, ABTS radical scavenging activity, and reducing power were determined using a spectrophotometric method. As the best solvent can be used ethanol. Total phenolic content and total flavonoid content was higher in Soxhlet extracts. Comparing to other plants, the proportion of flavonoids in the amount of total phenolics is average, and it increases by increasing the polarity of used solvent. It can be concluded that by using Soxhlet extraction method it is possible to obtain extracts that are effective antioxidants. A very strong and a strong correlation has been identified between levels of phenolic compounds and antioxidant capacities of the extracts.