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The aim of the study was to determine the effect of oil degradation on the content of glycidyl esters (GEs) in oils used for the frying of French fries. As frying media, refined oils such as rapeseed, palm, palm olein and blend were used. French fries were fried for 40 h in oils heated to 180 °C in 30-min cycles. After every 8 h of frying, fresh oil and samples were analyzed for acid and anisidine values, color, refractive index, fatty acid composition, and content and composition of the polar fraction. GEs were determined by LC–MS. Hydrolysis and polymerization occurred most intensively in palm olein, while oxidation was reported for rapeseed oil. The degradation of oil caused increased changes in the RI of frying oils. Losses of mono- and polyunsaturated fatty acids were observed in all samples, with the largest share in blend. The highest content of GE found in fresh oil was in palm olein (25 mg kg−1) and the lowest content of GE was found in rapeseed oil (0.8 mg kg−1). The palm oil, palm olein and blend were dominated by GEs of palmitic and oleic acids, while rapeseed oil was dominated by GE of oleic acid. With increasing frying time, the content of GEs decreased with losses from 47 % in rapeseed oil to 78 % in palm oil after finishing frying.

The objective of this study was to investigate free amino acids composition of Polish honeys with different botanical origin. Honeys (n=18) with dominant buckwheat, raspberry, acacia, heather and goldenrod pollen, and honeydew honey were analysed. For determination of free amino acids liquid chromatography methods were applied. Identifi cation of 25 free amino acids was performed. Considerable variation in the total content of free amino acids ranging from 186.19 mg/kg to 921.08 mg/kg was stated. The dominant free amino acid in all types of honey was proline with the highest detected amount in one sample of heather honey 387.88 mg/kg. As an indicator of honeys with predominant raspberry and buckwheat pollen high concentrations of aspartic acid and asparagine (accounting for ca. 20 and more mg/kg) are suggested. The content of tyrosine, leucine, isoleucine and valine ranging from 10 to ca. 20 mg/kg was characteristic of raspberry and at concentrations above 20 mg/kg of buckwheat honeys. The cluster analysis showed the closest correlation between heather and goldenrod honeys. The largest distance was stated between buckwheat and all other honey groups. The results show that it was impossible to clearly distinguish the botanical origins of Polish honey samples based on their amino acid composition.