The aim of this paper was the analytical evaluation of human milk fat substitutes (HMFS) by the calorimetric and spectroscopic methods. The HMFS were obtained by enzymatic interesterification of blend of lard or milk fat with rapeseed oil and concentrate of fish oil. The enzymatic reactions were carried out at 60, 70, and 80°C for 2 h. A commercially immobilized 1,3-specific lipase, Lipozyme RM IM, was used as a biocatalyst. Oxidative stability of HMFS was determined using the calorimetric method. The oxidative induction time was obtained from the pressure differential scanning calorimetry curves. Peroxide value (PV) and anisidine value were determined using spectroscopic method. Interesterification caused a decrease in oxidative stability. Samples with lower induction times were characterized by higher PV. There was also a strong relation between total polar compound content and induction time. The induction times obtained for analyzed fats can be used as primary parameters for the assessment of the resistance of tested fats to their oxidative decomposition.

Two series of benzimidazole derivatives were sythesised. The first one was based on 5,6-dinitrobenzimidazole, the second one comprises 2-thioalkyl-and thioaryl-substituted modified benzimidazoles. Antibacterial and antiprotozoal activity of the newly obtained compounds was studied. Some thioalkyl derivatives showed remarkable activity against nosocomial strains of Stenotrophomonas malthophilia, and an activity comparable to that of metronidazole against Gram-positive and Gram-negative bacteria. Of the tested compounds, 5,6-dichloro-2-(4-nitrobenzylthio)-benzimidazole showed the most distinct antiprotozoal activity.Benzimidazole derivatives are of wide interest because of their diverse biological activity and clinical applications [1]. This ring system is present in numerous antiparasitic, fungicidal, anithelemintic and anti-inflammatory drugs [2][3][4][5]. Also, some benzimidazole nucleosides, particularly 5,6-dichlorobenzimi-dazole-1-b-D-ribofuranoside (DRB) and its 2-substituted derivatives show activity against human cytomegalovirus [6]. It is also known that 5,6-dinitrobenzimidazole can substitute 5,6-dimethylbenzimidazole in the vitamin B 12 molecule in Corynebacterium diphteriae [7] and 2-trifluorobenzimidazoles are Vol. 49 No.

The aim of this study was the analytical evaluations of human milk fat substitutes (HMFS) synthesized via enzymatic interesterification of lard and milk thistle oil mixtures by a immobilized commercial sn-1,3-specific lipase, using calorimetric and chromatographic methods. The mixtures of lard and milk thistle oil at mass ratio 6:4 and 8:2 were interesterified for 2, 4 and 6 h at the temperature of 60°C. The determination of fatty acid composition was carried out by gas chromatographic analysis of fatty acid methyl esters. The positional distribution of fatty acids in the sn-2 and sn-1,3 positions of triacylglycerols was based on the ability of the pancreatic lipase to selectively hydrolyze ester bonds in the sn-1,3 positions. Pressure differential scanning calorimetry (PDSC) method was used for the determination of the oxidative stability of HMFS. The oxidative induction time was obtained from the PDSC curves. Due to enzymatic interesterification of mixtures of lard and milk thistle oil, new HMFS that have a similar regiospecific structure of triacylglycerols to human milk fat can be produced. The induction time obtained from PDSC measurements can be used as a parameter for the assessment of the resistance of tested fats to their thermal-oxidative decomposition.

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The aim of this paper was to assess the oxidative stability of structured lipids synthesized by enzymatic interesterification of a blend of lard and rapeseed oil with concentrates of n -3 fatty acids. Differential scanning calorimetry was used to evaluate the oxidation induction time of interesterified fats as a parameter assessing resistance of tested fats to their thermal-oxidative decomposition. Moreover, the IR spectra registered in the classic spectral range (4000-400 cm -1 ) were used to differentiate the samples of interesterified fats. The results show that the interesterification process decreased the induction time. Increased content polar fraction in the interesterified fatty product can reduce its resistance to oxidation. FT-IR data of selected spectral ranges correlate with the value of induction time at a statistically significant level. This is a proof that chemical changes occurring during different treatments of the starting mixture can be monitored by FT-IR spectroscopy. Moreover, obtained correlations can be used for the evaluation of an induction value of an unknown oil sample.