Phenolic compounds were extracted from thyme (Thymus vulgaris L.), oregano (Origanum vulgare L.) and marjoram (Origanum majorana L.) with 95% ethanol. A number of antioxidant and radical-scavenging capacity tests were performed on the prepared extracts using colorimetric assays and model system studies. Specifically, these included determining the content of total phenolics, antioxidant efficacy in a linoleic acid-ferric thiocyanate model system, reducing power, scavenging effect on 2,2'-diphenyl-1-picrylhydrazyl radical, and hydroxyl radical-scavenging activity by electron paramagnetic resonance spectroscopy. Moreover, the efficacies of the prepared herb extracts were investigated in a real-life food product: the stabilization of butter against oxidation.
Amarowicz R., Żegarska Z., Pegg R. B., Karamać M., Kosińska A. (2007): Antioxidant and radical scavenging activities of a barley crude extract and its fraction. Czech J. Food Sci., 25: 73-80.Phenolic compounds were extracted from the Candle variety of hull-less waxy barley with 80% (v/v) methanol to yield a crude preparation. Seven fractions (I-VII) were separated from the barley extract so obtained on a Sephadex LH-20 column using methanol as the mobile phase. Nearly 80% of the phenolics extracted from barley were comprised in the first three fractions. The measurements of the antioxidant activity using a β-carotene-linoleate model system, radical scavenging capacity against DPPH•, and reducing power based on the reduction of a Fe 3+ /K 3 Fe(CN) 6 complex to the ferrous state were assessed in the barley crude extract and its fractions. The results indicated that barley possess marked antioxidant and antiradical capacities as compared to other grains such as wheat, rye, and triticale. Furthermore, the methanolic extract of the waxy barley sample and its fractions resembled in the aforementioned activities those from leguminous seeds, rapeseed and pulses. Phenolic constituents contained in barley may have a future role as ingredients in the development of functional foods.
Milk fat is characterised by a high variability in the fatty acid composition caused by multiple factors, among which belongs the lactation period. The research by JAWORSKI and JAWORSKA (1973) indicated that substantial differences in the quantitative fatty acid composition of milk fat linked to the lactation period occurred mainly in the early and late periods of lactation. According to the authors' results, milk fat of cows in the early period of lactation was characterised by higher concentrations of unsaturated fatty acids (especially in the second month) in comparison to the later lactation phases. In the third month of lactation, the concentration of higher saturated fatty acids increased, whereas that of unsaturated acids (mainly oleic and linoleic) decreased. The results of a study by PALMQUIST et al. (1993) indicated that the milk fat from cows in the first week of lactation had a low content of short-chain fatty acids (except for C4:0 acid) and a high content of C18:0 and C18:1 acids. The concentration of short-chain fatty acids in the milk fat increased until the 8 th week of lactation, which was accompanied by a decrease in the fatty acids from the C18 group.So far, the studies performed concerned the determination of the total fatty acid composition of milk fat of individual lactating cows. Little is known about the variation of trans fatty acid isomers among individual samples of milk in the lactation period. The objective of the present investigation was to evaluate the content of trans unsaturated fatty acids and the concentration of cis-9 trans-11 C18:2 acid (CLA) in the colostrum and milk fat from individual cows in the early period of lactation. The trans fatty acids as well as cis-9 trans-11 C18:2 (CLA) were determined in the colostrum and milk fat of individual cows during up to 82 days of lactation. The analyses were performed using gas chromatography (GLC) on a capillary column (CP Sil 88) combined with the method of argentation thin-layer chromatography (Ag-TLC). The results obtained in the study indicated that the milk fat of individual cows, kept under identical living and feeding conditions, was characterised by an extremely high variability of trans isomers concentration, especially of those of C18:1 acid. The differences referred not only to the total content of trans C18:1 isomers but also to the proportion of trans-10 and trans-11 isomers of C18:1. In some fat samples, a high concentration of trans C18:1 isomers was observed and trans-10 isomer of C18:1 was found to dominate. In the case of all the cows, the colostrum fat was characterised by a lower average content of the examined acids as compared to the milk fat. The average value of CLA in the colostrum fat of all the cows under study was 0.34%, and in the milk fat 0.42% of total fatty acids.
The Contents of Trans Fatty Acids and CLA in Cow Colostrum and Milk Fat in the Early Lactation Period
The content of trans C18:1, trans C18:2 and cis9trans11 C18:2 (CLA) in the marketed fat blends was evaluated by capillary gas chromatography and silver thin-layer chromatography. For comparison, the level of these acids was also determined in commercial butter, purchased at the same time. The content of trans C18:1 in fat blends showed that half of the examined products contained trans C18:1 at 1.9-4.4%, while the other half contained 8.2-24.2% trans fatty acids. The fat blends with a high total content of trans C18:1 were characterized by a high proportion of trans 6-8 and trans 9 isomers. The trans 9 C18:1 in these products constituted 15.0-22.5% of the total trans C18:1. The level of trans C18:2 in fat blends examined ranged from 0.3 to 1.1%. Seven of the 18 tested fat blends contained, apart from cis-trans and trans-cis C18:2, also trans-trans C18:2 in the 0.03-0.4% range. In all fat blends examined, CLA was present. The products with a low level of trans C18:1 contained CLA at 0.3-1.0%. The content of CLA in the fat blends with high level of trans C18:1 did not exceed 0.3%.
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