Józef Korczak

Antioxidant properties of lupin seed products

Antioxidant properties of lupin flours and hulls were examined. Chemical composition (protein, fat, fatty acids, tocopherols and tannin contents) was determined and radiation effects were estimated (1, 5 and 10 kGy). Antioxidant properties of the ethanol lupin extracts were examined using the Rancimat and Oxidograph tests. Alpha-, gamma- and delta-tocopherols were found in the lupin oil. Lupin tannins contents in the flours were a few times higher than in the hulls. Antioxidant activity was found both in the flours and in the hulls. Correlation between the antioxidant properties and the tocopherol and tannin contents (the natural lupin antioxidants) was not found. Increasing doses of irradiation lowered antioxidant effects of lupin extracts; however, the antioxidant activities of some samples were higher. The observed negative changes in the tocopherols contents were effects of the irradiation dose as well as storage time.

Stabilisation of phytosterols by natural and synthetic antioxidants in high temperature conditions

The aim of the study was to assess the potential applicability of natural antioxidants in the stabilisation of phytosterols. A mixture of β-sitosterol and campesterol was incorporated into triacylglycerols (TAGs). The following antioxidants were added to the prepared matrix: green tea extract, rosemary extract, a mix of tocopherols from rapeseed oil, a mix of synthetic tocopherols, phenolic compounds extracted from rapeseed meal, sinapic acid and butylated hydroxytoluene (BHT). Samples were heated at a temperature of 180 °C for 4 h. After the completion of heating, the losses of phytosterols were analysed, as well as the contents of β-sitosterol and campesterol oxidation products. The total content of phytosterol oxidation products in samples ranged from 96.69 to 268.35 μg/g of oil. The effectiveness of antioxidants decreased in the following order: phenolic compounds from rapeseed meal>rosemary extract>mix of tocopherols from rapeseed oil>mix of synthetic tocopherols>green tea extract>sinapic acid>BHT.

Anti-polymerization activity of tea and fruits extracts during rapeseed oil heating

The aim of the study was to analyze the influence of natural antioxidants on polymerization of partially hydrogenated rapeseed oil heated in 170°C for 40h. In the research ethanolic extracts of green tea leaves (China Lung Ching), yellow tea leaves (China Kakecha), cranberry, blackberry, and lime were used. The yellow and green tea extracts were characterized by the highest content of total polyphenol and antioxidant activity. Polymers of triacylglycerols were found only in the polar fraction of heated oil. During heating, the increase of dimers, trimers, and oligomers was observed. However, it was dependent on the used additives and not directly related to the content of phenolic compounds and their antioxidant activity. The final content of polymers in oil samples increased in the fallowing order: green tea

Evaluation of Safety and Antioxidant Activity of Yellow Tea (Camellia sinensis) Extract for Application in Food

The article presents an evaluation of the safety of yellow tea (Camellia sinensis) extract consumption and its antioxidant activity in an animal model. Wistar rats were exposed through diet to 2, 6, and 10 g yellow tea extract/kg feed for 90 days. No signs of toxicity and no differences in mean body weight gain in the treated and control rats were recorded throughout the experiment. No statistically significant differences in hematology findings and clinical chemistry parameters were observed between controls and treated groups. Microscopic examination of tissue sections revealed no pathology attributable to yellow tea extract intake. Lipid peroxidation level in the liver was slightly increased in medium-dose males and high-dose females and decreased in two female groups receiving 2 and 6 g/kg of the extract tested. Content of carbonyl groups in protein, as well as the basal level of DNA damage, was not changed. In a majority of rats, the activity of antioxidant enzymes was increased except superoxide dismutase in high-dose groups, glutathione peroxidase in high-dose females, glutathione reductase in low- and mid-dose groups, and glutathione S-transferase in mid-dose females and high-dose males. It could be concluded that rats tolerated well dietary treatment with yellow tea extract up to 0.8 g/kg b.w./day for 90 days. Results showed that yellow tea extract at the doses tested did not demonstrate adverse effects and improved the antioxidant status in the liver of rats.

ANTIRADICAL CAPACITY AND POLYPHENOL COMPOSITION OF ASPARAGUS SPEARS VARIETIES CULTIVATED UNDER DIFFERENT SUNLIGHT CONDITIONS

BACKGROUND Asparagus officinalis has a high nutritional value. Asparagus is rich in a number of bioactive compounds, mainly flavonoids (quercetin), glutathione, vitamin C, vitamin E, fructans (inulin and fructooligosaccharides) and phytosterols (b-sitosterol). These compounds may play an important role in human health. The purpose of this study was to examine the antioxidant potential and polyphenol composition of white, pale-colored and green asparagus spears of different cultivars. METHODS Investigations were conducted on different asparagus spear extracts. The study included three colors of asparagus (white, pale-colored and green) from five different cultivars subjected to the ethanol extraction procedure. Total phenolic content was also determined by the Folin-Ciocalteu method. Polyphenol (phenolic acids and flavonols) composition was estimated using the HPLC method. The antioxidant properties of extracts were examined using DPPH, ABTS and metal ion chelating assays. RESULTS The highest contents of phenolic and flavonoids were observed in green asparagus from Grolim and the lowest in pale-colored asparagus from Gyjmlin. It was found that both the color of asparagus and the cultivar had a significant effect on the composition of phenolic acid and flavonols. Radical scavenging activity toward DPPH• and ABTS was highest for green asparagus cv. Grolim and Eposs. The greatest number of Fe ions was chelated by samples of green asparagus cv. Grolim and Huchels Alpha and pale-colored asparagus cv. Huchels Alpha. CONCLUSIONS It was shown that the antioxidant activity of asparagus spears measured by antiradical and chelating activity test depends on variety and color. The highest activity was found in green asparagus and the lowest was identified in white asparagus extracts. It has also been clarified that changes in flavonol and phenolic acid composition and increases in their diversity depends on growing with sunlight and variety. Asparagus can provide a valuable source of phenolic compounds in the human diet.