Magdalena Rudzińska

Antioxidant properties of extracts from Ginkgo biloba leaves in meatballs

The aim was to determine the effect of Ginkgo leaf extracts on the stability of lipids and cholesterol in pork meatballs over 21days of refrigerated storage. The antioxidants used were characterized by their antioxidant activity towards lipids and cholesterol. Extracts were prepared from green and yellow leaves from Ginkgo biloba L. trees. Water, acetone and ethanol were used as extractants. The extracts showed stabilizing effects on both lipid and cholesterol oxidation processes. The lipid oxidation process of pork meatballs was mostly inhibited by the aqueous and ethanolic extracts of the yellow leaves. Their antioxidant activity was higher than that of BHT. All the extracts had a stabilizing effect on cholesterol and most of them inhibited the formation of oxidized derivatives. The acetone and ethanol extracts of green leaves and the ethanol extract of yellow leaves inhibited the formation of cholesterol oxidation products formation most effectively.

Degradation of phytosterols during storage of enriched margarines

Oxidative changes of phytosterols were recently studied in vegetable oils and some food products. Cholesterol-lowering properties of phytosterols and phytostanols are the main driver for formulating functional foods containing these compounds. Margarines enriched in plant stanols were stored at two typical temperatures for up to 18weeks. Analysed margarines contained four phytosterols: brassicasterol, campesterol, sitosterol, avenasterol and two phytostanols: sitostanol, campestanol. The content of phytosterols and phytostanols in margarines changed from 79mg/g in a control sample to 63mg/g and 55mg/g in samples stored for 18weeks at 4°C and 20°C, respectively. At the end of storage, contents of sitostanol decreased by 23% and 30%, while the amounts of oxidised sterols increased by 35% and 100%, respectively, for both temperatures. 7-Hydroxy derivatives dominated among all oxidised phytosterols and their content increased threefold at the end of storage. Epoxy derivatives exhibited a maximum after 6weeks of storage at 20°C and thereafter decreased constantly.

Fatty acids and sterols composition, and antioxidant activity of oils extracted from plant seeds.

This study determined and compared the contents of bioactive components in plant seed oils extracted with n-hexane (Soxhlet method) and chloroform/methanol (Folch method) from coriander, caraway, anise, nutmeg and white mustard seeds. Oleic acid dominated among unsaturated fatty acids in nutmeg and anise seed oils while petroselinic acid was present in coriander and caraway oils. Concerning sterols, β-sitosterol was the main component in seed oils extracted with both methods. The content of total phenolics in nutmeg, white mustard and coriander seed oils extracted with chloroform/methanol was higher than in their counterparts prepared with n-hexane. The seed oil samples extracted according to the Folch method exhibited a higher ability to scavenge DPPH radicals compared to the oil samples prepared with the Soxhlet method. DPPH values of the methanolic extracts derived from oils produced with the Folch method were also higher than in the oils extracted with n-hexane.

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.

Impact of Species and Variety on Concentrations of Minor Lipophilic Bioactive Compounds in Oils Recovered from Plum Kernels

The profile of bioactive compounds (carotenoids, tocopherols, tocotrienols, phytosterols, and squalene) in oils recovered from the kernels of 28 plum varieties of hexaploid species Prunus domestica L. and diploid plums Prunus cerasifera Ehrh. and their crossbreeds were studied. Oil yields in plum kernels of both P. cerasifera and P. domestica was in wide ranges of 22.6-53.1 and 24.2-46.9% (w/w) dw, respectively. The contents of total tocochromanols, carotenoids, phytosterols, and squalene was significantly affected by the variety and ranged between 70.7 and 208.7 mg/100 g of oil, between 0.41 and 3.07 mg/100 g of oil, between 297.2 and 1569.6 mg/100 g of oil, and between 25.7 and 80.4 mg/100 g of oil, respectively. Regardless of the cultivar, β-sitosterol and γ-tocopherol were the main minor lipophilic compounds in plum kernel oils and constituted between 208.5 and 1258.7 mg/100 g of oil and between 60.5 and 182.0 mg/100 g of oil, respectively. Between the studied plum species, significant differences were recorded for δ-tocopherol (p = 0.007), 24-methylenecycloartanol (p = 0.038), and citrostadienol (p = 0.003), but they were insufficient for discrimination by PCA.

Lipophilic bioactive compounds in the oils recovered from cereal by‐products

BACKGROUND The by-products of seven different cereal grains were investigated as a source of extractable oil, rich in lipophilic bioactive compounds. RESULTS Oil yields (g kg(-1) DW) recovered from cereal by-products were as follows: 189 (rice bran) > 112 (wheat germ) > 74 (corn bran) > 58 (oat bran) > 41 (buckwheat bran) > 39 (spelt bran) > 33 (wheat bran) > 27 (rye bran). The main fatty acids identified in the studied oil samples were palmitic acid (11.39-17.23%), oleic acid (11.76-42.73%), linoleic acid (35.54-62.65%) and α-linolenic acid (1.05-9.46%). The range of total tocochromanols and phytosterols in the obtained oils was 0.369-3.763 and 1.19-35.24 g kg(-1) of oil, respectively. The oils recovered from buckwheat and corn bran, and wheat germ were dominated by tocopherols (99.9, 84.2 and 96.5%, respectively), whereas the oat, rice, rye, spelt, wheat bran oils were rich in tocotrienols (73.9, 79.6, 78.1, 90.6 and 73.8%, respectively). The campesterol and β-sitosterol constituted 10.1-32.5 and 30.4-63.7%, respectively, of total phytosterols contents identified in all of the studied samples. CONCLUSION The present study demonstrated that oils recovered from the cereal by-products are richer sources of bioactive compounds, compared with traditional oils.

Effect of Flaxseed Meals and Extracts on Lipid Stability in a Stored Meat Product

Flaxseeds have been recently in focus due to the antioxidant capacity of some of their compounds. However, there is a lack of easily accessible information concerning their activity against lipid oxidation in food systems. Therefore, the aim of the study was to determine the effect of defatted meals (DFM) and the aqueous extracts (AFE) obtained from brown and golden flaxseeds on lipid oxidation in pork meatballs. Fatty acid composition, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and cholesterol content were monitored during 6 months of freezer storage. Cholesterol oxidation products were identified and quantified. Both DFM and AFE limited fatty acid and cholesterol oxidation during meatball storage. Their antioxidant effect depended on flax variety (brown or golden) and preparation type (DFM or AFE). Lower level of PV and TBARS, compared with the ones with AFE, were noted in meatballs with DFM. Both DFM and AFE, from the brown seed variety, protect the lipids against oxidation to a higher extent. During the storage, a cholesterol degradation was observed. AFE (particularly from the brown variety) limited changes in cholesterol content. Moreover, they stabilized fatty acid composition of stored meatballs. However, DFM efficiently inhibited cholesterol oxidation.

Model studies on the formation of volatile compounds generated by a thermal treatment of steryl esters with different fatty acid moieties

The consumption of plant sterols is reported to have a beneficial effects on human health, i.e. phytosterols are known for their cholesterol-lowering properties. Whereas, they are prone to oxidation and currently there is ongoing worldwide research aimed at the biological effect of phytosterol oxides. In this study volatile compounds formed during thermal degradation of stigmasteryl esters were identified. The research was conducted using standards of stigmasterol, fatty acids and stigmasteryl esters as well as fat enriched with stigmasteryl esters which were thermally treated at 60°C and 180°C for 12h. Volatile compounds were characterised by SPME-GC-MS. Among the volatiles formed during heating of stigmasteryl esters aldehydes, ketones, alcohols and hydrocarbons were found. The mechanism of the formation of volatile compounds from sterol esters was related to oxidation of steryl and fatty acid moieties. In particular, 2-methyl-3-pentanone and 5-ethyl-6-methyl-3-hepten-2-one were identified as unique degradation products formed from degradation of the steryl moiety specifically, and a mechanism of their formation was suggested. Both volatiles could be a good indicator of thermo-oxidative degradation of functional food products enriched in phytosterols and their esters.

Galactomyces geotrichum – moulds from dairy products with high biotechnological potential

The article reviews the properties of the Galactomyces geotrichum species, the mould that is most important for the dairy industry. G. geotrichum mould has been isolated from milk, cheeses and alcoholic beverage. Its presence in food products makes it possible to obtain a characteristic aroma and taste, which corresponds to the needs and preferences of consumers. G. geotrichum plays an important role in ecology, where the mould is employed for the degradation of various hazardous substances and wastewater treatment. It has also been found to have potential for biofuel production. In addition to this, G. geotrichum can be applicable in two further major areas: agriculture and health protection.

Physicochemical characteristics of the cold-pressed oil obtained from seeds of Fagus sylvatica L.

A physicochemical characteristic of the cold-pressed oil obtained from seeds of common beech (Fagus sylvatica L.) has been presented. This plant may be considered as unconventional oilseeds crops because of relatively high content of fat (27.25%). The analyzed beech seeds oil has been classified as oleic-linoleic acids oil with more than 76% percentage share of those species. Beech seeds oil contains 4.2% of gamma-linolenic acid (GLA). Unique characteristic is the high content of γ-tocopherol (75.4mg/100g) and δ-tocopherol (34.05mg/100g). γ-Tocopherol is effective scavengers of reactive nitrogen species and prevents DNA bases nitration, what makes beech seeds oil interesting raw material in the production of cosmetics. Additionally the content of carotenoids, very effective photooxidation inhibitors, is at high level in comparison with other cold-pressed oils. It was demonstrated that PCA analysis may help to determine the authenticity of oil obtained from beech seeds.