P.R. Venskutonis

Effect of drying on the volatile constituents of thyme (Thymus vulgaris L.) and sage (Salvia officinalis L.)

Abstract The losses of volatile constituents in herbs and spices depend mainly on drying parameters and biological characteristics of the plants. In the present study, two methods were applied in the analysis of the effect of drying on the aroma constituents of the widely used herbs thyme ( Thymus vulgaris L.) and sage ( Salvia officinalis L.). The volatile constituents of herbs (fresh, freeze-dried and ovendried at 30 °C and 60 °C) were isolated by dynamic headspace and simultaneous distillation-extraction methods and analysed by capillary gas chromatography and coupled gas chromatography-mass spectrometry. In total, 68 compounds were identified in thyme and 44 in sage, and more than 100 components were screened quantitatively. A significant reduction in the amount of extracted volatiles was found only in the case of drying at 60 °C, mainly as a result of the loss of non-oxygenated monoterpenes. The character of the changes of the headspace volatiles was more complex, especially for thyme, the content of aroma compounds being the highest when the herb was dried at 60 °C. Some aroma assessment criteria (coefficient of efficiency C e ) are proposed on the basis of the results obtained.

Preliminary screening of antioxidant activity of some plant extracts in rapeseed oil

Abstract The antioxidant activity (AA) of acetone extracts of sage (Salvia officinalis L.), sweet grass (Hierocloe odorata Wahlnb.), sea buckthorn leaves (Hipophae rhamnoides L.), costmary (Balsamita major Desf., syn. Chrysanthemum balsamita L.), Roman camomile (Anthemis nobilis L.), and tansy (Tanacetum vulgare L.) were tested in refined, bleached and deodorised rapeseed oil at 40°C. The concentrations of the extracts added were in the range from 0.02 to 0.20% (w/w). The rate of oxidation was assessed by the measurement of peroxide value (PV) and calculation of such characteristics as induction period (IP), when PV reaches 20 meq kg−1, protection factor (PF), which is the ratio of IP of the sample with additive with IP of the sample without additive, and AA (the ratio of IP increase of the sample with extract with the IP increase of the sample with butylated hydroxytoluene). Sage and sweet grass extracts were found to be most effective in stabilising rapeseed oil, followed by tansy, Roman camomile, costmary and sea buckthorn in a decreasing order. The IP of rapeseed oil increased with extract concentration. AAs of the extracts added at different concentrations were the following: sage, sweet grass (0.05, 0.1 and 0.2%) and tansy (0.2%)xa0— very high, (PF>3); tansy and Roman camomile (0.1%)xa0— medium (PF=2–2.5), tansy (0.05%), Roman camomile (0.02 and 0.05%) and sea buckthorn (0.1 and 0.2%)xa0— low (PF=1.5–2.0), tansy (0.02%)xa0— very low (PF=1.0–1.5). The extracts of sea buckthorn (0.02 and 0.05%) slightly increased the formation of peroxides in rapeseed oil as compared with pure oil.

Evaluation of antioxidative properties of Geranium macrorrhizum and Potentilla fruticosa extracts in Dutch style fermented sausages

Antioxidative properties of Geranium macrorrhizum, Potentilla fruticosa and Rosmarinus officinalis (as a reference) extracts were evaluated in Dutch style fermented sausages. Extracts were incorporated into sausages during preparation. The sausages were subsequently fermented, tested and compared to a standard spices mix, traditionally used for the production of such sausages. Formation of the primary oxidation products - peroxides, and secondary - TBARS and hexanal was monitored. The polar extracts from Potentilla showed some antioxidant activity, especially in combination with ascorbate, however the activity was low compared to the standard spices mix. Polar extracts from Geranium showed only negligible antioxidant activity.

Antioxidant activity of sage extracts in rapeseed oil irradiated with UV‐rays

The antioxidant activities of sage acetone oleoresin and its methanol-water fractions were tested in rapeseed oil at 0.1% concentrations and 80 degrees C temperature after irradiation with UV-rays (exposition 0.5 h). It was determined that even little doses of UV irradiation induce oxidation process in rapeseed oil samples both with additives and without them. The antioxidant activity of a synthetic antioxidant BHT was much lower than that of the sage fractions at 80 degrees C and forced air oven conditions. This finding proves the advantage of sage extracts in comparison with BHT at high temperatures. It was also found that methanol-water fraction separated from acetone oleoresin had the highest antioxidant activity in terms of the formation of primary and secondary oxidation products. Oil sample with this additive had the highest protection factor (PF = 4.53) when the oil was not irradiated with UV rays. The data obtained showed that all sage extracts had very strong antioxidant activity (PF > 3).