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Supercritical fluid extraction of bioactive ingredients from rose hip and yarrow residues – valorisation of filter tea industry by-products

Aside from water, tea is the most popular beverage in the world, being produced globally on a mass scale. On Serbia and surrounding countries, the filter tea industry based its production on different aromatic and medicinal plants, as well as different fruits, such as berries and apples. Rose hips (Rosa canina L.) are one of the most commonly used fruits in Serbian filter tea industries. This fruit is a major source of vitamin C, carotenoids, tocopherols, unsaturated fatty acids, chlorophylls and polyphenolic compounds [1]. Among aromatic medicinal plants, yarrow (Achillea millefolium L.) is one of the most widely used, being applied for the production of one or multi-component filter teas. This plant is a good source of different bioactive ingredients, including its essential oil, flavonoids, tannins, coumarins, sterols, salicylic acid, isovaleric acid and asparagine [2]. Both rose hip and yarrow have been used for a long time in folk medicines for their high nutritional value and high concentration of health-promoting constituents. During filter teas production, the plants/fruits are cutted, milled, sived and fractionated in order to achieve an optimal particle size, ranging from 0.315 to 2.0 mm. However, during the manufacture of such product, high amounts of herbal or fruit material with a particle size lower than the size of pores of the filter bag (< 0.315 mm) are produced. This so called herbal/fruit dust or powder can reach 10 to 15% for herbs and up to 35% for fruits, resulting annually in a few tons per species per one medium filter tea producer. For these reason, developing adequate technologies that enable the valorisation of such residue/by-product represents an opportunity to convert low status wastes in valuable products. Having in mind the nature of the main bioactive compounds, in this study supercritical fluid extraction (SFE) using dense CO2 as solvent was explored to extract tocopherols and volatile compounds from rose hip and yarrow powder mixtures. Five different mixtures containing 20, 40, 60, 80 and 100% of rose hip dust were subjected to CO2 extraction (0.194 kg/h) for 5 hours at different pressures (100, 200 and 300 bar) and temperatures (40°C and 60°C). The separator conditions were 15 bar and 23°C. Extraction yield was measured after 30 min, 1, 1.5, 2, 3 and 5 hours in order to study extraction kinetics. The resulting samples were characterized in terms of global yield and analyzed by gas chromatography coupled with mass spectrometry detection (GC-MS) to detect and identify tocopherols and volatile compounds. Results showed that the global yield increased with extraction time and pressure conditions. The mixture containing 80:20, % rose hip:yarrow, resulted in the higher global yield (10.6%) when using supercritical CO2 at 300 bar and 40ºC, and in the lowest (0.3%) when applying 100 bar and 60ºC. The sample obtained from the extraction performed at 200 bar and 60ºC on 100% of rose hip revealed to be the highest source of α- and γ-tocopherol (1332.7 mg/mL). The main volatile constituents detected included camphor, eucalyptol, γ-terpinene and linalool, wherein the 20:80, % rose hip:yarrow mixture extracted at 100 bar and 40ºC yielded the highest amounts of camphor (2.0 mg/mL) and eucalyptol (1.5 mg/mL). Based on the results obtained, it is possible to conclude that SFE using CO2 as solvent enabled the selective extraction of different bioactive-rich fractions, by tuning pressure/temperature conditions and rose hip/yarrow mixtures, thus giving an important contribute for the valorisation of filter tea industry by- products.

Rose hip and yarrow bioactives; Supercritical fluid extraction

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