The interest in berries from food manufacturers is huge, which is explained by good organoleptic characteristics and high biological activity of berries. One way to preserve the properties of berries throughout the year is to obtain extracts. Determining the conditions and type of optimal extraction technology to obtain biologically active substances from plant materials is an important stage in the production of new natural preventive additives. The aim of this work is to study the chemical composition and antioxidant activity of blueberry extracts (Vaccinium myrtillus L.) obtained by various methods: maceration, ultrasonic and microwave extraction. The use of ultrasonic extraction as a method of intensifying the process of extracting biologically active compounds from blueberries is very effective. This proves an almost 2-fold increase in the flavonoid content in the extracts. However, the content of anthocyanins in the extracts of blueberries is not the highest for ultrasonic extraction (a decrease by 3.3 times compared with maceration), in all likelihood due to the instability of this class of compounds in this type of processing. Among the extracts of blueberries obtained by three technologies (maceration, microwave and ultrasound treatment), it is the ultrasound extract that has the highest antioxidant activity (9.5±0.1 mg/cm3, 18.18 mmol±0.24 Fe2+/1 kg, 58.6%), determined by three methods: DPPH method, FRAP method, method for assessing antioxidant properties using a model system with linoleic acid. Ultrasonic extraction was chosen as a technology for obtaining a concentrated blueberry extract.

A reliable source of increased intake of vitamins and biologically active substances are not only berries and fruits, but also herbs. This article is devoted to the analysis of plant samples for antioxidant activity. The objects of study were selected herbs and flowering woody plants of the Samara region: small-leaved linden color (Tilia cordata), medicinal sage (Salvia officinalis L.), medicinal clover (Melilоtus officinalis), currant leaf (Folium Ribes nigrum), wild strawberry (Fragum folium silvam), grapes (Vitis labrusca). Plant material collected in the phase of mass flowering. Aqueous alcoholic extracts (1 : 1 ratio) were obtained from the samples at 37 °C for 2 hours. Anti-radical activity was tested using the free radical DPPH (2,2-diphenyl-1-pilkrilgidrazil), restoring force the FRAP method (Ferric Reduction Antioxidant Power), antioxidant activity in the linoleic acid system and the content of phenols, flavonoids. Analyzing the results obtained in this work, we can conclude about the presence of antioxidant properties. The leader in anti-radical activity and regenerative power was a currant leaf, a high content of phenols has linden color, the maximum content of flavonoids was also recorded in a currant leaf.

One of the most frequently consumed sources of natural antioxidants is tea. High content of phenolic substances in it, makes it an excellent functional drink. At present, interest in tea is great not only as an independent drink, but also as a raw material for the production of tea extracts. The study was conducted on extracts obtained from samples of leaf tea of foreign and Russian origin in the following parameters: the content of soluble solids in tea extracts; total content of phenolic substances; total content of flavonoids; total content of tannins; antiradical activity by the DPPH method; restoring force by the method of FRAP. During the study of tea species, different in the way of processing and in the region of origin, it was determined that the leader among the presented teas is the white tea of Chinese origin, which has the highest antiradical activity and the highest content of tannins. Comparing green tea from China and Russia, it can be concluded that the content of individual groups of substances varies slightly against the background of slightly higher anti-radical activity of Chinese tea. In the group of black teas, the Indian "Harmutti" tea is in the lead by the results of the test, significantly exceeding tea from the Krasnodar Territory by anti-radical activity and the total content of phenolic substances. Thus, promising types of tea for the prevention of diseases (diabetes, atherosclerosis, hypertension, Alzheimer's disease), arising as a consequence of oxidative stress, are tea white Chinese and green tea Krasnodar.

Phenolic compounds, flavonoids, anti-radical activity, and restorative power are found in walnuts, pecans, almonds, hazelnuts, hazelnuts, cashews, macadamia, and peanuts. The highest content of phenolic substances in the studied nuts was found in walnuts (536.6 mg of gallic acid per 100 g of dry matter), pistachios (512.9 mg of gallic acid per 100 g of dry matter) and pecans (377.6 mg of gallic acid per 100 g of dry matter). Wild hazel contains 1.4 times more phenolic substances compared to hazelnuts and 4.2 times more flavonoids. In this work, a method was used to determine the concentration of the extract at which 50% of the free radical is bound by the 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical. The antioxidant activity was found only in the extract of pecans, pistachios, walnuts, and hazelnuts. No antiradical activity was detected in the remaining extracts. The restorative power of all the studied extracts is mainly, to a small extent. Of the studied extracts, peanut and pistachio extracts showed the greatest restoring power. Hazelnut and pecan extracts also exhibit greater restorative power than other extracts studied.

Сравнительные исследования методов извлечения биологически активных веществ с антиоксидантными свойствами из косточек винограда ( Vitis vinifera L. )