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Antioxidant capacity and polyphenolic content of leaf infusions prepared from six highbush blueberry cultivars (Vaccinium corymbosum L.), one wild lowbush blueberry cultivar (Vaccinium myrtillus L.), and one commercially available mix of genotypes were determined. In order to simulate household tea preparation conditions, infusions were prepared in water heated to 95 degrees C. The dynamics of extraction of polyphenolic antioxidants were monitored over the course of 30 minutes. Extraction efficiency, quantified in terms of the total phenol (TP) content, and antioxidant capacity of infusions, evaluated by the ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging assays, were compared with cultivar type and extraction time. The 30-minute infusions exhibited the highest TP content and antioxidant capacity according to all three assays. Wild blueberry infusion had the highest TP content (1,879 mg/L gallic acid equivalents [GAE]) and FRAP values (20,050 microM). The range of TP values for 30-minute infusions was 394-1,879 mg/L GAE with a mean of 986 mg/L GAE across cultivars; FRAP values fell between 3,015 and 20,050 microM with a mean of 11,234 microM across cultivars. All 30-minute infusions exhibited significant scavenging capacity for DPPH(*) and ABTS(*+) radicals, comparable to different concentrations of catechin, gallic acid, and 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid. Overall, tested infusions showed significant reducing capacity as well as radical scavenging potential, which places blueberry leaf tea high on the list of dietary sources of antioxidants.

Abstract:In order to develop environmentally sound, energy inexpensive and well scalable drying techniques that maintain high quality of dried fruit, optimisation of integrated process (ultrasound and air-drying) in the production of dried apples was conducted. Selected quality parameters of fresh and dried apples (variety Goldparmâne) resulting from different duration of ultrasonic pre-treatment and air-drying were compared. Sugars were determined spectrophotometrically using an enzymatic method. Content of total phenols and flavonoids was determined spectrophotometrically with the Folin-Ciocalteau assay, while the antioxidant capacity was evaluated by using ABTS (2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and FRAP (Ferric Reducing/Antioxidant Power) assays. Sensory properties of dried apples were investigated according to the Quantitative Descriptive Analysis. In combination with the same air-drying conditions, prolonged ultrasound pre-treatment led to a decrease in total phenols and flavonoids, as well as in the antioxidant capacity of dried apples. Difference in drying time had no significant effect on the content of total phenols and flavonoids, as well as antioxidant capacity. The sample dried without the ultrasound pre-treatment was evaluated as the most sensory acceptable. The content of glucose and fructose correlated well with total phenols and flavonoids, as well as with antioxidant capacity of apple samples.

Caffeine-containing products have been consumed for hundreds of years for their pleasant flavor and stimulating effects. In recent years, caffeine received increasing attention in food and pharmaceutical industries, due to its pharmacological properties which comprise stimulation of the central nervous system, peripheral vasoconstriction, relaxation of the smooth muscle and myocardial stimulation. The aim of this study was to determine the content of caffeine in five types of tea (white, yellow, green, oolong, black) and two types of maté tea (green maté and roasted maté tea). The content of caffeine was determined by using four different methods: extraction with chloroform, micromethod, method with lead-acetate and high performance liquid chromatography method (HPLC-PDA). The antioxidant capacity of teas as well as of the extracted ("raw") caffeine was determined by using two methods: reactions with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical (ABTS assay) and Ferric reducing antioxidant power (FRAP assay). The content of caffeine has been associated with plant origin and growth conditions, as well as processing conditions. By applying all four methods, the highest content of caffeine was determined in white tea, whereas maté and roasted maté tea were characterised with the lowest content of caffeine. Spectrophotometric micromethod has proven to be the best alternative to the HPLC method. The highest antioxidant capacity was determined in yellow tea, while the lowest was determined in roasted maté tea. In comparison to the antioxidant capacity of teas, the antioxidant capacity of extracted ("raw") caffeine is almost negligible, and does not contribute to the overall antioxidant properties of tea.

The influence of ascorbic acid and honey addition on the total phenol (TP) content and anti-oxidant capacity of ten commercial fruit tea infusions was studied. The Folin-Ciocalteu assay was used to determine the TP content, ferric reducing anti-oxidant power assay for reducing capacity and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azino-bis(3ethylbenzothiazoline-6-sulfonic acid) diammonium salt assays for radical scavenging capacity. High pressure liquid chromatography was employed to quantify polyphenolic compounds in infusions. The addition of ascorbic acid (22.5 mg) increases the TP content as well as anti-oxidant capacity of all fruit tea infusions. The addition of honey (1.5 g) to infusions containing ascorbic acid resulted in an average 28% decrease in the TP value, and a significant average (22%) decrease in the DPPH radical scavenging capacity. Chlorogenic acid is the predominant phenolic acid in tested infusions (range: 12.86-91.55 mg/L), while epigallocatechin-gallate is the most concentrated among analyzed catechins (range: 19.26-161.41 mg/L). PRACTICAL APPLICATIONSThere are no published scientific papers characterizing polyphenolic compounds and anti-oxidant activity of infusions prepared from bagged fruit teas, although these beverages are very popular in Europe and United States where they are often taken with lemon and honey. The results reported in this study indicate that fruit tea infusions are, just like herbal teas, valuable sources of polyphenolic anti-oxidants and that beverages prepared from teas containing a substantial portion of fruit parts exhibit the best anti-oxidant properties.2 Corresponding