Phytochemical properties, antioxidant activity and mineral content (Fe, Zn and Cu) in Iranian produced black tea, green tea and roselle calyces

Tea as a Source of Biologically Active Compounds in the Human Diet

“…The highest level of phenolic compounds (152.12 mg/100 mL infusion) was found in a sample of green tea originating from India (No 13), while the lowest content of these compounds was determined in a black tea infusion originating from China (No 23) and pu-erh (No 22), in which they were found at the levels of 43.38 and 46.03 mg/100 mL, respectively. The variation in polyphenol levels in various tea infusions is also indicated inter alia by studies by Almeida et al [37] and Samadi & Fard [29], who also demonstrated that the best source of these compounds were green tea leaves.…”

“…Many authors proved that polyphenols are the most important antioxidant components found in tea leaves [3,5,6,10,19]. Samadi & Fard [29] indicated that a particular antioxidant effect in tea infusions was exhibited by tannins and flavonoids, for which the correlation coefficient values specifying their relationships with antioxidant activity were statistically significant and amounted to r = 0.721 and r = 0.740, respectively. Nordin et al [42] also emphasise the significance of the method of measuring the antioxidant activity of tea infusions in determining its relationship with the level of phenolic compounds.…”

“…An infusion of tea originating from Japan, which also belonged to the green tea group, was characterised by an almost 30-fold lower content of this element (0.37 µg/100 mL, sample No 17). Most of the literature data do not indicate such a large differentiation of the teas available on the market in terms of copper levels, stating that these differences may be 2-fold [ 10 ] or 3-fold [ 29 , 31 ], although some studies conducted on teas available in Poland indicate that these differences can be 20-fold [ 30 ]. Qin & Chen [ 45 ] reported that the great variation in tea leaves available on the market in terms of the copper content may result, besides the conditions prevailing during their cultivation and harvesting, from contamination with this element due to the contact of leaves with various surfaces used during the production of tea.…”

“…Moreover, tea leaves are sold in various degrees of fineness and as blends with different ingredients. Studies conducted in many countries indicate a diversity of different types of teas available for sale due to the content of polyphenols and minerals [ 10 , 29 , 30 , 31 ]. The nutritional importance of tea leaves and their contribution to the daily intake of these compounds has rarely been analysed, and most often, studies are based on a few selected types of tea.…”

Polifenoles y actividad antioxidante de extracto acuoso de Musa acuminata Cavendish Subgroup (BANANA)

“…La mayor ventaja de este proceso de secado es que no se requiere de calentamiento durante el proceso, por tanto, no hay afectación de compuestos o materias primas termo-sensibles 7 . Es de ahí, que esta técnica de secado es ampliamente utilizada en la industria farmacéutica, alimentos y cosmética; para estabilizar productos, tales como el café, roselle, uva, fresas, arándanos, aloe vera, limoneno, canela y pitaya para sus posteriores estudios y evaluaciones de sus propiedades [8][9][10][11][12][13][14][15] .…”