Characterization of tea produced from the leaves of two varieties of Ipomoea batatas

摘要

This study consists of analyzing the phytochemical composition, antioxidant activity and sensory properties of green tea infusions of two varieties of Ipomea batatas and two commercial green teas. Green tea was obtained after withering, fixing, rolling, and drying of I. batatas leaves. Phytochemical screening was performed using characteristic tests, total phenol, flavonoid and proanthocyanidin contents, as well as antioxidant activity were performed using spectrophotometric assays. The hedonic testwas used to assess sensory properties. The results obtained demonstrated the presence of free quinones, flavonoids, saponins, tannins, alkaloids and phenols in all the samples analyzed. Variation ranges of flavonoids, phenolics and proanthocyanidins were7.24±0.11 to 11.67±0.18 mg CE/g, 10.95±0.09 to 46.63±0.93 mg GAE/g, and 3.04±0.16 to 3.17±0.08 mg CE/g, respectively. These last two chemical groups were higher in the infusion of brand 1 green tea, which was correlated with its high antioxidant activity measured using the PAP test (PAP value=80.96±0.49 mg BHTE/g). The infusion of green tea of I. batatas variety 1 exhibited the lowest antioxidant activity measured using the DPPH tests (IC_(50)=5.08±0.04 mg/ml), FRAP (FRAP value=12.16±0.20 mg BHTE/g) and PAP (PAP value=33.31±0.01 mg BHTE/g). The sensory analysis revealed that brand 2 green tea presented the highest scores for appearance and colour and there was no significant difference in odour, taste and overall acceptability among all teasamples. The results of this study showed that green tea infusion produced from I. batatas could be used in the development of green tea, natural source of antioxidants and they had interesting potential to prevent non-communicable diseases.