Abstract
The optimization of the extraction of natural antioxidants from white tea has fostered intensive research. This study has investigated the effects of ethanol-water mixtures, temperature and time on the extraction of polyphenols and antioxidant components from white tea. The response surface methodology was applied to identify the best extraction conditions. The best conditions to maximize the extraction of total polyphenols were: ethanol, 50%, for 47.5 min. Although the yield of polyphenols was optimal at 65 °C, the maximum antioxidant capacity was achieved with an extraction temperature of 90 °C. This study has identified the optimal conditions for the extraction of tea liquor with the best antioxidant properties. Epigallocatechin gallate, epicatechin gallate, epigallocatechin and epicatechin were extracted from white tea at concentrations up to 29.6 ± 10.6, 5.40 ± 2.09, 5.04 ± 0.20 and 2.48 ± 1.10 mg/100 g.
Highlights
Natural antioxidants are increasingly appreciated by consumers due to both their inherent positive effects [1] and to the possibility of using them as a source of natural additives to replace synthetic ones [2,3,4]
The experimental design was carried out to evaluate the effects of temperature, solvent concentration and time on antioxidant extraction
Salah et al [39] reported that the relative antioxidant activity of the tea catechins assessed by the Trolox equivalent antioxidant capacity (TEAC) assay was in the order epicatechin gallate (ECG) > epigallocatechin gallate (EGCG) > EGC > EC, so it is clear that
Summary
Natural antioxidants are increasingly appreciated by consumers due to both their inherent positive effects [1] and to the possibility of using them as a source of natural additives to replace synthetic ones [2,3,4]. The antioxidant capacity of white tea extracts, which can be measured in vitro by various assays, including oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) or diphenylpicrylhydrazyl assay (DPPH), among others [22,23,24]. This activity is linked to the high content of flavan-3-ols, which are known as catechins. The response surface methodology (RSM) was used for the optimization of extraction variables (time, temperature and % of ethanol) to enhance the yield of polyphenols and antioxidant activity [15,26,27]
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