UV protection effect of cotton dyed with Flos Sophorae (Sophora Japonica L.) extracted with acid hydrolysis

Flos Sophorae extract was hydrolyzed using a mixed solution of methanol, HCl, and water to convert rutin to quercetin for the purpose of enhancing the UV protective effect of dyed cotton. Relative yield (%) of quercetin in the hydrolyzed extract was determined by the percent ratio of the absorbance of untreated Flos Sophorae extract at 359 nm to the absorbance of hydrolyzed extract at 370–371 nm. Quercetin yield was 93.09% when 1 M HCl was applied and 52.03% when 0.5 M HCl was applied, both with 60 min reaction time. The latter was applied in dyeing cotton with the dyebath containing hydrolyzed Flos Sophorae extract and water by 50:50 or 75:25 ratio. By dyeing with hydrolyzed Flos Sophorae extract the UPF value of cotton was enhanced to 13.80 indicating 92.76% blockage of the UV rays as opposed to 84.78% blockage by the same fabric without Flos Sophorae dyeing. The present method could produce a light-weight summer cotton with yellow color which could provide a moderate UV protection for daily summer attire.