Natural pink dyestuff extraction from torch ginger flowers via an oven drying method

Abstract

The environmental and health implications of textile dyeing processes have led to increased interest in natural dyes as sustainable and ecofriendly substitutes. In this study, Etlingera elatior (torch ginger) flowers (TGFs) in the pink shade were extracted into natural dyestuffs via freeze and oven drying techniques. Freeze drying was performed by cooling the extracted torch petals with addition of NaCl at −85°C for 48 h, while oven drying was conducted at 40, 50, and 60°C for 48 h. Physical and chemical properties of the dyestuff were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and zeta potential. To evaluate the color strength and lightfastness of the extracted natural dye, silk yarns were dyed with the TGF dyestuffs with alum and slaked lime as mordants. The color strength (K/S) and colorfastness of the dyed silk yarns were measured using CIE Lab along with other additional unique characteristics such as anti-UV and antibacterial properties under AATCC standards. We observed that dyeing silk yarn with the extracted dyestuff via oven drying technique at 40°C and slaked lime as a mordant exhibited the highest color strength (K/S) values and excellent washing fastness (rating 4–5). The dyed yarn also inherited >99.96% antibacterial property against Staphylococcus aureus and very good UV protection property under UVA irradiation (rating 4).