Performance comparison of decoction and ultrasound assisted extraction of Allium burdickii extracts for tie-dyeing cotton fabrics

The selection of precise variables during the extraction and colouration with natural dyes either enhances or vitiates their yield. This research study focused on the extraction of total phenolic content from Allium burdickii bulbs and their application to cotton fabric. The extraction performed using two methods, namely decoction and ultrasound-assisted extraction, was varied under three different parameters (temperature, time, and solvent type). The extracts were qualitatively and quantitatively analysed using Raman, UV-Vis spectroscopy, and Gas Chromatography-Mass Spectrometry (GC-MS). Subsequently, the extracts were applied on cotton fabric using four dyeing conditions (temperature, time, salt, and mordant concentration) and three mordanting methods (pre, meta, post), using the tie and dye method. The results confirmed the presence of compounds such as phenols, tannins, flavonoids, and saponins in the Allium burdickii bulb. The GC-MS profile revealed the presence of eight compounds in the extract. The highest TPC of 984.1 ± 5.6 mg GAE/g DW was attained using 50% glycerol, at 40 ˚C and for 60 min, using ultrasound-assisted extraction. Furthermore, Raman spectroscopic analysis confirmed the presence of functional groups, including nitroso, phenols, azo, triazenes, aromatic ethers, and alkenes. For fabric colouration, the highest exhaustion and fixation were 81.0% and 59.1%, respectively, obtained at 69.8 ˚C, 20 min, 5% mordant concentration, and 2% salt concentration conditions. This study has therefore demonstrated that the Allium burdickii bulb is a sustainable source of dye compounds suitable for use in textile colouration, and hence, can potentially substitute for the often toxic synthetic analogues.