Grape pomace extract as a colorant for textile printing applications

The growing need to reduce the negative impact on the environment and human health, as well as to meet the growing demand for eco-friendly textiles, has led to the development of environmentally friendly printing techniques and the use of natural dyes in the textile industry. Grape pomace is important waste material in winemaking, and has been extensively studied for its potential as a source of compounds with biological properties, especially anthocyanins, pigments responsible for the red, purple, and blue colors in grapes. The aim of this paper was to examine the potential use of natural dye extracted from grape pomace of domestic cultivar crna Mirisavka (GPCM) in preparation of printing paste with alginate, citric acid, and tannic acid for printing on cotton fabric. Special focus was placed to achieve process color magenta, by adjusting the pH value of the extract obtained. The natural dye from GPCM was extracted using maceration with 80% methanol, followed by sonication to enhance the yield of bioactive compounds. GPCM extract demonstrated significant antioxidant activity measured by FRAP, DPPH, and ABTS+ tests, and moderate antibacterial activity against Staphylococcus aureus and Escherichia coli. The pH-dependent stability of anthocyanins in GPCM extract was examined, demonstrating a magenta tone at acidic pH (pH 2-4) and color degradation at higher pH values. Cotton fabric printed with two different concentrations of GPCM extract (100 mg/L and 50 mg/L) showed good antioxidant and antibacterial activity. Based on the obtained results, it can be concluded that GPCM extract can be an environmentally friendly solution for the development of antibacterial and antioxidant textiles, with potential application in the production of protective clothing in healthcare institutions, as well as for the production of decorative home textiles, for the production of children's toys and textiles for packaging.