Sustainable ultrasonic extraction of antibacterial Basella alba fruit dye for cotton, silk, and leather

Alternative to synthetic dyes containing harmful compounds, dyes derived from natural sources are gaining popularity due to their safer and eco-friendly nature. This study focuses on extracting red dye from Basella alba fruit and optimising the extraction methods, including ultrasonic bath, ultrasonic probe, and direct heating. The extracted dye was then used for dyeing cotton, silk, and leather without needing a mordant. Furthermore, the antibacterial properties of the extracted red dye were evaluated against skin bacteria. The UV–Visible spectrophotometric analysis revealed that the maximum red colour in the methanol extract (λ_max 270 and λ_max 542 nm) was achieved at 60 °C for 30 min using the ultrasonic water bath extraction method, followed by the ultrasonic probe and direct heating methods. The FTIR spectra confirmed the presence of flavonoids, betacyanin, and gomphrenin-I in the extracted dye. The ultrasonic dyeing process at 50 °C yielded a K/s value 6.3 for the dyed cotton, silk, and leather without using a mordant. Additionally, the fatness test indicated a high grade of 0.5–1.5 for the ultrasonic dyeing method compared to other dyeing techniques. The extracted dye exhibited significant antibacterial activity against all Pseudomonas sp. after extraction in methanol, with the highest inhibition observed against Pseudomonas sp. with a MIC of 1.56 mg/ml.