Conclusion
Natural dyes provide an environmentally safe option for
coloring of food and other materials. It was found that the application of ultrasound can increase the extraction of dyes
from different parts of various plant resources. Extraction was
done using ultrasound as well as magnetic stirring methods and
the kinetics and the extraction efficiency were compared. The
reason for the improvement could be due to better leaching of
natural dye material from plant cell membranes and mass
transfer to solvent assisted by acoustic cavitation provided by
ultrasound. The results indicate that there is about 12–100%
improvement in % yield of extract obtained due to the use of
ultrasound as compared to magnetic stirring at 45 °C. Various
process parameters such as solvent system, temperature,
ultrasound power, amount of dye material etc. are interesting for
our study as future work. One would expect better extraction
efficiency with solvents like n-hexane for those dye materials
better soluble in organic solvents. But, our objective is to
develop sustainable effective process with aqueous system
without using organic solvents. Extraction efficiency may
decrease if temperature is lowered than 45 °C; however, higher
temperatures could affect plant material itself as they are
sensitive to the same. This novel technique can be employed
effectively for the extraction of coloring matter from various
plant resources even dispensing with conventional heating
requirements. This process provides effective utilization of
natural resources as eco-friendly method in current situation of
global environmental concern.