Natural dyes and pigments make the market for the pharmaceutical, food and textile industries over various synthetic dyes due to their eco-friendly nature and impactful health benefits, as well as cosmeceutical importance. Since they are obtained from natural sources, they contribute to the upliftment of local biodiversity. Despite these advantages, natural pigments face various challenges in their colour fastness properties due to factors like photo-degradation, thermal degradation, microbial degradation, pH sensitivity, oxidation, harvesting or growing conditions and also the shortcomings of the ancient extraction methods. The purpose of this paper would be to evaluate the stability challenges of natural pigments and illustrate the various methods and approaches to improve their stability.
This review describes the natural sources of various dyes and pigments and the common stability issues and the factors causing them. Furthermore, the present work enlightens the techniques that stabilize the colour fastness properties and improve colour stability, including co-pigmentation, complex formation, microencapsulation, addition of bio-mordant and antioxidants. Each of these techniques has been evaluated by diverse groups of scientists and applied for stabilization of natural source-based colours.
Among the techniques applied, use of nanotechnology, bio-mordanting and co-pigmentation has been found to improve the stability of pigments significantly. Future studies on the application of such methods and the commercial production of pigments may be required.
To the best of the authors’ knowledge, this review work focusing on techniques to improve the stability of naturally sourced pigments has been presented for the first time. It compiles and compares all the novel techniques to improve the stability of natural pigments and thus is significantly beneficial for researchers in this field.
