Ultrasound assisted extraction of food colorants: Principle, mechanism, extraction technique and applications: A review on recent progress

The growing usage of natural food colourings has fuelled the search for novel methods for their extraction from various sources. Due to its process benefits such as high yield and quality, short extraction periods, use of low temperatures, ultrasound-assisted extraction (UAE) has been studied as a new green strategy. Plant pigments are a rich source of bioactive constituents that could be incorporated in the production of novel functional food additives and an alternative to synthetic substances that can improve the health of consumers. Anthocyanins act as antioxidants, to eliminate the free radicals produced in the body. It is believed that carotenoids offer health benefits through reducing the risk factors associated with certain malignancies and eye diseases. Functions of chlorophyll include aiding in the battle against cancer, facilitating the liver's detoxification process, accelerating the healing of wounds, promoting healthy digestion and weight control, and preserving healthy skin. Betalains contains high soluble fibre content, which effectively lower the levels of LDL cholesterol. In this review, the recent developments about the UAE of various colouring pigments such as anthocyanin, carotenoids, chlorophyll and betalains from different sources and influence of UAE parameters on the extraction yield of colouring pigments were detailed.