Plant-based Carotenoids: An Insightful Review of their Chemistry, Extraction and Analysis

Carotenoids are a major class of natural pigments widely found in chloroplasts or chromoplasts of plants (fruits, flowers, and vegetables), fungi, algae, and bacteria. In the past few decades, researchers have explored carotenoids from various sources and determined their structures using different analytical tools. Owing to a wide range of health benefits, carotenoid-based food supplements have emerged as an excellent option for nutraceutical and food industries. Carotenoids are a class of plant pigments involved in light absorption during photosynthesis. They also protect chlorophylls from oxidative stress and damage caused by reactive oxygen species (ROS). However, standardizing these molecules in botanicals is extremely challenging due to their poor stability against numerous environmental factors such as temperature, light, air, and oxygen. This review article describes chemistry and classification, the health benefits of various plant-based carotenoids and biosynthesis. Extraction of carotenoids plays a crucial role in standardization; various modern (green) techniques, microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) supercritical fluid extraction (SFE), have been discussed in this review. The recent concepts of extracting carotenoids using deep eutectic solvents (DES), and ionic liquid (IL) have also been covered. Along with that, the review is more focused on the identification and characterization of carotenoids in dietary botanicals, extraction techniques, sample stability, and analytical techniques for qualitative and quantitative analysis of carotenoids. Detailed information on liquid chromatographic techniques, HPLC, LC-MS, and HPTLC has been summarized in this review. In this context, the future prospects of carotenoids have also been included in this review.