Quality analysis and authentication of nutraceuticals using near IR (NIR) spectroscopy: A comprehensive review of novel trends and applications

Quality control (QC) of nutraceuticals has always been a challenging task due to their complex nature and wide sources of variability. As a green, fast, and nondestructive tool that requires no sample preparation, near infrared spectroscopy (NIRS) is increasingly employed in this field. Advances in NIRS instrumentation and interpretation posed for its increasing application in nutraceutical QC. In this review, NIRS application in nutraceuticals QC with special emphasis on novel trends from targeted and untargeted approaches is presented. The targeted approach comprises applications made towards analysis of relevant metabolite classes in nutraceuticals while the untargeted approach comprises discrimination of geographical origin, cultivars, varieties and fingerprinting of nutraceuticals. The value of NIRS application and its novel trends in nutraceuticals QC are critically assessed disclosing advantages and limitations with emphasis on areas demanding future advancements. NIRS and its novel trends are outstanding analytical tools compared to other spectroscopic tools for QC of nutraceuticals from targeted and untargeted viewpoints. The review manifests the value of complementing NIRS with other vibrational technique (MIR) or a totally different analytical platform. In addition, hyperspectral imaging and portable devices applications in nutraceutical QC are less explored with proposed suggestions to overcome current limitations presented. Spectral simulation and 2D-COS techniques require broader application to prompt their advantages in nutraceuticals QC.