Black Chickpea: Nutritional Architecture, Seed-Coat Phytochemistry, Techno-Functional Properties, and Processing Challenges

Black chickpea is a subgroup of desi chickpeas characterized by its black-colored seeds. The crude protein content in evaluated accessions of black chickpea ranged from 19.8-25.4%, which is rich in lysine 11.2%). Black chickpea also contains several essential minerals, such as calcium (370–490 mg/100 g), iron (3.8–8.2 mg/100 g), and zinc (1.8–5.4 mg/100 g). Condensed tannins (0.58–7.91 mg/g) and flavonoids (taxifolin, biochanin A) are concentrated in the pigmented seed coat. Black chickpea exhibits a high radical-scavenging capacity of up to 2417 μmol Trolox Equivalents/100 g, primarily localized in insoluble-bound fractions. From a technological perspective, protein isolates have maximum alkaline solubility (>79% at pH 10–11) and high oil absorption capacity (445%). However, tannin cross-linking in the seed coat increases the least gelation concentration to 14-16% as opposed to 10% in kabuli isolates. Although bioprocessing (germination, fermentation) reduces recalcitrant phytates and improves in vitro digestibility, utilization is limited due to dark flour discoloration, beany off-flavors, and scalability trade-offs associated with processing. Additionally, the alleged cardiometabolic benefits of black chickpea are mostly speculative based on in vitro preclinical models as opposed to robust human clinical trials. This review provides a scientific basis for breeding, sustainable agriculture, and utilization of functional foods.