Black Garlic: Evolution of the Chemical Composition and Broad Biological Activities

Black garlic, a product obtained from fresh garlic (Allium sativum L.) under specific temperature and humidity conditions, has garnered significant scientific attention due to its enhanced organoleptic qualities and superior health-promoting properties compared to the fresh product. The Maillard reaction, alongside other chemical transformations, converts pungent organosulfur compounds like allicin into stable, highly bioactive compounds such as S-allyl-l-cysteine and S-allylmercaptocysteine, while also increasing the levels of polyphenols and other potent antioxidants. This review provides a comprehensive overview of black garlic, detailing the impact of its unique ripening process on its chemical composition, encompassing changes in sugars, proteins, amino acids, lipids, vitamins, minerals, and organic acids. We explore how variations in temperature and humidity during production influence the final product quality attributes and bioactive compound profiles. Furthermore, we extensively discuss the diverse biological activities of black garlic and its key constituents, including significant antioxidant, anti-inflammatory, anticancer, immunostimulatory, antiallergic, hepatoprotective, antidiabetic, and antiobesity effects. By synthesizing current research, this review highlights black garlic potential as a functional food and a source of therapeutic agents, while also emphasizing the need for standardized production methods to ensure consistent quality and maximize its health benefits.