From Perception to Regulation: Frontier Advances in Structural Mechanisms, Objective Quantification, and Debittering...

The bitterness of protein hydrolysates is a critical sensory defect that severely compromises consumer acceptance and limits their application in functional foods. Bitter peptides, the primary source of this undesirable taste, often possess significant bioactivity, creating a challenging "flavor-function" duality. This conflict arises fundamentally because the structural mechanisms governing peptide-bitter taste receptors (TAS2R) interactions and the correlation between bitterness and bioactivity remain incompletely understood. Consequently, objective quantification methods lack standardization, and debittering strategies often lack precision, hindering the development of palatable functional products. This review aims to systematically analyze the structural basis of bitterness, its relationship with bioactivity, objective quantification technologies, and advanced strategies for bitter peptide removal, masking, and modification. Key findings reveal that bitterness perception is intricately linked to specific hydrophobic motifs and spatial conformation, often overlapping with bioactive features. Emerging computational resources and instruments, such as comprehensive databases, quantitative structure-activity relationship (QSAR) and machine learning models, and high-sensitivity bionic electronic tongue, offer superior high-throughput capabilities and accelerate the elucidation of peptide-TAS2R binding mechanisms compared to traditional sensory evaluation. Furthermore, distinct debittering strategies are identified: Encapsulation and masking technologies are preferred when retaining the bioactivity of functional bitter peptides is essential. Ultimately, resolving the "flavor-function" duality requires a deeper understanding of the structural mechanisms governing peptide-TAS2R binding. This fundamental insight will provide the necessary basis for standardized prediction models and the design of precision debittering technologies, thereby enabling the optimized application of bitter peptides in the development of palatable and functional protein hydrolysates.