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Protein hydrolysis is a process used in the food industry to generate bioactive peptides of low molecular weight and with additional health benefits, such as antihypertensive, antidiabetic, and antioxidant properties that are often associated with their content on hydrophobic amino acids. This results in an increased bitterness of the products, making them less desirable for their use in food formulations. This review summarizes the main dietary sources of bitter bioactive peptides, including methods to determine their bitterness, such as the Q-values and electronic tongue; and the main factors and mechanisms underlying the bitterness of these compounds. The main strategies currently used to improve the taste and oral delivery of bioactive peptides are also discussed together with the main advantages and drawbacks of each technique. Debittering and masking techniques are reported in detail, including active carbon treatments, alcohol extraction, isoelectric precipitation, chromatographic methods, and additional hydrolytic processes. Other masking or blocking techniques, including the use of inhibitors, such as modified starch, taurine, glycine, and polyphosphates, as well as chemical modifications, such as amination, deamination, acetylation, or cross-linking were also discussed. The findings of this work highlight encapsulation as a highly effective method for masking the bitter taste and promoting the bioactivity of peptides compared to other traditional debittering and masking processes. In conclusion, the article suggests that advanced encapsulation technologies can serve as an effective means to mitigate the bitterness associated with bioactive peptides, while simultaneously preserving their biological activity, increasing their viability in the development of functional foods and pharmaceuticals. [ABSTRACT FROM AUTHOR]

The cholecystokinin-2 receptor (CCK2R) is a G protein-coupled receptor (GPCR) that is expressed in peripheral tissues and the central nervous system and constitutes a promising target for drug development in several diseases, such as gastrointestinal cancer. The search for ligands of this receptor over the past years mainly resulted in the discovery of a set of distinct synthetic small molecule chemicals. Here, we carried out a pharmacological screening of cyclotide-containing plant extracts using HEK293 cells transiently-expressing mouse CCK2R, and inositol phosphate (IP1) production as a readout. Our data demonstrated that cyclotide-enriched plant extracts from Oldenlandia affinis, Viola tricolor and Carapichea ipecacuanha activate the CCK2R as measured by the production of IP1. These findings prompted the isolation of a representative cyclotide, namely caripe 11 from C. ipecacuanha for detailed pharmacological analysis. Caripe 11 is a partial agonist of the CCK2R (Emax = 71%) with a moderate potency of 8.5 µM, in comparison to the endogenous full agonist cholecystokinin-8 (CCK-8; EC50 = 11.5 nM). The partial agonism of caripe 11 is further characterized by an increase on basal activity (at low concentrations) and a dextral-shift of the potency of CCK-8 (at higher concentrations) following its co-incubation with the cyclotide. Therefore, cyclotides such as caripe 11 may be explored in the future for the design and development of cyclotide-based ligands or imaging probes targeting the CCK2R and related peptide GPCRs. [ABSTRACT FROM AUTHOR]