Islet amyloid polypeptide (IAPP), or amylin, has been identified as a key factor in the development of type 2 diabetes (T2D). IAPP aggregates, which form amyloid fibrils, contribute to cytotoxicity of the pancreatic β-cells, resulting in loss of function and subsequent reduction in insulin production. As a result, surviving β-cells overcompensate for this reduction of insulin production, further contributing to the loss of function because of increased stress, thus leading to insulin resistance. Endogenously, IAPP monomers function in a variety of roles; however, aggregation renders them non-functional. The use of naturally occurring compounds, including peptides and phytochemicals, has been explored as a way to mitigate or inhibit IAPP fibril formation. This review discusses the structure, endogenous roles and mechanism of IAPP fibril formation, recent advances on inhibitors of IAPP fibril formation, and new insights on the future development and application of food-derived inhibitors towards T2D management.

Pyroglutamyl (pGlu) peptides are formed from intramolecular cyclization of glutamine or glutamic acid residue at the N-terminal position of peptides. This process can occur endogenously or during processing of foods containing the peptides. Some factors such as heat, high pressure and enzymatic modifications contribute to pGlu formation. pGlu peptides are thought to have different characteristics, especially bitter and umani tastes, and thus can affect the sensory properties of foods that contain them. Moreover, some health-promoting properties have been reported for pGlu peptides, including hepatoprotective, antidepressant and anti-inflammatory activities. However, the role of pGlu residue in the peptide bioactivity is not completely established, although the hydrophobic γ-lactam ring is thought to enhance the peptide stability against degradation by gastrointestinal proteases. This review discusses the occurrence and formation of pGlu peptides in foods, their quantification, sensory and biological properties, and prospects in food applications.