Stability to thermal treatment of dipeptidyl peptidase IV (DPP-IV) inhibitory activity of a boarfish (Capros aper) protein hydrolysate when incorporated into tomato-based products

Biofunctional peptide ingredients should retain their stability following standard processing operations in food‐based delivery vehicles. A boarfish protein hydrolysate, exhibiting anti‐diabetic activity was subjected to a range of thermal treatments following incorporation into tomato‐based soup and juice products. The dipeptidyl peptidase‐IV (DPP‐IV) inhibitory activity and peptide profile of the hydrolysate within the products were assessed before and after thermal treatment. The treatments applied had no effect on the DPP‐IV inhibitory activity or peptide profile of the protein hydrolysate. The heat‐treated (90°C x 1 min and 121°C x 42 s) juice‐fortified beverage had microbial counts within the acceptable limits for consumption when stored at 4°C for 30 days. Furthermore, the hydrolysate within the beverage products was resistant to simulated gastrointestinal digestion (SGID) regardless of whether it was heat or non‐heat treated, or stored for 30 days at 4°C. Therefore, tomato‐based beverages are suitable delivery vehicles for biofunctional peptide ingredients.