Stability to thermal treatment of dipeptidyl peptidase-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 × 1 min and 121 °C × 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.