Should you add kiwifruit to your cereal? – An investigation of bioactive peptides produced with kiwifruit extract : A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science at Lincoln University

Abstract

Oat is a popular cereal food which contains high amounts of beneficial compounds shown to exert positive effects on human health. It is notable for its relatively high protein content. Actinidin is a protease found in kiwifruit which has strong digestive properties. This study investigated if actinidin could be combined with oat to break down the endogenous oat proteins and generate peptides with bioactive properties, thus increasing their potential health effects. Kiwifruit extract was combined with oat at 37 C for four hours to allow for maximum release of soluble protein into the samples. After the heat treatment step the samples were put through an in vitro digestion system. Changes in antioxidant activity were measured using total phenolic concentration (TPC), ferric reducing antioxidant power (FRAP), and angiotensin-converting-enzyme (ACE) inhibition assays. The Combined sample was not significantly different (p > 0.05) from the Kiwifruit Extract only sample for any compound analysed. However, the decrease in TPC, and increase in ACE was significantly greater (p < 0.05) in the Combined sample than the Rolled Oat only sample. Protein and peptide gels showed no difference between samples. Overall there was no evidence of significant changes to beneficial effects of the oat, as caused by the addition of actinidin. The addition of oat appeared to have a slight beneficial effect on the enzymatic activity and antioxidant content of kiwifruit. Future work investigating other bioactive compounds that are known be present in the oat is reccommended to gain a better understanding of the effect of actinidin on oat proteins.