Antioxidant, Antihypertensive, and Anti-inflammatory Activities of Long-Term Ripened Cheddar Cheese Water-Soluble Extract

During cheese ripening, the proteins in the cheese are broken down, and various functional peptides are produced. This research aimed to investigate the changes in peptides and their physiological activities during the long-term maturation of Cheddar cheese. Young (YC), medium (MC), and 3-year-aged extra-sharp (EC) Cheddar cheeses were extracted with water, and bioactive peptides were identified using UHPLC-HRMS (Ultra Performance Liquid Chromatography-High Resolution Mass Spectrometer). Peptides reported to have antioxidant, ACE-inhibitory, and anti-inflammatory effects were identified and evaluated in the extracts. MC and EC showed stronger antioxidant activity than YC. The ABTS (2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic) acid) inhibition rates of MC and EC were similar, but EC exhibited a higher DPPH(2,2-diphenyl-1-picrylhydrazyl) inhibition rate. The antihypertensive effect was found to increase owing to the appearance of peptides with ACE-inhibitory activity in MC and EC. qRT-PCR (quantitative real time polymerase chain reaction) and immunoblot were run to evaluate the anti-inflammatory effects. YC did not show anti-inflammatory activity, but MC and EC were shown to effectively inhibit inflammatory mRNA expression. The immunoblot results showed that EC did not inhibit IκBα phosphorylation, but had an inhibitory effect at the mRNA expression level. Overall, the peptides contained in aged Cheddar cheese were shown to have excellent antioxidant, anti-inflammatory, and antihypertensive activities, and long-term ripening appeared to have a positive effect on these activities. This is presumed to have affected not only the already identified peptides but also unknown peptides; therefore, it is expected that the discovery of bioactive peptides will be possible through additional research.