AbstractsBiology & Animal Science

The antioxidant mechanism of roasted coffee to inhibit oxidation in beef is attributed to its metal chelating and free radical scavenging properties, but interaction with beef proteins may be another antioxidant mechanism. The purpose of this study was to investigate antioxidant mechanism of coffee on oxidation inhibition in beef muscle through the interaction with beef proteins. Sarcoplasmic (SP) and myofibrillar (MP) proteins extracted from top round beef muscle were treated with lyophilized coffee brew (0 - 160 ??g/mL protein) and incubated with lipid oxidation (LOX) products (malonaldehyde/MDA and saturated aldehyde compounds/C5-C9) at 4??C. The bound MDA and saturated aldehydes per g protein after incubation were determined over 9 days. Fluorescence, myoglobin (Mb) absorption spectra, and docking were performed to determine the interaction behavior of coffee on beef proteins. Moreover, metmyoglobin (MetMb) formation and thiol oxidation were also observed to determine the effect of coffee on protein oxidation (POX). The results showed that coffee increased ability to bind MDA and nonanal when interacting with SP. Specifically, coffee interacted at surface of Mb in SP via hydrophilic interaction, and bound to aldehydes via hydrophobic interaction. Coffee did not increase thiol oxidation and MetMb formation. The finding help elucidate the antioxidant mechanism of coffee when added to beef and suggest that roasted coffee potentially inhibits LOX while does not cause POX.