Low molecular weight fucoidan prepared by fucoidanase degradation – A promising browning inhibitor

Low molecular weight (MW) fucoidans have been proved with excellent tyrosinase inhibitory activity, which may proposed as a potential anti-browning ingredient for fruit and vegetable fresh-keeping agent. This study was conducted to obtain a low MW fucoidan fraction with high tyrosinase inhibitory capacity from Laminaria japonica crude fucoidan by fucoidanase degradation and to preliminary explore its type of tyrosinase inhibition and the application in browning inhibition of fresh-cut fruit. Firstly, the wild fucoidan-degrading strain, Flavobacteriaceae RC2-3, was mutated by UV irradiation and the fucoidanase production was improved by 40.5%. Fucoidan, which degraded by purified fucoidanase for 2 h, presented favourable tyrosinase inhibitory ability and were then separated by ultrafiltration. The fucoidan fraction with MW below 5 kDa (FF5) demonstrated the best tyrosinase inhibitory effect and shown obvious browning inhibition of fresh-cut apple slices. The inhibitory kinetics revealed that FF5 was a quite effectively competitive inhibitor of tyrosinase. The results of this study suggested that FF5 could be used as a promising browning inhibitor in the preservation of fruits and vegetables.