Abstract:Screening of non-toxic and non-sulfur anti-browning inhibitors is a hot topic. Maillard reaction products (MRPs) in fructose-lysine model system exhibited strong inhibitory effect on banana enzymatic browning in our previous study. The study mainly discussed the effect of fractionation of the products on the inhibition propertie. Ultrafiltration and dialysis were applied to divide the MRPs into three grades: MW >5000 u fraction, MW < 3500 u fraction and 3500 u < MW < 5000 u fraction. The antioxidant activities (including DPPH?scavenging ability and reducing power), chelating copper activity and the inhibitory effect on banana polyphenol oxidase were evaluated. The fraction with MW >5000 u showed the best chelating copper ion ability, followed by that with MW < 3500u. The fraction with MW <3500 u exhibited the best DPPH?scavenging ability (46.13%) and polyphenol oxidase inhibitory ability (IC50 0.089 mg/mL). Free enzyme inhibition constant (KI) and enzyme-substrate complex inhibition constant (KIs) of the obove-mentioned three parts were KI=0.297 mmol/L and KIS=1.744 mmol/L (MW >5000 u), KI =0.212 mmol/L and KIS=1.656 mmol/L (5000 u > MW >3500 u), KI =0.205 mmol/L and KIS=1.536 mmol/L (MW <3500 u). The fraction with MW <3500 u could combine free enzyme and enzyme-substrate more tightly. In conclusion, the fraction with MW <3500 u was shown to be the best for inhibiting banana enzymatic browning.
