Comparison of anti-browning ability and characteristics of the fractionated Maillard reaction products with different polarities

The Maillard reaction products (MRPs) prepared from aqueous equimolar glucose with 1 M cysteine model solution when heated at 110 °C for 1 h was previously recognized as strong browning inhibitors for banana fruit. This study investigated further the anti-browning ability of the fractionated fractions with different polarity using solvent extraction following a ultra-filtration with 3.5 ku MWCO membrane and characteristized antioxidant activity including DPPH• scavenging ability and reducing power, chelating copper activity, inhibitory ability and the inhibitory constants of banana PPO. Extracts with different polarity were obtained by methanol, ethanol, n-butanol and isopropanol, which were designated as MRP(MeOH),MRP(EtOH),MRP(n-BuOH) and MRP(IPA), respectively. Application of the Lineweaver-Burk plotting showed that all MRPs were mixed-type 1 inhibitors whose Kis was larger than corresponding Ki, with Ki values ranging between 0.297 and 0.035 mg/mL MRPs. MRP(EtOH) showed the strongest anti-browning ability from the visual observation, further evidenced by its lowest Ki and IC50 in terms of the inhibition of PPO activity and DPPH• scavenging ability, with a different anti-browning mechanism vs. Na2S2O5. The strong copper chelating ability of the MRPs may account for the antioxidant ability and PPO activity inhibition to an extent. The effective anti-browning components from MRPs in glucose-cysteine model could be enriched by the combination of ultrafitration with ethanol extraction. And the extract may be applicable in food system.