Maillard Reaction Products Inhibiting Enzymatic Browning Of Bananans Active Ingredients

Screening of non-toxic and non-sulfur anti-browning inhibitors is a hotspot. Maillard reaction products in fructose-lysine model system exhibited strong inhibitory effect on banana enzymatic browning in our previous study. The study mainly discussed the MRPs inhibitory effect on banana enzymatic browning. Ultrafiltration and dialysis was applied to fractionate the MRPs into three parts, MW>5000u fraction, MW<3500u fraction and3500u<MW<5000u fraction.The antioxidant activity (including DPPH·scavenging ability and reducing power), chelating copper activity and the inhibitory effect on banana polyphenoloxidase were then evaluated. In conclusion, MW<3500u fraction is the best one to inhibit banana enzymatic browning.Then discussed the inhibitory effect of MW<3500u fraction of MRPs extracted by methanol, Isopropanol, N-butanol and absolute ethanol on banana enzymatic browning. Also the antioxidant activity (including DPPH·scavenging ability and reducing power), chelating copper activity, the inhibitory effect on banana polyphenoloxidase and the dynamic analysis were then evaluated. MRPs in absolute ethanol showed best chelating copper ion ability, followed by MRPs in Isopropanol. While MRPs in absolute ethanol exhibited the best scavenging DPPH·ability (83.71%) and polyphenol oxidase inhibitory ability (IC50was0.061mg/mL). Free enzyme inhibition constant (K1) and enzyme-substrate complex inhibition constant (KIs) of MRPs are KI=0.037mg/mL,KIs=0.965mg/mL for absolute ethanol.MRPs in absolute ethanol could combine free enzyme and enzyme-substrate more tightly.In conclusion, MRPs in absolute ethanol is the best one to inhibit banana enzymatic browning.The MRPs in absolute ethanol was purified by silica gel column chromatography and tracked by TLC. Eluants were obtained and the inhibitory capability of each eluant against polyphenoloxidase was investigated. The results showed that the inhibition of Al was the best and stability was tested. The Al was purified by dextran gel column chromatography. Eluants were obtained and the inhibitory capability of each eluant against polyphenoloxidase was investigated.The results showed that the inhibition of D2was the best and samely stability was tested.Anion adsorption was tested and desorption solution of pH=2was the best to inhibit polyphenoloxidase.The mechanism of desorption solution of pH=2inhibition on polyphenoloxidase was studied, using enzymological kinetic method. The results showed that desorption solution of pH=2was a anti-competitive inhibitor proved by its Lineweaver-Burk plots.Desorption solution of pH=2was furtherly isolated by HPLC,then MALDI-TOF MS was detected to the single peak fractions.Paper attempts to generate an efficient and promising enzymatic browning inhibitors by the Maillard reaction for the first time, aiming at banana harvesting and storing and important issues of enzymatic browning processing. It is targeted meaningful to the development of the banana industry. Overall,the Maillard reaction products in fructose-lysine model system after ultrafiltration、dialysis and column chromatography exhibited strong oxidation and inhibited on ppo and inhibitory effect on banana enzymatic browning.