| Pea is considered to be an important grain crops, pea fermentation broth (PFB) could strongly inhibit browning of fruits and vegetables. PFB has great potential to be used as a natural source of antioxidants to reduce the negative effects of browning in fruits and vegetables processing. In this study, the inhibitory effect of PFB on polyphenol oxidase (PPO) and enzymatic browning of potato has been studied. Inhibitory mechanism of PFB, stability of effective components in PFB, the chemical compositions of PFB, effective anti-browning ingredients of PFB were researched.The important results were obtained as follows:1. The inhibitory effect of pea fermentation broth (PFB) on polyphenol oxidase had been studied. The results demonstrated that the inhibition effect of the enzyme by PFB was concentration-dependent. The inhibition rate of PPO rapidly increased when the concentration of PFB increased.160 mg/mL of PFB could totally inhibit the activity of potato PPO, as well as 0.2 mg/mL Sodium bisulfate and 0.4 mg/mL VC. PFB could delay the browning of potato PPO, and it also could increase the lag time of potato PPO.Kinetic analyses showed that the PFB used in this experiment was irreversible inhibitor of the PPO from potato. PFB not only has a significant inhibitory effect on potato PPO but also has a certain inhibitory effect on varieties of fruits and vegetables.2. The chemical constituents of the pea fermentation broth were studied with chemical pre-trial system method. The result showed that the pea fermentation broth contained amounts of chemical components, such as amino acid, proteins, polysaccharides and glycosides, phenols, organic acid, flavonoids, saponins, etc. Systematic Pre-experiment also showed that the fermentation didn’t contain alkaloids, fats, steroids and terpenoids. The results suggested that the effective anti-browning ingredients in PFB may be one or several components of amino acids, proteins, polysaccharides, saponins, organic acids, polyphenols, flavonoid.3. This experiment investigated the stability of pea fermentation broth under various conditions. The results of the stability test indicated that there was not distinctly different between the inhibitory effect of PFB on potato PPO before and after heat. And it was also stable to acid and alkalis, Ultraviolet light. This indicated that the effective anti-browning ingredients in pea fermentation broth were very stable and would not easily affected by external conditions.4. The effective anti-browning ingredients in pea fermentation broth were analysised preliminarily. The results demonstrated that the effective anti-browning ingredients in PFB were not easy to proteolysis, indicating that the effective anti-browning ingredients were not protein substances. Crude polysaccharide in the fermentation broth was almost no inhibitory effect on potato PPO. None- polysaccharide fermentation broth could strongly inhibit the activity of potato PPO as with the effect of the control. The efficiencies of different extraction methods to obtain the effective anti-browning ingredients were compared. The results showed that the effective anti-browning ingredients in PFB were likely to be one or several polar substances. The molecular weight of anti-browning ingredients in pea fermentation broth was investigated. The results demonstrated that the molecular weight of the anti-browning ingredients was under 1000 u.5. First PFB was purified by macroporous resin, then Sephadex G-15 gel chromatography was used for secongary purification, and four fractions—PFB1～ PFB4 were obtained. The effective anti-browning components of PFB2 were analyzed by UV, HPLC, HPLC-MS. The results demonstrated that the effective anti-browning components have a characteristic absorption peak at 264nm. By means of HPLC and HPLC-MS, we found that the molecular weight of the mainly effective component was 548. The structure of the substance was needed to further investigate. |
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