Study On Enzymatic Browning And Quality Control Techniques Of Fresh-cut Apples

The thesis, with four apple varieties—Fuji, Gala, Jonagold and Qinguan as test varieties, studies the browning substrates, storage temperature and packing on the quality of stored apples, and inhibiting effect of different inhibitors on enzymatic browning of fresh cut apples to find the reasons of fresh cut apples'enzymatic browning and its control.The results showed that:1. The colour and hardness values of four fresh-cut apples show declining trend. After 14 days storage, as for the colour and hardness, Fuji is the slowest variety in declining, which are decreased 9.6% and 34.56% respectively while Qinguan is the fastest one, which are declined from 77.66 to 67.09, with declining range being 13.61%. Due to colour and hardness index, Fuji is the best fresh cut variety in thin study.2. During storage, Phenolics and Polyphenol Oxidase activity of fresh-cut apples show the trend of increase first and decrease thereafter. For Phenolics, Qinguan and Jonagold is richer than Fuji and Gala; For PPO activity, Qinguan is the most active one with sharp changes.3. Different varieties have different browning substrates, of which both chlorogenic acid and Epicatechin for Gala, Fuji and Qin guan while only chlorogenic acid for Jonagold during storage.4. All 4 varieties were stored under different temperatures(2℃,6℃and 10℃), with the colour and hardness decreased to various extent. Phenolics and PPO activity increased first then decreased thereafter. The best storage temperature for the 4 varieties is 6℃, which can effectively inhibit Phenolics and PPO.5. Different packing methods result in different kinds of quality changing. Vacuum packaging is the best one in this study since colour and hardness can be well kept.6. Browning of fresh-cut apples can be inhited efficaciously by using 0.3% citric acid, 0.5% oxalic acid, 0.7% ascorbic acid, 0.7% L-cysteine and 0.007% 4-hexyl resorcinol respectively. Among these 4-hexyl resorcinol, ascorbic acid and oxalic acid are the most effective ones.7. The best quality preservation formula is 0.009% 4-hexyl resorcinol+0.8% ascorbic acid+0.5% oxalic acid, steeping 8min, store at 6℃, and the leading factor is 4-hexyl resorcinol.