What is the reason why apples do not change color

The color retention of apples after cutting is usually related to variety characteristics or environmental factors, mainly involving low polyphenol oxidase activity, acidic environment inhibiting oxidation, and isolation from oxygen contact. Apple discoloration is a natural phenomenon of phenolic oxidation, but some varieties such as Red Fuji have slower oxidation due to differences in enzyme activity. Apples with high vitamin C content in acidic environments can also delay browning, and refrigeration or vacuum packaging can reduce oxygen exposure. Apples naturally contain polyphenols and oxidases, and when the flesh is exposed to air, enzymatic reactions can cause the color to darken. However, some apple varieties such as Australian green apple and red snake fruit have lower enzyme activity, and the oxidation rate after cutting is significantly slower than that of ordinary apples. High acidity varieties such as Guoguang apples can inhibit the activity of polyphenol oxidase due to their lower pH value, making them less likely to change color even when exposed to air. Measures such as sealing with cling film or soaking in lemon juice to isolate oxygen can also effectively block the oxidation reaction chain. Some merchants may use food grade antioxidants to treat sliced apples, such as soaking them in calcium ascorbate solution, which temporarily inhibits enzyme activity but is a compliant operation. It should be noted that sliced apples that are exceptionally bright and do not change color for a long time may have been treated with excessive additives such as sulfite, which poses health risks if consumed for a long time. When storing apples at home, it is recommended to prioritize physical methods such as refrigeration or vacuum sealing to delay oxidation. When apples are consumed in daily life, the degree of discoloration does not affect their nutritional value. Browning mainly results in the loss of some vitamin C, but dietary fiber and minerals are still retained. If pursuing beauty, priority can be given to varieties with dense flesh, or immediately soak in salt water for five minutes after cutting. When storing whole fruits, keep the skin dry and place them in a ventilated and cool place to maximize freshness. For pre cut fruits, it is recommended to observe whether there is any abnormal odor or sticky feeling, and avoid consuming products that may contain preservatives in violation of regulations.