The flesh near the centers of my apples has a glassy appearance. Why?
Water core is probably responsible for the glassy appearance to the apples. Water core is a physiological disorder that develops before harvest and is characterized by translucent, water-soaked areas in the flesh. These water-soaked areas commonly develop near the core, but in severe cases, can radiate out to the skin. Fruit with water core are edible and have a sweeter flavor, but their storage life is reduced. Environmental conditions, such as hot days followed by cool nights, may increase the occurrence of water core.
Water core most often occurs when fruit are harvested at an advanced stage of maturity. To prevent water core, harvest apples as soon as the fruit reach minimum maturity. Immediately store the apples. Optimum storage conditions for apples are a temperature of 30 to 32 degrees Fahrenheit and a relative humidity between 90 and 95 percent. Mild cases of water core may disappear in storage.