Tissue Strength

• Mere minutes after peeling an apple, the apple begins to change colors.Jupiterimages/Photos.com/Getty Images
  
  The density of the apple's skin is the apple's primary defense against bruising. Once the skin is initially damaged or broken, the apple becomes more susceptible to bruising, regardless of the environment in which the apple is kept. The apple skin's pliability and resistance to breakage only exists if the proper hydration and temperature levels are maintained.
  
  

Hydration Levels

• An apple's turgor, or hydration, level can greatly determine its likelihood of bruising. Apples that have a higher turgor level are more likely to bruise, as the increased hydration makes the fruit significantly more sensitive to impact than a slightly less hydrated apple would be. Think of it this way: if you have a half filled water balloon and you throw it at someone, the low level of water reduces the chances that the balloon will break upon impact. On the other hand, if you overfill a water balloon, the balloon becomes so sensitive to impact that you must be careful even handling the balloon, lest it break in your hands and soak you instead of your intended target.
  
  

Temperature Levels

• Apples can be kept in cool, but not freezing conditions.Stockbyte/Stockbyte/Getty Images
  
  Another issue that affects the bruising of an apple is the temperature level in which the apples are stored. Apples kept in colder conditions are more susceptible to bruising. The reason for this is that the cold temperature freezes the moisture in the apple, causing the skin to become very brittle. If anything comes into contact with an apple in this condition, the skin is very likely to break and bruising will occur.
  
  

Handling Condition of the Apples

• You can bruise apples if you accidentally drop them.Jupiterimages/liquidlibrary/Getty Images
  
  Apples subjected to harsh impact situations are definitely going to end up with bruising on them. When apples are collected, processed, shipped and delivered, each stage of the handling process provides a new opportunity for the apples to become bruised. During a normal handling process, apples are dropped from heights and at speeds that increase the chance of the apple bruising. Lack of cushioning and piling of apples on top of each other can also lead to the apples bruising. Human interactions with the apple can lead to bruising, whether the handling of the apples is careless or the apples are dropped by accident.