Complex sentence: This style of juicer unintentionally heats the juice from friction and exposes the juice to significant amounts of air to cause oxidation; both of which may cause vitamin loss in the juice and shorten the juice's shelf life.
Split into simpler sentences: This style of juicer unintentionally heats the juice from friction and may cause some oxidation by exposing the juice to significant amounts of air. These things may cause vitamin loss in the juice and shorten the juice's shelf life.