Complex sentence: The addition of yeast to freshly pressed apples is not vital as apples contain an amount of natural yeast however most homebrewers add yeast to ensure the process works well as each variety of apple contains different amounts of yeast.
Split into simpler sentences: The addition of yeast to freshly pressed apples is not vital as apples contain an amount of natural yeast. However most homebrewers add yeast to ensure the process works well, as each variety of apple contains different amounts of yeast.