Ellen G. White—who the Adventist Church believes was divinely inspired and that her interpretations of scripture correct inaccurate interpretations of scripture—claimed that condiments such as mustard, pepper, spices, pickles, and other things of a like character, irritate the stomach and make the blood feverish and impure.
Impurity would be equivalent to defilement, but Jesus said that nothing that enters into the stomach and is expelled can defile someone, but that which flows out from the heart is what defiles someone (Mark 7:14-20).
Paul also explains in Romans 14:1-4 that one person eats only vegetables and another doesn’t, but God accepts both people. This is also inline with what God told Noah after the flood (Genesis 9:1-3).
Ellen White’s words are extra-biblical bondage that contradict what scripture tells us. If God speaks, it is sinful to go against it. Ellen White claimed that the words in her books were barricaded by a “thus saith the Lord”, and to go against it is to insult the Spirit of God. Eating pickles isn’t a sin.