Headspace Sulfur Dioxide and the Storage of Dried Apples

ABSTRACT A gas chromatographic technique was used to determine sulfur dioxide and carbon dioxide in the headspace of packaged apples during storage. The headspace sulfur dioxide so determined decreased more rapidly and correlated better with nonenzymatic browning of the apples than free or total sulfur dioxide. The decrease in headspace sulfur dioxide, which was not accompanied by a comparable decrease in free sulfur dioxide, was attributed to the binding of sulfite to organic components of the apple. Free sulfur dioxide was found to measure not just the inorganic sulfite, which is commonly assumed, but also bound sulfite which was rapidly released under the acid conditions. Neither free nor total sulfur dioxide in a product could be quantitatively determined from headspace gas chromatographic techniques.