Nonenzymatic browning inhibition

SO2 is not only antimicrobially active, but inhibits discoloration by blocking compounds with a reactive carbonyl group (Maillard reaction nonenzymatic browning) or by inhibiting oxidation of phenols by phenol oxidase enzymes (enzymatic browning). 

As already indicated, nonenzymatic browning is desirable in certain instances and undesirable in others. The availability of reactants and the type of conditions (temperature, pH, moisture) will determine the extent of browning. A chemical preservative often used to inhibit nonenzymatic (and enzymatic) browning is sulfur dioxide. An obvious way to prevent metal-polyphenol browning is to eliminate contact between susceptible tissues and reactive metals and use inoffensive equipment (stainless steel, glass-lined tanks, etc.)... 

Reaction of amino groups of amino acids, peptides, and proteins with carbonyl groups of carbohydrates or with tyrosine-derived quinone groups encompass changes respectively called nonenzymatic and enzymatic browning reactions (57-75). Such changes may adversely affect the appearance, taste, nutritional quality, and safety of many foods. Until recently, sodium sulfite has been used to inhibit browning... 

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