Some possible glucose/glycine browning intermediates and their reactions with sulphites

In near neutral aldose/glycine systems, hydroxymethylfurfural is not an important intermediate in browning. The possible intermediates studied all require glycine (or a similar compound) for rapid browning; glucose is not required. In retarding browning, bisulphites do not react directly with any of the intermediates tested. Bisulphite addition to unsaturated aldehydes (such as 3,4‐unsaturated 3,4‐dideoxyhexosone), derived from a cycle of reactions involving glucose dehydration, would explain the observed results. Conversion of bisulphite to sugar sulphates or to elemental sulphur does not appear to be important in retarding non‐enzymic browning under these pH conditions.