摘要：

INTRODUCTION L-Ascorbic acid (ASA) is widely used in manufacture of many food products for the purpose mainly to inhibit browning, but sometimes discoloration due to ASA is observed in lemon1) or orange2) juice of high ASA content. Though some extensive studies3,4) have been reported on the subject, browning of ASA is still unknown in many respects. It is generally accepted that reductones play an important role in nonenzymic browning reaction such as sugar amino reaction, but their exact role in the reaction is still unknown. Since ASA is a typical aci-reductone,5) it is worth while to investigate the browning reaction of ASA to elucidate the mechanism of non-enzymic browning reaction. In the presence of oxygen, ASA is known to degrade to dehydro-L-ascorbic acid (DHA) in the first step. Therefore studies on browning of DHA or mixtures of ASA and DHA are needed to elucidate browning of ASA. As for browning of DHA described in some literatures, there are some discrepancies which are undoubtedly due to the impurity of DHA used. DHA used in previous studies was

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