THE EFFECT OF CITRATE ANIONS ON THE KINETICS OF CUPRIC ION CATALYZED OXIDATION OF ASCORBIC-ACID


SAHBAZ F., SOMER G.

FOOD CHEMISTRY, cilt.47, sa.4, ss.345-349, 1993 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 47 Konu: 4
  • Basım Tarihi: 1993
  • Doi Numarası: 10.1016/0308-8146(93)90175-f
  • Dergi Adı: FOOD CHEMISTRY
  • Sayfa Sayıları: ss.345-349

Özet

The kinetics of uncatalysed and Cu(II) ion-catalysed oxidation of ascorbic acid by molecular oxygen in the presence of citric acid and its anions were studied at 25-degrees-C. In the pH range investigated (2.5-6.0), the rate of cupric ion-catalysed oxidation was found to be first order with respect to ascorbic acid. The observed effects of pH and cupric ion concentration on the reaction rate suggests a mechanism which may involve the formation of a transition complex between monoascorbate ion and Cu(II)-citrate chelate. The catalytic ability is in the order Cu(II) > H3CiCu+ > HCiCu- > CiCu-2. Hydrogen peroxide was also detected during the reaction.