KINETIC COMPENSATION RELATIONS FOR ASCORBIC-ACID DEGRADATION AND PECTINESTERASE INACTIVATION DURING ORANGE JUICE PASTEURIZATION


ULGEN N., OZILGEN M.

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, cilt.57, ss.93-100, 1991 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 57 Konu: 1
  • Basım Tarihi: 1991
  • Doi Numarası: 10.1002/jsfa.2740570111
  • Dergi Adı: JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
  • Sayfa Sayıları: ss.93-100

Özet

The thermal degradation kinetics of ascorbic acid and the inactivation kinetics of pectinesterase were studied experimentally with pH-adjusted orange juice. No simple trends were observed in variation of the kinetic parameters with pH, but both kinetic functions agreed with kinetic compensation relations. An isokinetic temperature was observed for ascorbic acid degradation at pH 2.5, 3.0, and 3.5 implying that the same degradation mechanism was valid at these pH values. A large deviation at pH 4.0 from this isokinetic reaction rate implied that the degradation mechanism was different at this pH. There was no isokinetic temperature for pectinesterase inactivation reactions, indicating that pectinesterase was inactivated by different mechanisms at different pH values. The variation of the inactivation mechanism of pectinesterase with pH was attributed to its more complex molecular structure.