Kinetic compensation relations for ascorbic acid degradation and pectinesterase inactivation during orange juice pasteurisations
✍ Scribed by Neşe Ülgen; Mustafa Özilgen
- Book ID
- 102432788
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 386 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
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 p H , but both kinetic functions agreed with kinetic compensation relations. An isokinetic temperature was observed for ascorbic acid degradation at p H 2*5,3*0, and 3.5 implying that the same degradation mechanism was valid at these p H values. A large deviation at p H 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 p H values. The variation of the inactivation mechanism of pectinesterase with p H was attributed to its more complex molecular structure.