Journal
FOOD CHEMISTRY
Volume 92, Issue 2, Pages 311-323Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.foodchem.2004.07.026
Keywords
enzymatic browning; marula fruit; polyphenol oxidase; peroxidase; phase separation
Ask authors/readers for more resources
Marula fruit, native to sub-Saharan Africa, is of growing commercially importance. Polyphenol oxidase (PPO) and peroxidase from the fruit were partially purified by a combination of temperature induced phase separation in Triton X-114, DEAE-ion exchange and Sephadex G100 gel filtration. PPO activity was purified 58-fold with 75% recovery while the purification factor for peroxidase was 19% with 25% recovery. The enzymes were characterised for enzyme concentration-reaction rate relationship, thermal stability, pH activity and stability, molecular weight, isoelectric point (pI) and kinetic parameters. PPO and peroxidase shared the same molecular weight (71 kDa) and pI (5.43). Thermal deactivation curves were bi-phasic for both activities. Peroxidase displayed maximal activity at pH 4.0 with ABTS (2,2'-azino-(bis-3-ethylbenzthiazoline-6-sulfonic acid)) and a Km of 1.77 mM for hydrogen peroxide. The pH optimum for PPO was 7.0 with catechol. Marula PPO had Km values of 1.41, 1.43, 3.73 and 4.99 mM for catechin, 4-methyleatechol, 3,4-dihydroxyphenylpropanoic acid (DHPPA) and catechol, respectively. (c) 2004 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available