Abstract Peeling of Mandarin orange (Citrus suhuiensis) by enzyme aided infusion

F. Liu, A. Osman* and H.M. Ghazali

Faculty of Food Science and Biotechnology, Universiti Putra Malaysia UPM 43400 Serdang, Selangor Darul Ehsan

Received 15 August 2000 / Accepted 10 November 2000

Abstract.
Peeling is one of the most important preparatory steps in the processing of some fruits and vegetables. Pectic enzymes have been found to be able to selectively alter the albedo structure of citrus fruits and thus aid in the removal of citrus peel and the adhering albedo. Mandarin orange (Citrus suhuiensis) is a local citrus fruit that has the potential to be enzymatically peeled as it has a thin layer of peel and albedo. The objective of this study is to determinc the ease of peeling of C. suhuiensis with the aid of pectic enzymes. Five different concentrations of enzyme ranging from 0 to 0.5% v/w was applied and five different vacuum infusion durations ranging from 5 to 15 minutes were used. The oranges were first scored with eight radial lines from stem end to blossom end followed by the immersion of the oranges in the enzyme solution at 700 mm Hg, pH 4.5 and at ambient temperature (27±1oC; 60 80% RH). The time taken for complete peel removal was observed for each different enzyme concentration and for each different vacuum duration tested. There was a significant (P<0.05) difference in time taken to peel the oranges at different enzyme concentrations and at different vacuum duration. Peelzym® IV at 0.4%v/w and vacuum duration of 13 min were found to be optimal for peeling producing fruits that were relatively free of adhering albedo arid firm.

Keywords: Peeling, enzyme aided infusion, pectic enzymes, vacuum infusion, minimal processing, Mandarin Orange