Extraction and characterization of mucilage in Opuntia spp.

The cactus pear (Opuntia ficus indica) mucilage is an interesting ingredient for the food industry because of its viscosity properties. We studied the conditions for the extraction and precipitation of the plants mucilage. Extraction conditions were: pad/water ratios (1:51:7), extraction temperature, (40 +/- 2 and 16 +/- 2 degrees C) and extraction time (4, 8 and 16 h). For the precipitation of the mucilage two types of alcohol (ethanol and isopropyl alcohol) and two water/alcohol ratios (1:3 and 1:4) were used. No differences were found in any of the measured variables among the different extraction or precipitation methods. The average mucilage yield after drying was 1.48% based on fresh weight (f.w.) and 19.4% based on dry weight (d.w.). The dried mucilage had in average 5.6% moisture; 7.3% protein; 37.3% ash; 1.14% nitrogen; 9.86% calcium and 1.55% of potassium. The colour analysis showed a high L* value and the chromatic co-ordinates were in the yellow-greenish spectrum. The use of isopropyl alcohol is recommended in ratio 1:3, since its commercial value is lower in comparison with ethanol. (c) 2006 Elsevier Ltd. All rights reserved.