Dried sweet whey was used as a complete, medium for the production of polygalacturonase by the yeast Kluveromyces fragilis. The optimum concentration for enzyme production was 0.5% (w/v) after two days at 25 degrees C. Supplementation of whey with sodium polypectate did nor increase enzyme production above the levels detected on whey alone. The concentrated enzyme was successfully used to release pectin from citrus peels and apple pomace but was unable to release pectin from sugar-beet pulp. Conditions for pectin extraction from orange peel were optimized with regard to enzyme concentration, water:peel ratio, temperature and duration of treatment. Increased liberation of pectin was achieved at 37 degrees C compared to 25 degrees C over a 24 h period. A reduction in pectin release was observed when the water:peel ratio was less than 12:1.