Effects of heat treatment and dehydration on properties of cauliflower fiber.

The effects of heat treatment and dehydration on fiber structure and hydration properties, using cauliflower floret/curd and stem tissues, have been investigated. No major changes in fiber composition resulted from sample treatments, but the degree of esterification of pectic polysaccharides, approximately 60% in fresh cauliflower, decreased by approximately 12% in samples heated at temperatures >40 degrees C. Enzymic activity was considered to be responsible, through pectin methyl esterase activity. De-esterification was temperature and moisture sensitive. Hydration properties were also affected by processing conditions. The solubility of nonstarch polysaccharides in fresh, freeze-dried, and 40 degrees C dried samples was approximately 6% but increased to 12% in boiled samples and decreased in samples dried at 75 degrees C. Similar behavior occurred for swelling and water retention capacity (WRC), with swelling and WRC highest for boiled samples and lowest for samples dried at 75 degrees C. Hence, a decrease in de-esterification was not directly responsible for changes in hydration properties. The results demonstrate the importance of processing history on functional properties and on the preparation of fiber-rich ingredients for successful incorporation into foods.