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, ∼60% in fresh cauliflower, decreased by ∼12% in samples heated at temperatures >40 °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 °C dried samples was ∼6% but increased to 12% in boiled samples and decreased in samples dried at 75 °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 °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. Keywords: Fiber; cauliflower; esterification; dehydration; hydration