Effect of micronization on functional properties of the water caltrop (Trapa taiwanensis Nakai) pericarp

The aim of this study was to investigate the effect of micronization on the functional properties of the water caltrop (Trapa taiwanensis Nakai) pericarp (WCP). Three different micronization treatments were carried out, including wet milling (WM), freeze-dried milling (FDM) and hot-air dried milling (HDM). Seven fractions of micro-sized WCP were obtained for each treatment, using hammer and ball milling, consecutively. The ball milling treatment of WCP resulted in an increase of hydration properties (solubility, water-holding capacities, and swelling capacity) and oil-holding capacities due to the redistribution of fibre components from insoluble to soluble fractions. The cation-exchange capacity of WCP increased significantly with decreases in particle size after micronization by ball milling. The findings suggested that different micronization treatments could improve functional properties of the fibre components of WCP, which provide a good source of dietary fibre in food applications.