Chemical Processes for the Extraction and Modification of Dietary Fiber

Abstract

Dietary fiber (DF) products are often obtained from plant sources using chemical processes. The main purpose of the extraction, purification and isolation of DFs by chemical methods is to obtain the best possible yield of DF compounds generating food ingredients with the best functionality and health benefits. Functional properties of interest include those related to gelling capacity, oil and water holding capacity, and swelling capacity, while physiological benefits relate to the production of short chain fatty acids during the microbiota fermentation of DFs, and the ones related to the presence of phenolic compounds in DFs. An understanding of chemical extraction requires knowing the DF distribution in plant tissues, the organization of DF polysaccharides in the cell wall, and the chemical interactions of these polysaccharides with other cell components. Alkaline, acid, chelating, and oxidant/bleach extractions are most often used to obtain DFs. The choice of a chemical method depends on the polysaccharide of interest. If the solution concentration, pH, time, and temperature condition of the chemical method used are extreme, the structure of the polysaccharides obtained will be modified, changing the functionality of the DFs. Novel approaches, including the use of combined methods, seek to reduce this processing severity.