Process for selective extraction of pectins from plant material by differential pH

Extraction of natural hydrocolloid carbohydrate polymers, such as pectin, from plant matter is accomplished at somewhat elevated temperature and controlled conditions of acidity/alkalinity. In many cases the plant material contains a variety of different extractables, including non-polymeric carbohydrates (sugars) in addition to the pectins. Very recently two different kinds of pectin, a calcium-sensitive pectin (CSP) and a non-calcium-sensitive pectin (NCSP), have become interesting commercially. What is described in this work is a process to selectively extract NCSP and CSP by varying the pH of the extracting solution. In a first extraction with acidic aqueous solution, a pH between 3.0 and 3.3 without addition of polyvalent salt is sufficient to extract NCSP pectin. A second extraction under stronger acid conditions (pH of about 2.0) is sufficient to extract the remaining pectin, which is primarily CSP. (C) 2000 Elsevier Science Ltd. All rights reserved.