On the stiffness of chitosan hydrochloride in acid-free aqueous solutions

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.