Pectic substances: From simple pectic polysaccharides to complex pectins-A new hypothetical model

► Pectins are viewed as multi-block copolymers of at least homogalacturonan and rhamnogalacturonan-I. ► It is a matter of debate as to the way in which blocks of the two polymers are interlinked. ► A first hypothetical model suggests a linear connection between homogalacturonan and the rhamnogalacturonan-I backbone. ► A challenging model proposes homogalacturonan as a side chain of rhamnogalacturonan I. ► A more complicated model in which the previous two are accounted for is here proposed.