The pectic polysaccharide rhamnogalacturonan II is present as a dimer in pectic populations of bilberries and black currants in muro and in juice

Rhamnogalacturonan II (RG II) can play an important role during processing of berries due to its enzyme resistance and its possible role as a pectic cross-linker. This article describes the presence of RG II in cell walls, in juice and in press cake of bilberries and black currants. RG II was identified and quantified via its diagnostic sugar residues. RG II, which was released from homogalacturonan, was probably present in its dimeric form in muro. Juice contained the free RG II dimer, while from press cake dimeric RG II was released by enzymatic degradation of homogalacturonan. A higher amount of RG II was present in juice than in press cake. During juice processing a cross-linker RG II might improve gel formation, which hinders the processability of berries. In addition, enzymes used during juice processing release dimeric RG II from pectin molecules and accumulate RG II in the juice.