How structural modifications of pectin affect its gelling and complexation behavior

Pectin is a plant cell wall polysaccharide that is intrinsically present in many plant-based food products, both in the plant cell particles as well as in the serum phase. In addition, extra pectin is frequently added to food products as a gelling agent and source of dietary fibre. Pectin is a polyelectrolyte with a backbone of galacturonic acid units, organized in linear and branched domains. The detailed pectin structure can be very heterogeneous even within a single cell wall. The galacturonic acid units that originally contain methylester groups can undergo deesterification thereby leaving negatively charged acid groups. Depending on the processing steps that in general include thermal treatment as well as mechanical homogenisation, various degrees and patterns of methylesterification [1,2] as well as degrees of branching can result [3]. These structural features determine the rheological properties of pectin solutions [1] as well as their gelling propensity by viscoelastic network formation [2,3,4]. Moreover, in typical food products pectin is in contact with other polysaccharides and proteins, which can result in complex formation, aggregation or phase separation. The type of interaction, phase boundaries and resulting microstructure are strongly contingent on the structural features of pectin [5]. Here, effects of processing techniques that allow to tailor pectin’s structural features will be discussed along with the relationships between these structural features and pectin’s functional properties.
[1] Moelants et al. (2013), Food and Bioprocess Technology, 6(10), 2870-2883.
[2] Ngouémazong et al. (2012), Food Hydrocolloids, 26(1), 89-98.
[3] Ngouémazong et al. (2012), Food Hydrocolloids, 26(1), 44-53.
[4] Moelants et al. (2014), Food Hydrocolloids, 36, 382-391.
[5] Antonov et al. (2018), in preparation.