The effect of high pressure homogenization on pectin: Importance of pectin source and pH

Pectin is a common, heterogeneous, and structurally complex polysaccharide present in plant cell walls that is naturally present in staple foods and commonly used in the food and biomedical industry. Pectin is known to be sensitive to process induced chemical changes that can result in various effects on its functionality. This worked aimed at better understanding the effects of high pressure homogenization (HPH), an emerging technology that can be used to influence rheological/textural properties and reduce the microbial activity of liquid food systems in a continuous process, on pectin. Our results show that the previously suggested depolymerization of pectin is dependent on its source, most likely due to the presence of neutral sugar (NS) side chains. While citrus pectin (poor in NS) was depolymerized by HPH, apple pectin (richer in NS and having a more compact structure) was not. The depolymerization only occurred to pectins above a specific Mw threshold, resulting in the possibility of utilization of this method for the production of a more uniform pectin. Additionally, an effect for pH was noticed. At pH 6.3, the HPH induced conformational changes resulted in a more compact structure (for both pectins), while at pH 4.4 no conformational changes were noticed. HPH did not result in changes in the degree of methoxylation of both pectins and also no change in the amount of reducing sugars was noted.