Gelation of pomelo (Citrus maxima) pectin as induced by divalent ions or acidification

Effects of divalent ions and acidification on the gelation properties of pomelo pectin, having degree of esterification (DE) and molecular weight (MW) of 58% and 353 kDa, respectively, were investigated in this work. The results revealed that the gelling property of pomelo pectin could be advantageously promoted through divalent ion addition (Mg2+, Ca2+, Ba2+) or acidification. With addition of divalent ions, the gel modulus increased with increasing size of the ions, i.e. Ba2+ > Ca2+ > Mg2+. In addition, the acid-induced gelation of the studied pomelo pectin had superior gel strength and higher elastic modulus compared to commercial citrus pectin with similar degrees of esterification and molecular weight. It is considered that the distribution pattern of methyl ester groups of pomelo pectin, which are different from commercial citrus pectin, was likely responsible for these favourable dual gelation characteristics. Overall, this finding suggests that pomelo pectin is a promising food ingredient and would be potentially useful for a range of food applications that require gelling or thickening through divalent ion addition or acidification.