Enzymatic modifications of pectins and the impact on their rheological properties

The interaction of new pectin-modifying enzymes (Novo) with three commercial pectins and their chemically de- O-acetylated and de-esterified counterparts is investigated. The study focuses not only on the ability of these pectins to act as substrates, but also on the consequences of modifications on their rheology and molecular weight. We present results that demonstrate that highly specific modifications of pectins are attainable. Enzymatic alterations of the side chain regions yielded polymers having a significantly lower viscosity, in the absence of calcium. In contrast, the viscosity of calcium-free pectin samples was increased after de-esterification of the backbone with pectin methylesterase. If the rheological properties of de-methoxylated pectin were studied in the presence of calcium, G′-values were increased 35-fold and the gel-like properties were markedly enhanced.These preliminary experiments emphasise the high application potential of enzyme-treated pectins. However, further investigations are required to custom-tailor pectins for utilisation in various food or other products.