Enzymatic modifications of pectins and the impact on their rheological properties

The interaction of new pectin-modifying enzymes (Novo) with three commercia l pectins and their chemically de-O-acetylated and de-esterified counterpar ts is investigated. The study focuses not only on the ability of these pect ins to act as substrates, but also on the consequences of modifications on their theology and molecular weight. We present results that demonstrate th at highly specific modifications of pectins are attainable. Enzymatic alter ations of the side chain regions yielded polymers having a significantly lo wer viscosity, in the absence of calcium. In contrast, the viscosity of cal cium-free pectin samples was increased after de-esterification of the backb one with pectin methylesterase. If the theological properties of de-methoxy lated pectin were studied in the presence of calcium, G-values were increas ed 35-fold and the gel-like properties were markedly enhanced. These prelim inary experiments emphasise the high application potential of enzyme-treate d pectins. However, further investigations are required to custom-tailor pe ctins for utilisation in various food or other products. (C) 2002 Elsevier Science Ltd. All rights reserved.