Rheology and structure development during gelation of low-methoxyl pectin gels: the effect of sucrose

A non-isothermal kinetic model described G(I) values during gelation induced by cooling dispersions of low-methoxyl (LM) pectin + Ca(2+) and 10 and 30% (wb) sucrose at pH 4 and {2(Ca(2+))/(COO(-))} = 0.58. Two different gelation regimes, corresponding to two different temperature ranges, were observed. During the aging process, increasing the pectin concentration resulted in a significant increase in G(I) increasing the sucrose content also increased G(I). Using the plateau values of G(I) and the rubber elasticity theory, the number average molecular weight of chains between cross-links, M(c), was estimated. At the same pectin concentration, M(c) of 0% sucrose gels was greater than those of 10 and 30% sucrose gels. These results reflect the important role of the hydroxyl groups of sucrose in gel formation and that sucrose may stabilize the structure of junction zones. (C) 2001 Elsevier Science Ltd. All rights reserved.