Structure formation in sugar containing pectin gels – Influence of tartaric acid content (pH) and cooling rate on the gelation of high-methoxylated pectin

Abstract

The aim of the study was the application of a recently published method, using structuring parameters calculated from dG'/dt, for the characterisation of the pectin sugar acid gelation process. The influence of cooling rate and pH on structure formation of HM pectin gels containing 65 wt.% sucrose were investigated. The results show that the structure formation process as well as the properties of the final gels strongly depended on both parameters. With increasing cooling rates from 0.5 to 1.0 K/min the initial structuring temperature slightly decreased and the maximum structuring velocity increased. The lower the cooling rates, the firmer and more elastic were the final gels. With increasing acid content (decreasing pH from 2.5-2.0) the initial structuring temperatures were nearly constant. The final gel properties varied visibly but not systematically. Gels with the lowest and highest pH were less elastic and weaker compared to those with medium acid concentrations.

Functional properties of citric acid extracted mango peel pectin as related to its chemical structure

“…However no G 0 -G 00 cross-over was observed (no sol/gel transition) during cooling. A higher value of G 0 compared to G 00 was already reported in literature for other HMPs even at high temperature (Kastner et al, 2014;L€ ofgren et al, 2005). Cooling with the rate of~1 C/min as it is commonly suggested in literature (Almrhag et al, 2012;Kastner et al, 2014), increased both moduli as a result of increased number of junction zones that is believed to be stabilized by hydrogen bonds and also by hydrophobic interactions between the methyl ester groups (Lopes da Silva & Gonçalves, 1994).…”

“…A higher value of G 0 compared to G 00 was already reported in literature for other HMPs even at high temperature (Kastner et al, 2014;L€ ofgren et al, 2005). Cooling with the rate of~1 C/min as it is commonly suggested in literature (Almrhag et al, 2012;Kastner et al, 2014), increased both moduli as a result of increased number of junction zones that is believed to be stabilized by hydrogen bonds and also by hydrophobic interactions between the methyl ester groups (Lopes da Silva & Gonçalves, 1994). Unlike commercial citrus pectin (DM ¼ 63%, usually low concentration of NS) for which G 0 and G 00 in the vicinity of G 0 -G 00 cross-over changed dramatically during 60 min at 20 C (Lopes da Silva & Gonçalves, 1994), no changes were observed for the values of G 0 and G 00 of the mixture from MPP at 20 C for almost 2 h after the cooling step indicating that no further rearrangement or formation of junctions zones occurred during that prolonged time (results not shown).…”

“…The mixture was heated for 10 min on stirring plate to dissolve the sugar. The solution was boiled for another 10 min to assist gel formation (Brejnholt, 2010;Kastner et al, 2014;Vithanage, Grimson, Wills, Harrison, & Smith, 2010). The mixtures were reweighed and the amount of evaporated demineralized water was added.…”

The impact of rhamnogalacturonan-I side chain monosaccharides on the rheological properties of citrus pectin

“…6A). Then IST describes the start of the gelling, where no gel is formed, but initial hydrophobic interactions start occurring, and thus gel elasticity starts increasing (Kastner et al, 2014). This value decreased to a similar extent when reduction in Araf and Galp occurred, with values of 52 C, 39 C and 40 C for Or, OrG and OrA, respectively.…”

Influence of pH on solution and solid-state properties of citrus pectin

“…A higher degree of esterification causes more rapid gel setting at lower soluble solids than pectin with a lower degree of esterification. (Kastner et al, 2014) The gelling behavior is also influenced by pH change. As increasing pH, depolymerization or chain cleavage occurs and results in rapid loss of viscosity and gelling properties while LMP indicate better stability at this conditions.…”