Effects of amidation and/or methylesterification of pectin on aroma release at different calcium concentration

Four different types of low methoxyl pectins (LMPs) were prepared via amidation and methylesterification to investigate the release of 14 aroma compounds from different pectin gel systems at different calcium concentration. The release of aroma compounds was determined using static headspace gas chromatography analysis. Amidation and amidation combined by methylesterification increased aroma release from LMP gels compared to the non-treated ones at diverse calcium concentration, except amidated LMP at 0.09% calcium. On the other hand, methylesterified LMP reduced the release of most aroma compounds at 0.03-0.09% calcium concentration. Furthermore, treatment with pectin methylesterase increased the release of aroma compounds from amidated pectin but reduced their release from nonamidated pectin. Comparison of the release of a series of esters with different numbers of carbon atoms revealed increased release of compounds with up to six carbons, and then a decrease of those with up to ten in LMP, amidated LMP, and amidated and methylesterified pectin gel systems.