Pectin changes in the pre‐cooking step of dehydrated mashed potato production

Abstract

Abstract Some in‐vivo and in‐vitro characteristics of pectin methylesterase (PME) from cell wall and whole potato tuber were determined and its role was elucidated in the pre‐cooking and cooling steps of commercial dehydrated mashed potato production. The isolated cell walls contained 16.3% anhydrogalacturonic acid with a degree of esterification (DE) of 56, and 25% of tuber total PME. Cell wall pre‐cooking in model systems resulted in a DE of 53.2. Native cell wall pectin solubilisation was much less than that of H‐cell walls devoid of metal cations. Calcium but not Mg, supplied as Ca(Mg)‐starches, retarded pectin solubilisation, while Ca‐uptake by retained pectin was high when cooling followed pre‐cooking. Texture measurements of potato slices pre‐cooked, cooled and cooked suggested a firming effect which could be attributed to Ca‐release from gelatinised starch during pre‐cooking, and stabilisation of Cabridges with free COO − groups of cell wall pectin duringcooling. The role ascribed to PME in causing firming is de‐emphasised.