Influence of sodium citrate and potassium–sodium tartrate on gelation of low-methoxyl amidated pectin Original Research Article

The influence of sodium citrate and potassium–sodium tartrate on Ca2+ induced low-methoxyl amidated pectin gelation has been investigated. Dispersions with pectin concentration 1%, soluble solids (sucrose) 30% and pH 4 have been prepared. The measurements have been performed with a HAAKE VT 550 viscotester. The range of Ca2+ concentrations at which “good” gels can be formed is very narrow in cases when gels have been prepared without salt or when NaCl has been used. This range is expanded and shifted to larger Ca2+ concentration in the presence of sodium citrate and potassium–sodium tartrate. These salts “weaken” the gels (module of elasticity G and rupture stress τ0 decrease with increasing salt’s concentration) and make them more elastic (rupture strain γ0 increases). The effect of the above-mentioned salts on gel restoring after mechanical destruction (shearing) or melting has been investigated. Both salts make regelling significantly difficult in the case when the gels have been mechanically destroyed. Gels become thermoreversible (they can be melted) and their restoration after melting depends on the salt’s concentration.