Abstract

The effect of different treatment conditions (pressure, treatment time, and temperature), as well as composition of pectin solution (Pectin, Ca⁺⁺ ion and sugar concentration, pH) on gel formation of two types of low methoxylpectins were investigated. The results have shown that with increasing pressure, time or temperature during high hydrostatic pressure (HHP) treatment, the gel hardness increased continuously. Up to 2.5 times higher gel hardness could be achieved after HHP treatment (550 MPa, 35°C, 10 min, and 2% pectin) compared to untreated sample. Higher sugar concentration in pectin solution (about 30 to 60%) resulted in drastically increasing the gel hardness for untreated as well as HHP treated samples but the overall gel hardness was, in the case of HHP treated samples, distinctly higher than the untreated. Similar results could be observed if the Ca⁺⁺ ion concentration increased up to 90 mg/g pectin. Increasing the pH of pectin solution from pH = 3.4 to 5.6 decreased the gel hardness in the case of untreated as well as HHP treated samples. The results of this study confirmed that it is possible to produce firm gel from low methoxylpectin at temperature of £35°C using high hydrostatic pressure technique.

Key words: Low methoxylpectin, gels, high hydrostatic pressure.