Investigation on Physicochemical and Rheological Properties of Malva Leaves Gum (Malva Neglecta)

Gums are polysaccharide components with high molecular weight that easily suspend in water and are dispersed under suitable conditions. They are used as stabilizer, texture modifier, gelling agent, thickener and emulsifier. The aim of this study was to determine the properties of the new Malva leaf’s gum.
The gum was isolated from the leaf of Malva neglecta plant by warm-water extraction. Purification was carried out by barium complexion. Purified gum was evaluated in terms of physicochemical properties. Furthermore, rheological properties of extracted gum were evaluated in shear rate at the range of 0.1–1000 s-1 with Brookfield viscometer and flow behavior and effect of temperature and gum concentration on the viscosity was evaluated.
The Purified gum contained 8.12±0.43% moisture, 77.04± 0.83% carbohydrate, 8.56± 0.62% protein, 2.49± 0.3% ash and 5.33± 0.29% uronic acid. Among the rheological models, power law model appropriately described the behavior of the gum. Arrhenius model was also properly applied to evaluate and describe the relation between gum viscosity and temperature. Three model's power, exponential and polynomial were used to evaluate the effect of gum concentration on the apparent viscosity in the shear rate of 10 s-1.
According to shear thinning behavior, Malva gum can be used in food industry. Extracted gum showed higher sensitivity to temperature at higher levels of gum concentration and power law model was selected as the best model to assess the effect of gum concentration on the viscosity.