Investigation of rheological behavior of Marshmallow seed (Althaea officinalis) mucilage under different temperature, concentration, and shear rate conditions

Food products could be exposed to heat treatments during manufacture, storage, and distribution chains which can affect the rheological properties of hydrocolloid solutions. Viscosity is an important factor for quality evaluation in many food products. In the current study marshmallow seed mucilage, as a potential new source of hydrocolloid, was prepared at concentrations of 4, 6, and 8 % (w/v) and subjected to heat treatments at 30, 55, and 80 °C. Afterward, time-independent rheological behaviors of examined concentrations were assessed by using a rheometer.  The findings revolved around that marshmallow seed mucilage showed a pseudoplastic behavior (n<1) as well as in the power low model. In the mentioned model the consistency coefficient (K) of all analyzed concentrations significantly has been increased at different temperatures (p≤0.01). Also, the flow behavior index value changed from 0.5092 to 0.7934 and showed a significant decrease at higher temperatures (55 and 80 °C) and also as a result of increasing in concentration. The concentrations of 4 % and 8% showed the highest temperature-dependency of consistency coefficient and flow index, respectively. In contrast, the lowest temperature dependency of consistency coefficient and flow index were detected at 6 and 4 % mucilage solution, respectively. At low concentrations, Bingham and at high concentrations Casson models, in addition, Hershel-Bulkley model best fitted with the mucilage solution.