Effect of freezing on rheological and textural properties of basil seed gum

Thermal treatments were effective on rheological and textural properties of hydrocolloid solution and can change functional and color properties. In this study, under optimum conditions, Basil seed gum were extracted and dried. Then, concentration of 0.2 % (w/w) of gum were prepared to determine rheological and color characteristics and concentrations of 3, 4% (w/w) for of textural properties, and then subjected to freezing treatments. Apparent viscosity and flow behavior were measured at 25 °C by Brookfield rotational viscometer and fitted with power law, casson and bingham models. Compression tests were conducted by using a Texture Analyzer and characteristics such as hardness, consistency and adhesiveness were measured. Power law model well described non-newtonian pseudoplastic behavior of Basil seed gums in all conditions. Results showed the resistency of Basil seed gum to freezing and defrosting and in the some cases, conversion of water to ice leads to an increscent in molecular association and improved their rheological and textural characteristics and with decreasing in temperature from 25 ºC to -18 ºC, viscosity increased from 0.00512 to 0.00524 pa.s (shear rate 245 s-1). The highest hardness, adhesiveness and consistency value of Basil seed gum gels (3%) were observed in sample treated at -25ºC for 24 h, 22.1 gr 22.87 gr/s and 72.74 gr/s, respectively. Therefore, Basil seed gums can be suggested as a textural and rheological modifier in formulation of foods exposed to freezing treatments.