Optimization of Ultrasound-assisted extraction of Quince seed mucilage using Response Surface Methodology

Nowadays, different methods of hydrocolloid extraction has been studied and the effect of these methods has been investigated on functional properties of these hydrocolloids. According to these studies, it has been found that different variables has influence on hydrocolloids properties such as temperature, water to seed ratio, pH, salt concentration and extraction time. “Quince” tree is local tree in Asia and widely grow in north of Iran. The fruit of this tree has seeds which have extractable mucilage on its outer surface. Extraction of “Quince” seeds mucilage always was done by conventional methods and there is limited information about using new technology such as ultrasound on extraction. The objective of present study is to assess the effect of extraction by ultra sound wave in addition to some variables such as temperature and pH on extraction yield and rheological properties of extracted mucilage. In order to obtain optimum extraction yield and apparent viscosity, optimization of “Quince” seed mucilage extraction was done using “Response Surface Methodology” and “Central Composite Rotational Design” and Optimum operating condition of extraction was predicted.
“Quince” seeds were obtained from Gilan ecotype. In order to determine the effect of different parameters on yield (%) and apparent viscosity (mPa.s) of extracted mucilage, three independent variables including temperature (25–55ºC), ultra-sonication time (3–10 min), and pH (6–8) were investigated. Response Surface Method was used to design Experiments. Apparent viscosity of mucilage were measured by rotational viscometer Brookfield at 50 RPM in constant temperature 25ºC. Using regression analysis, a second-order polynomial model was developed for each response. Chemical composition of extracted mucilage was determined using AOAC standard methods.
among investigated variables, temperature and ultra-sonication time had significant effect on extraction yield and viscosity while pH was not significant (p “Quince” seed mucilage showed a non-Newtonian and shear thinning (pseudoplastic) behavior. Extraction yield and apparent viscosity has affected by some extraction parameters such as temperature and ultra-sonication time so optimum yield and viscosity can access with determining suitable conditions of mucilage extraction.