Optimization of Variables for Aqueous Extraction of Gum from <i>Grewia mollis</i> Powder

Abstract

Grewia gum is a polysaccharide derived from the inner stem bark of the edible plant Grewia mollis . Juss (family Tiliaceae). It is a savanna shrub that grows wildly but is usually cultivated in Nigeria and Northern part of Cameroon. The main goal of the present study was to investigate the effect of aqueous extraction conditions on the extraction yield and physicochemical properties of the Grewia mollis . The studied aqueous extraction variables were water/powder (W/P) ratio (10 : 1–80 : 1 w/p), temperature (25.0–85.0 ∘ C), time (1–3 h), and pH (4.0–10.0). The results indicated that the aqueous extraction variables exhibited the least significant (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>P</mml:mi><mml:mo>&lt;</mml:mo><mml:mn fontstyle="italic">0.05</mml:mn></mml:math>) effect on the yield and the viscosity of the gum. The result shows that the ratio of extraction is the main factor affecting the extraction of gum. The optimized extraction condition for higher viscosity was at the powder/water ratio of 1 : 55.4, pH of 7, time of 1 h, and temperature of 50 ∘ C. However, the optimized extraction condition for higher yield was at the powder/water ratio of 1 : 80, pH of 4, time of 3 h, and temperature of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:msup><mml:mrow><mml:mn>73</mml:mn></mml:mrow><mml:mo>∘</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:mrow></mml:math>.