ABSTRACT
Soy bean (Glycine max) is an important source of three natural surfactants: soylecithin, soy protein and soy saponin. Surfactant activity from soy saponin is involved in many aspects of our lives including, detergents, cosmetics, food and drinks. The purpose of this study is to produce and evaluate the qualities of herbal shampoo produced with soy bean saponin.
Soy bean was germinated for four days, and then defatted with n-hexane, using the Soxhlet apparatus. Total saponin was extracted from the defatted material using methanol as the solvent. Physicochemical properties of the saponin, including rheology, pH, surface tension, foam power, detergency, foam stability, wetting ability, haemolytic property and antimicrobial activity, were evaluated. These properties were compared with quillaja saponin. Soy saponin was used to formulate herbal shampoo and similar physicochemical properties of the products were compared with that of a commercial herbal shampoo.
The crude saponin content in the germinated defatted soy beanwas 63.4 g from a total of 1.2 kg sample. This gave a percentage yield of 5.28 %.
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The rheological property was measured as the viscosity of the extract. Soy saponin at 5 % concentration had a viscosity of 0.14 Pas while quillaja saponin at a concentration of 5 % had a viscosity of 0.28 Pas. The pH of the 5 % soy saponin was 4.8 whereas the pH of 5 % quillaja saponin was 4.3. The surface tension of water was decreased to 44.72dyn/cm by 5 % concentration of soy saponin, while quillaja saponin decreased the surface tension of water to 43.48 dyn/cm. The foam power of 5 % soy saponin at time 0 (min) was 3.47 cm, and 2.6 cm and 2.4 cm after 10 minutes and 20 minutes respectively. These gave foam stabilities of 75 % and 69 % respectively. The foam power of 5 % quillaja saponin at time 0 (min) was 6.33 cm and after 10 minutes and 20 minutes, it was 6.2 cm and 6.0 cm respectively. These gave foam stabilities of 98 % and 95 %. The detergency of 10 % soy saponin was 10.89 % while quillaja saponin had a detergency of 78.64 %. Wetting ability for 5 % soy saponin was 0.25 minute while 5 % quillaja saponin had a detergency of 2.2 minutes. At 5 % concentration, after 30 minutes exposure of soy saponin to red blood cells, 84.3 % haemolysis was observed while 5 % concentration of quillaja saponin gave a 100 % haemolysis after 30 minutes exposure. On antimicrobial property, soy saponin produced an inhibition zone diameter (IZD) of 17 mm on Bacillus substilis, 7 mm on S. typhi and no inhibition on Candida albicans and Aspergillusniger. Quillaja saponin did not produce any inhibition on both the bacteria and fungi.
In the comparison between soy saponin shampoo and commercial herbal shampoo, 5 % soy shampoo had a viscosity of 0.146 Pas while 5 % commercial herbal shampoo had a viscosity of 0.147 Pas. The pH of 5 % soy shampoo was 5.2 while the pH of the 5 % commercial shampoo was 6.63. The surface tension of 5 % soy shampoo was 38.69 compared to 37.78 for 5 % commercial herbal shampoo had. The foam power of 5 % soy shampoo was 4.10 cm and that of 5 % commercial shampoo was 16 cm. Detergency for 10 % soy shampoo was 56.19 % while 10 % commercial herbal shampoo had a detergency of 30.01 %. The foam stability of 5 % soy shampoo after 10 and 20 minutes were 85 % and 68 % respectively while that of 5 % commercial herbal shampoo after 10 and 20 minutes were 94 % and 89 % respectively. The wetting ability of 5 % soy shampoo was at 0.5 minute while that of the commercial herbal shampoo was at 0.25 minute. The soy saponin and soy shampoo with these characteristics showed an average level of acceptance.
