脂肽类生物表面活性剂Surfactin的乳化性

Emulsifying Properties of Lipopeptide Biosurfactant Surfactin

采用白金板法对Surfactin的表面活性进行研究,并用浊度法和离心法对其乳化性进行研究。结果表明：Surfactin的临界胶束浓度为9.03×10-5 mol/L,可将水的表面张力由73.98 m N/m降至最低27.48 m N/m。在浓度为1×10-3~1.2×10-2 mol/L的NaCl溶液中,Surfactin溶液的表面张力随盐浓度升高逐渐降低并最终稳定在34 m N/m;Surfactin在121℃处理20 min后,其表面张力仍能保持在37.10 m N/m;在pH值为2~12范围内,其表面活性稳定并良好;表明Surfactin具有较强的NaCl浓度、温度、pH值的耐受性。浊度法测得Surfactin亲水亲油平衡（hydrophile lipophilic balance,HLB）值为14,对所需HLB值为12~16的油相乳化性能良好。

The activity of the lipopeptide biosurfactant surfactin was measured by Wilhelmy plate method and its emulsifying properties were investigated by turbidimetry and centrifugation. The results showed that the critical miceUe concentration （CMC） of surfactin was 9.03 × 10.5 mol/L, and it could reduce the surface tension of water from 73.98 mN/m to 27.48 mN/m. When sodium chloride was present at a concentration between 1 × 10-3 mol/L and 1.2 × 10.2 tool/L, the surface tension of surfactin solution decreased with increasing salt concentration and stabilized at 34 mN/m finally. The surface tension of surfactin after treatment at 121 ℃ for 20 rain remained at 37.10 mN/m; surface activity of surfactin revealed a good stability in the pH range of 2-12. Therefore, surfactin has a strong tolerance to salt, temperature, and pH. Hydrophile-lipophile balance （HLB） value measured by turbidimetry was 14, and surfactin had good emulsifying properties for oil phase that required an HLB value between 12 and 16.