响应面试验优化紫胶全无氯漂白工艺及其产物性能

为避免传统含氯漂白紫胶的潜在风险，提高漂白紫胶在食品、医药等领域的使用安全性，本研究开发了紫胶的全无氯漂白工艺，采用响应面法研究了紫胶漂液质量浓度、H2O2用量、漂白温度、漂白时间、稳定剂用量等因素对漂白效果的影响，得出了紫胶全无氯漂白的最佳工艺条件：漂液中紫胶质量浓度0.08 g/mL、H2O2用量2.09 mL/g（以紫胶质量计）、漂白温度80 ℃、漂白时间7 h、稳定剂用量3.125%（以紫胶质量计）。在此基础上，通过傅里叶红外光谱、差示扫描量热、质量指标测定等方法对所得H2O2漂白胶进行了表征分析，结果发现：与次氯酸钠漂白胶和碱提紫胶相比，H2O2漂白胶分子整体结构基本一致，H2O2漂白胶热寿命、冷乙醇可溶物、酸值等指标明显提高，热乙醇不溶物、软化点等指标明显下降，颜色指数可达0.979（＜1.0），漂白胶得率为82.03%。所得无氯漂白紫胶可作为优良的食品添加剂和加工原材料。

Modeling and Optimization of Totally Chlorine-Free Bleaching Technique of Shellac Using Response Surface Methodology and Characterization of H2O2 Bleached Shellac

For the purpose of avoiding the risks arising from the application of traditional bleached shellac containing bound chlorine in the fields such as food and medicine, a totally chlorine-free (TCF) bleaching technique for shellac was developed to extend the scope of application of bleached shellac in these fields. Response surface methodology (RSM) was employed to research the influences of process parameters including ratio of shellac to bleaching solution, hydrogen peroxide (H2O2) dosage, bleaching temperature, bleaching time, stabilizer dosage on bleaching efficiency. As a result, the optimum levels of these parameters were determined as 0.08 g/mL, 2.09 mL/g (on the basis of shellac), 80 ℃, 7 h, and 3.125% (on the basis of shellac), respectively. Further, the obtained H2O2 bleached shellac was compared with NaClO bleached shellac in term of quality indicators, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) characteristics. Results showed that the molecular structure of the H2O2 bleached shellac was basically consistent with that of the NaClO bleached shellac and the alkali extracted shellac. Moreover, cold ethanol soluble substance, hot ethanol insoluble substance, thermal lifetime of the H2O2 bleached shellac were improved greatly. But the acid value was increased and the softening point was decreased significantly. The color index was 0.979 (less than 1.0) and the yield of bleached shellac was 82.03%. It was shown that TCF bleached shellac was an excellent additive and raw material for the food industry.