| 摘要: |
| 【目的】分析微波真空冷冻干燥（microwave vacuum freeze drying，MFD）工艺对蛋清粉凝胶特性的影响，为制备高品质的高凝胶性蛋清粉提供参考。【方法】以鸡蛋清为原料，以凝胶硬度为指标，分析微波功率、真空度、装载量对MFD蛋清粉凝胶硬度的影响，通过响应面优化试验确定MFD制备蛋清粉的最佳工艺条件。以喷雾干燥（spray drying，SD）和真空冷冻干燥（freeze drying，FD）为对照，对MFD制备样品的凝胶特性（质构、失水率和色差等指标）进行对比分析，并通过傅里叶红外光谱（Fourier transform infrared spectroscopy，FTIR）和扫描电镜（scanning electron microscopy，SEM）分析其微观结构的变化。【结果】MFD蛋清粉最佳干燥工艺条件为：微波功率503 W、真空度150 Pa、装载量195.2 g，该条件下凝胶硬度为（393.159±5.230） g。MFD蛋清粉的凝胶硬度较FD蛋清粉提高了16.24%，较SD蛋清粉降低了19.82%，但其凝胶黏结力、咀嚼性和回弹性较其他2种蛋清粉样品增大；失水率由大到小表现为FD>MFD>SD，且三者之间差异显著。FD和MFD蛋清粉凝胶的色泽无显著差异，但与SD蛋清粉相比，两者的明度（L*值）显著增加，红度（a*值）和黄度（b*值）显著降低，因此更易被消费者接受。FTIR结果显示，α-螺旋与β-折叠含量之比从小到大依次为MFD
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| 关键词: 蛋清粉 干燥条件 凝胶特性 微波真空冷冻干燥 微观结构 |
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| 基金项目:国家自然科学基金项目（U1704114）；河南省重点攻关项目（182102110346）；河南省重大科技专项（161100110900，161100110600-2，161100110700-2，161100110800-06） |
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| Optimization of microwave vacuum freeze drying conditions of egg white powder and analysis of gel characteristics |
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LIU Lili,ZHANG Mengjun,DAI Xiaoning,et al
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| Abstract: |
| 【Objective】The effects of microwave vacuum freeze drying (MFD) process on properties of egg white powder gel were analyzed to provide support for preparation of high quality egg white powder with high gelatinous properties.【Method】Egg white was used as raw material and gel hardness was used as index.The influence of microwave power,vacuum degree and loading capacity on gel hardness of MFD egg white powder was analyzed.The optimum technological conditions for preparing egg white powder by MFD were determined by response surface optimization.Taking spray drying (SD) and freeze drying (FD) as controls,gel characteristics (texture,water loss rate,chromatic aberration and other indicators) of samples prepared by MFD were comparatively analyzed,and changes of its microstructure were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).【Result】The optimum drying conditions of MFD egg white powder were microwave power of 503 W,vacuum degree of 150 Pa,and loading capacity of 195.2 g.The gel hardness was (393.159±5.230) g under optimal conditions.The gel hardness of MFD egg white powder was 16.24% higher than that of FD and 19.82% lower than that of SD.However,its cohesive force,chewiness and resilience of MFD egg white powder were larger than those of other samples.The water loss rate was in the decreasing order of FD>MFD>SD with significant differences.There was no significant difference in color between FD and MFD egg white gel.Compared with SD egg white powder,the L* value of FD and MFD was significantly increased,while a* value and b* values were significantly decreased.Therefore,FD and MFD were more acceptable to consumers.FTIR results showed that the ratios of α-helix structure to β-folded structure were in the increasing order of MFD
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| Key words: egg white powder dry conditions gel properties microwave vacuum freeze drying microstructure |
