速溶茶冷冻干燥最佳冻干曲线的研究

通过建立速溶茶冷冻干燥的最佳工艺,为速溶茶的工业化生产提供了良好的数据基础。研究冷冻干燥过程中绿茶提取液浓度、溶液厚度、冻干温度、干燥时间、压强对速溶茶水分含量的影响,建立了冻干曲线,确定了速溶茶冷冻干燥的最佳工艺条件:绿茶提取液浓度20%²5%,溶液厚度为10mm,冻干温度-17℃,干燥时间8.5h,压强为0.1⁰.3mmHg。      

发展冻干食品企业的问题和建议

简述了国内外冻干食品行业发展概况和中国冻干食品企业的优势，指出中国冻干食品企业建立和运行过程中存在的一些问题，分析其原因，并提出解决这些问题的具体建议。最后介绍了清华大学核能技术设计研究院在食品真空冷冻干燥方面的研究工作。     

超声预处理对真空冷冻干燥猕猴桃片品质的改善作用

目的 以“海沃德”猕猴桃为原料,采用超声预处理改善真空冷冻干燥猕猴桃片的品质。方法 分别采用不同功率（60 W,120 W,180 W,240 W,300 W）和时间（1 min,5 min,10 min,15 min,20 min）的超声波预处理猕猴桃,经真空冷冻干燥制成真空冷冻干燥猕猴桃片,分析真空冷冻干燥果片的水分含量、可溶性糖、可滴定酸、维生素C含量、水分活度、色度等指标,探讨超声预处理对真空冷冻干燥果片品质的影响规律。结果 超声功率为60 W~180 W时,真空冷冻干燥猕猴桃片的含水量提高2.51%~13.70%;超声时间为1 min~10 min时,含水量提高9.23%~11.75%。与空白相比,所有超声组的可溶性糖含量、可滴定酸含量、糖酸比均略有提高,但维生素C含量平均下降9.66%。超声预处理显著降低真空冷冻干燥猕猴桃片的水分活度,60 W~300 W超声组的水分活度下降4.29% ~20.86%;1 min~20 min超声组的真空冷冻干燥猕猴桃片水分活度下降4.91%~15.34%。所有超声组的a*值均下降,显著低于空白,其中300 W超声波使a*值下降25.08%,超声冻干果片颜色更绿。结论 猕猴桃在真空冷冻干燥加工之前,使用功率120 W ~240 W和时间1 min ~5 min超声波进行预处理,有助于改善真空冷冻干燥猕猴桃片的整体品质。     

Comparison of the effect of microwave freeze drying and microwave vacuum drying upon the process and quality characteristics of potato/banana re‐structured chips

This study investigated the drying characteristics of microwave freeze‐drying (MFD)/microwave vacuum drying (MVD) of banana/potato restructured chips of varying proportion and microwave power. The results showed the MFD drying time had a maximum one‐hour time difference between the samples treated with 2 W g^?1 and 3 W g^?1 microwave power; and the higher potato content samples have about 30 min predominance than low potato content samples in drying time and the total drying time of MVD samples was less than 60 min. For the rehydration ratio, MFD samples were far superior to the MVD samples. The MFD samples had more than 4.5 rehydration ratio. The data of the colour difference metre showed that 3 W g^?1 microwave power would make samples slightly charred. The biggest differences between the MFD and MVD chips lie in their texture and shape; the hardness of MVD samples was 30.86 N, thrice higher than MFD samples.     

淮山片真空冷冻干燥工艺的优化

目的改进淮山片真空冷冻干燥工艺的参数。方法以鲜切淮山片为材料,采用电阻法测量淮山的共晶点和共熔点温度。通过汁液流失率、复原率、中心温度和含水量检测,研究预冻和升华干燥工艺。通过正交试验和复原率、口感测定,确定淮山鲜切片的浸护处理方案。结果鲜切片在95℃水浴锅中烫漂60 s后,采用"Na Cl 5%+麦芽糊精10%+葡萄糖15%"浸护液浸泡30 min,其真空冷冻干燥产品复原率可达83.27%,复水后口感较好,产品在整个加工过程中未变色。厚度为5~6 mm的淮山鲜切片共晶点为-20℃,共熔点为-18℃,淮山片升华干燥时间耗时16 h。结论本试验建立的方法得到的淮山片复原率高,口感好,为淮山片的加工工艺提供技术支持。     

高菜真空冷冻与热风联合干燥工艺研究

研究真空冷冻（FD）与热风（AD）联合干燥腌制调味高菜,以期找到能生产优质节能的脱水腌制调味高菜的联合干燥方式。将联合干燥得到的产品分别与AD和FD干燥得到的产品进行总能耗和物理特性（包括复水比、色泽、体积密度以及产品的硬度和脆度）的比较,研究结果表明,FD20h+AD1h的产品与FD的产品在品质上无显著差异,比FD干燥方式节省能耗约33%;AD1h+FD22h比FD干燥方式节省能耗约22%,与FD的产品在色泽上有显著差异。两种联合干燥方式的产品最终湿基水分含量均达到了小于8%的要求,复水比均大于5。      

应用冻干技术加工食用菌制品

简析了食用菌快速发展形势,概述了真空冷冻干燥技术原理及产品特点,以香菇为例阐述了应用冻干技术加工食用菌制品所需的主要设备、生产工艺流程及操作要点,并对冻干食用菌产品标准进行了研究介绍。     

林蛙油真空冷冻干燥工艺研究

以林蛙油为原料,采用真空冷冻干燥技术对林蛙油进行冷冻干燥。试验结果表明,在干燥室压力20Pa、物料的预冻速度为1.5℃/min,加热温度70～80℃时的条件下,冻干林蛙油复水率可达27.39%,蛋白质43.39%。     

食品真空冷冻干燥机加热系统

介绍了新一代食品真空冷冻干燥实验机NTFD05E加热系统的结构、设计的参数及计算过程,并通过一系列冰实验得到了加热板与加热功率的关系图,从而验证了加热系统的性能要求。     

真空冷冻干燥香芋脆片生产工艺研究

以槟榔香芋为原料,研究了冻干香芋脆片的生产工艺。结果表明:采用0.2%柠檬酸做护色,3min微波熟化的真空冷冻干燥香芋片,可以保持原有的色、香、味、形。香芋片的共晶点为-13～17℃,共融点为-11～15℃;预冻温度应低于-22℃,冻干过程为60℃加热升华285min,然后升温至75℃,在此温度下解析105min;冻干过程真空度恒定为60Pa,冷阱表面温度设置为-40～-45℃,热水罐温度高于加热板温度5～10℃。     

青胡椒冷冻干燥工艺的优化

通过分析影响青胡椒冷冻干燥过程的因素,选取预冻时间、料盘装载量和干燥室真空度作为优化青胡椒冷冻干燥工艺的三个因素,并以冷冻干燥速率为指标,利用三因素三水平的响应面分析法优化了青胡椒冷冻干燥工艺条件并建立了回归模型.得到青胡椒冷冻干燥的最优条件为预冻时间6h、料盘装载量40 g、干燥室真空度20 Pa,在此条件下,冷冻干燥速率为0.05905％/h.     

保加利亚乳杆菌冷冻干燥粉不同复壮方法的比较

保加利亚乳杆菌冷冻干燥粉用１０％番茄脱脂乳培养基复壮,菌种的产酸量高,发酵活力恢复较好。     

杏鲍菇热风—真空冷冻干燥工艺优化

为了提高杏鲍菇干燥速率、品质及降低能耗,采用Design-expert软件的Box-Benhnken方法设计,探讨热风温度、热风时间、真空冷冻干燥时间对干燥速率、感官得分、复水比和氨基酸的综合影响,在该基础上由试验数据推导出二次多项式回归模型,并对干燥工艺条件进行优化。结果表明:热风干燥温度55℃、热风时间54 min,真空冷冻干燥时间11h。联合干燥耗时和耗能分别比真空冷冻干燥减少25.5%,6.3%,比热风干燥减少156.4%,63.3%。     

冷冻干燥对牛乳脂肪酸及异构体成分的影响

通过薄层色谱、气相色谱检测方法,对呼和浩特地区牛乳以及其冷冻干燥样的脂肪酸组成进行检测分析,结果新鲜牛乳和其冷冻干燥样品的饱和脂肪酸、不饱和脂肪酸以及共轭亚油酸含量极为相近。冷冻干燥对牛乳脂肪酸及异构体成分基本没有影响。     

Effect of salt and sucrose content on dielectric properties and microwave freeze drying behavior of re-structured potato slices

Potato puree was used to prepare re-structured potato slices. The effect of salt and sucrose content on microwave freeze drying (MFD) and the variation of the dielectric properties of the potato slices were studied. Results showed that the dielectric constant (ε′) and loss factor (ε″) of the potato purees decreased significantly after freezing. Both salt and sucrose addition increased ε′ and ε″ of the samples at low temperatures (−25 to −5 °C). The salt content had greater influence relative to sucrose content on dielectric properties of the samples. Sucrose addition shows insignificant influence on dielectric properties of the thawing samples; while for the salted samples, ε′ decreased gradually with increasing salt content and ε″ increased significantly with increasing salt content and temperature. MFD drying rate was significant higher after adding salt and sugar.     

免疫牛初乳真空冷冻干燥工艺条件的试验研究

利用真空冷冻干燥技术对免疫牛初乳进行冻干处理，对预冻温度、预冻速率、装液厚度、保护剂等影响冻干效果的因素进行试验研究，确定了最佳的冻干工艺参数。结果表明，装液厚度10mm，冻结终点温度-30℃，冷阱温度-45℃，真空压力15Pa．升华温度≤-5℃，解析温度≤20℃，同时添加二元保护剂：蔗糖（10g／L）与甘露醇（40g／L）。     

Analysis of operating strategies in the production of special foods in vials by freeze drying

A finite element model (FEM) with axial symmetry conditions and isoparametric elements was applied to the freeze drying of special foods in vials. The model was verified by experiments using a methyl cellulose test material. The model was used to simulate and evaluate various heating strategies in freeze drying in order to reduce drying cycles and increase process efficiency. The effect of sublimation front temperature and freeze drying periods on the process duration was analysed.