真空冷冻干燥技术在三七加工中的应用

介绍了真空冷冻干燥的基本原理,并据三七的特点,探讨三七真空冷冻干燥的工艺流程及特点,简要分析了三七冷冻干燥的前景。     

膜分离技术与真空冷冻干燥技术在茶加工上的应用

膜分离技术与真空冷冻干燥技术在速溶茶加工上应用的原理及优越性，以及速溶茶的广阔前景。     

国内真空冻干设备及冻干食品的考察报告

介绍了我国冻干设备和冻干食品的发展现状及展望了新疆冻干食品的发展前景。     

真空冻干设备及冻干食品的考察报告

简要介绍了我国冻干设备和冻干食品的发展现状及发展新疆冻干食品的前景。     

提高真空冷冻干燥速率的研究

随着科学技术和经济的发展 ,人们的饮食结构和消费观念的变化 ,加快了冻干食品的发展。然而 ,真空冷冻干燥的速率较低 ,冻干时间一般较长 ,操作费用较高 ,导致冻干食品的生产成本较高 ,从而限制了冻干食品的发展。所以 ,如何采取措施 ,提高干燥速率 ,降低成本 ,对冻干食品的发展具有重要的意义。本文从冷冻干燥的理论和操作的全过程分析了影响冻干速率的各种因素 ,研究了提高干燥速率的各种措施 ,以供实际操作时参考     

Effects of Spray Drying and Freeze Drying on the Properties of Protein Isolate from Rice Dreg Protein

This work was done to investigate the effects of different drying methods in the preparation of rice protein isolates (RPIs), as the understanding could provide useful information regarding applications of plant proteins in the food industry. RPI from rice dreg protein, a cheap by-product from the production of rice syrups, was extracted using an alkali solution along with isoelectric precipitation, and subsequently dried by freeze drying (FD-RPI) or spray drying (SD-RPI). The differences in biochemical, physical, and structural characteristics were observed for the dried proteins. SD-RPI had higher protein solubility and emulsifying activity at the pH values between 5 and 11, with higher foaming capacities (127.08?±?2.25 % compared to 118.83?±?2.71 %) than FD-RPI. However, FD-RPI had larger mean diameter (2,114.2?±?79.6 nm compared to 490.4?±?44.8 nm of SD-RPI), higher water/oil holding capacity (p?<?0.05), and thermal stability. In addition, FD-RPI contained more β-turn structures (43.04 % compared to 25.81 %), and less β-sheet and random coils than SD-RPI, indicating that the more compact and ordered conformations of FD-RPI might be related to their physicochemical and functional properties. The choice of drying method could significantly influence physicochemical and conformational properties of RPIs, consequently determining their specific functional properties. The understanding of drying effects on their properties could assist in selecting the appropriate drying method to optimize the utilization of RPIs in the food industry.     

热风和微波结合干燥荔枝加工工艺研究

本试验对以荔枝鲜果为原料,通过热风干燥和微波干燥相结合制作荔枝干果的加工工艺进行了研究。研究结果表明,荔枝鲜果经预处理后,用70℃的热风干燥至50％的水分含量,再以240g/kW的微波处理量进行干燥,所得荔枝干果品质最佳。采用PA＆PE复合包装袋加脱氧剂的包装方法,其保质效果最好,贮藏期在9个月以上。     

Ultrafiltration and Reverse Osmosis Recovery of Limonene from Citrus Processing Waste Streams

Commercial ultrafiltration (UF) and reverse osmosis (RO) membranes were used to concentrate the terpene, limonene, present in cold pressed oil centrifuge effluent and molasses evaporator condensate. UF membrane rejections were 78–97% for mixtures with initial limonene concentrations from 0.04–0.6%v/v. RO membrane rejection of limonene ranged from 87–99% for feed streams containing 0.06–0.23% limonene. Initial membrane flux rates for centrifuge effluents were in the range 10–100 kg/m²/hr. Evaporator condensate fluxes were higher, 25–400, while pure water rates ranged from 25 (RO) to 1000 kg/m²/hr (UF). Contact with limonene adversely affected membrane flux rates in decreasing order of severity: polysulfone > cellulose acetate > teflon-type.     

最大升华速率下酸乳冷冻干燥过程的模拟、控制及生产率优化

本文采用过程分解的方法研究在干燥各阶段使浓缩酸乳升华速率最大所需要的操作参数。假设浓缩酸乳冷冻干燥过程中冻结层温度Ti由冻结终点温度Tf经过每K温度上升到熔点温度T0，以冻结层温度Ti时升华速率最大为目标，以纯冰在Ti时最大升华速率计算模型为基础，推导出冻结浓缩酸乳在Ti时以最大速率升华所允许的最大物料厚度δiy的计算模型及对应的升华时间tiy的计算模型：以物质能量平衡原理推导出Ti时最大速率升华所需的搁板温度Tis的计算模型。以∑δiy、∑tiy作为浓缩酸乳冷冻干燥实验的物料厚度、总干燥时间，以相应干燥时间的Tis计算值作为实验过程中的搁板温度进行浓缩酸乳冷冻干燥实验。实验表明：预冻终温-30、-28、-26℃，物料厚度19、13、8mm的浓缩酸乳在预测干燥周期21．5、10．2、5．2h时，延长预测时间的10％继续干燥，获得的制品含水量3％～5％，能达到冻干食品含水量要求。     

海藻糖对乳酸菌冷冻干燥保护机理的研究

研究了海藻糖对乳酸菌冷冻干燥的保护机理。用DSC方法测定海藻糖浓度和加热速度对海藻糖玻璃化转变温度的影响,海藻糖的浓度和升温速度对玻璃化转变温度都有影响,但浓度变化对海藻糖的玻璃化转变温度影响不显著。测定了几种糖类(10%)的玻璃化转变温度,发现海藻糖具有最高的玻璃化转变温度(-27.79℃),蔗糖为-31.43℃,葡萄糖为-42.90℃。通过对海藻糖和卵磷脂的混合物的红外光谱的分析结果表明,海藻糖能够和细胞膜成分形成氢键作用,取代水的位置,保护细胞膜的稳定性,为"水替代"假定提供支持。     

冻干酸奶粉的速溶性及发酵性研究

本文采用冻干法生产酸奶粉,对其速溶性和发酵性等进行了研究,结果发现:冻干酸奶粉具有良好的速溶性,其静置时的润湿下沉时间为76s,最适冲调条件为4～5倍45℃的温水。冻干酸奶粉的活菌数和菌活力分别为7.53×10~8cfu/g和85℉,将冻干酸奶粉作为发酵剂生产酸奶时,3.5hr即凝固且所得酸奶品质良好。     

长白山笃斯越橘中花色苷不同提取工艺的研究

比较不同方法对长白山笃斯越橘中花色苷提取产物的影响,优选最佳提取工艺方法。以长白山笃斯越橘为原料,分别采用酸性乙醇法、超声提取法及微波提取法提取花色苷,对超声提取及微波提取进行三因素三水平正交试验分析,以确定最佳提取工艺。通过结果比较分析,以微波提取工艺结果最佳,在微波提取功率为100 W,提取时间为60 s,料液比为1∶5(g/mL)的微波提取条件下,花色苷的产量达到了0.402 mg/g(湿重),使得花色苷提取产量较酸性乙醇法及微波提取法得到了显著提高。     

Downstream Processing of the Hydrolysate from Cassava Fibrous Waste in the Production of Confectioner's Syrup

The acid hydrolysis of starch present in cassava fibrous waste results in a formation of brownish yellow hydrolysate due to the use of higher acid concentration than that needed in case of pure starch. Thus, it dictates application of stronger downstream processing unit operations such as deproteinization, clarification and decolouration. Among the various deproteinizing agents evaluated, bentonite and kaolin were found to be the best and their use resulted in the removal of 20% protein and 60–70% red as well as yellow colours. Kaolin was selected based on economic considerations. The data indicated that 5% (w/v) kaolin, 10 min contact time at 25°C and a pH of 1.0–1.5 of the hydrolysate were suitable. For complete decolouration, 0.5% (w/v) activated carbon at 25°C with a contact time of 30 min was needed. Treatment with activated carbon also results in protein removal and is maximum at 40°C. These stronger down-stream processing unit operations lead to an acceptable product conforming to the standard.     

不同干燥方法对荷花花瓣抗氧化活性和化学成分的影响

研究不同干燥方法(阴干、晒干、鼓风干燥、微波干燥、冷冻干燥)对荷花花瓣抗氧化活性和总黄酮、总酚、花青素含量的影响。以抗坏血酸作为阳性对照,采用还原能力、DPPH自由基清除和羟基自由基清除3种体外抗氧化模型,评价了不同干燥方式处理的荷花花瓣的抗氧化能力,并对总黄酮、总酚和花青素的含量进行了测定。结果表明:荷花花瓣具有较强的还原能力、清除DPPH自由基和羟基自由基的能力;不同干燥方法对荷花花瓣的抗氧化活性和活性物质的含量均有较大的影响,其中冷冻干燥的荷花花瓣抗氧活性能力最强,且总黄酮、总酚和花青素的含量最高,分别为60.20、85.35 mg/g和150.3 ng/g;而晒干荷花花瓣的抗氧化能力最差,黄酮、总酚和花青素的含量最低,分别为0.39、19.08 mg/g和2.8 ng/g。     

Peanut Moisture/Size, Relation to Freeze Damage and Effect of Drying Temperature on Volatiles

Moisture level and seed size at time of exposure to freezing temperatures affected the chemical composition of peanuts. Potassium and total organic carbon in the leachate from freeze damaged peanuts decreased as moisture level of peanuts exposed to freezing temperatures was decreased from 40 to 6%. Acetaldehyde and ethanol, excellent indicators of cold stress, also decreased in concentration as moisture level of peanuts exposed to freezing was decreased from 40 to 6%. Small seeds were more severely damaged than larger seeds, and higher drying temperatures increased concentrations of acetaldehyde, ethanol, and ethyl acetate.