液氮喷雾式食品流态化速冻装置的研制

该文介绍了一种新型的液氮喷雾式食品流态化速冻装置,该系统以液氮为冷源,取代了传统庞大的制冷装置,并将液氮喷淋预冻和流态化速冻两种方法有机结合,实现了食品的快速冻结,提高了冻品品质     

液氮喷雾流态化速冻机的研制

介绍了一种结合液氮喷淋和流态化速冻各自特点的液氮喷雾流态化速冻机，它以液氮为冷源，替代庞大复杂的制冷系统，实现了单体快速冻结，减少了初投资，提高了食品冻结质量。     

流态化速冻装置布风板实验研究

针对目前流态化速冻装置在速冻过程中速度分布和压力分布不均匀导致食品流化状态与冻结效果不佳等缺点,课题组从布风板孔隙形状(正方形、三角形和圆形)、孔隙率和孔隙分布3个角度出发,设计出16种布风板,以提高装置对不同种类食品的适应性要求,提高装置能效比从而达到节能的目的。文中研究设计的布风板可改善流态化速冻装置在冻结过程中的流化程度与冻结效果,同时不同孔隙形状的设计也满足食品颗粒形状的多样性需求。     

蓝莓不同冻结方式下工艺特性及贮藏品质的研究

研究了在液氮式流态化速冻和-25℃冰箱慢速冻结两种冻结方式下蓝莓的冻结、解冻工艺特性及其冻后样品在贮藏期间的感官品质变化规律。结果表明:就冻结方式而言,蓝莓液氮式流态化速冻优于冰箱慢冻;就解冻工艺而言,解冻规律呈现多样性。质构仪对蓝莓硬度的检测与图像处理法对蓝莓内部颜色的检测,结果均反映出同阶段流态化速冻样品优于冰箱慢冻样品。通过对蓝莓腐烂率的统计,确定了液氮式流化床速冻蓝莓的贮藏期150天左右,优于冰箱慢速的105天贮藏期。     

液氮速冻技术在食品中的应用

随着社会的发展和人民生活水平的提高,人们对速冻食品的需求和品质也会相应提高,速冻技术也需要提高。液氮速冻技术是一种新型速冻技术,具有冻结速率快、速冻食品的品质高等优点。文章综述了液氮速冻技术、国内外液氮速冻设备的研究进展及其在肉制品、水产品、果蔬类、预制食品领域的应用,分析了液氮速冻技术及设备存在的问题,并对多种速冻食品速冻方式的组合模式进行了分析。     

液氮速冻技术在食品中应用的研究进展

液氮速冻技术是一种食品冷加工技术,在食品加工等领域有广泛的应用。阐述了液氮速冻技术的基本原理及其在食品中应用的国内外现状,并对液氮速冻技术在食品冷加工领域中应用的前景作了展望。     

蓝莓液氮式流态化速冻工艺研究

利用液氮式流态化速冻的方式对蓝莓进行加工,通过设置不同的冻结温度、风机风速和床层高度等工艺参数,采用混合均匀实验设计,检测不同实验条件下蓝莓的VC、花青素、失水、可溶性固形物、DPPH自由基清除率和还原力六项指标。多元线性回归分析显示了液氮式流态化速冻蓝莓适宜的工艺条件为:冻结温度为-40℃,风机风速4.5m/s,床层高度3.6cm。通过对回归方程降维,分析了流态化工艺参数对蓝莓六项指标的影响规律,为进一步优化蓝莓的流态化速冻工艺提供了理论基础。     

日本的液氮速冻与制冷设备

1 液氮快速速冻装置液氮快速速冻装置由隔热隧道、喷淋装置,纵贯于隧道的网格传送带、减速器,无级变速器、搅拌风机、离心排风机、电磁阀、电器控制箱等部件组成.液氮自贮罐按预定温度自动输送至喷咀,在隧道内稳定喷淋,与置于传送带上的被速冻食品热交换,连续进行速冻.     

食品流态化速冻技术研究进展

随着现阶段冷链产业的逐渐完善,作为最具潜力的速冻技术之一的流态化冷冻也越来越受到人们的重视。流态化冷冻易于实现单体速冻和连续化生产,冻品营养成分保存好的优势十分明显,而不足之处在于能耗大、运行成本高。笔者着重介绍了流态化冷冻发展过程中技术上的若干改进方案,包括预冷技术、节能技术以及冷冻过程的仿真手段。预冷技术和节能技术的更新升级将会在提升食品冻藏品质的同时减少能耗。由于流态化速冻过程受到的影响因素较多,仿真手段的应用可以更加省时省力地得到不同食品颗粒最佳的冷冻工艺参数。     

液氮在食品速冻中的应用

用液氮速冻食品,一般可分为液氮浸渍冻结,液氮蒸气吹风冻结和液氮喷淋冻结3种方法。液氮浸渍冻结是使食品体跟液态氮浸渍接触,液氮吸收食品的显热和潜热而被蒸发,借以达到食品速冻的目的。液氮蒸气吹风冻结则是让液氮在特殊的蒸发器中蒸发,然后以很高的流速强制吹送至食品表面,从而使食品快速冻结。液     

Production Rate Optimization in Continuous Fluidized Bed Freezers

A model for predicting freezing times of individual particles is adapted to operating conditions of fluidized beds. The equation is linked to a model for movement of solids along the continuous fluidized bed which includes longitudinal mixing. The equations obtained allow the design and optimization of fluidized bed freezers. Calculations are performed for beds of green peas. Maximum values in the production rate are found in terms of bed dimensions and operating conditions. A nomogram is provided to facilitate equipment design under conditions of maximum production rate and minimum blower power consumption.     

GAS PARTICLE HEAT TRANSFER COEFFICIENT IN FLUIDIZED PEA BEDS

Individually Quick Frozen food production has led to the development of fluidized bed freezing equipment, where the previously cooled fluidizing air freezes the food by direct heat transfer. The operating conditions of these beds, as well as their design characteristics, are consequently related to the gas-particle heat exchange including the fluid dynamic complexity of aggregative fluidization. The purpose of this paper is the experimental determination of gasparticle heat transfer coefficients for fluidized pea beds and their extension to conditions prevailing in industrial processing. Heat transfer coefficients were determined for both, peas and porous alumina pellets, in a system where particles were dryed by the fluidizing air. Transfer coefficients were evaluated for various gas velocities and bed depths. The results obtained for alumina pellets and those for peas can be satisfactorily correlated by using the Archimides number, and show good agreement with correlations obtained by other authors.     

汽-液-固三相流化床蒸发器浓缩食品液体的实验研究

介绍了三相流化床蒸发器的结构特点，对其传热和防、除垢性能进行了研究；论述了把汽-液-固三相流化床蒸发器应用于食品液体浓缩的可行性。研究结果表明：汽-液-固三相流化床蒸发器具有良好的传热和防、除垢性能，在食品工业中具有一定的应用前景。     

热泵式流化床干燥装置及其应用优势

热泵式流化床干燥装置干燥食品的突出优点是节能和食品干燥质量好。本文对热泵式流化床干燥食品的特点进行了简要介绍，对热泵式流化床的结构性能进行了较深入的分析。对这种新型装备的推广与普及所需解决的问题及其技术思路进行了探讨，并对热泵式流化床食品干燥成套装备的市场应用前景进行了预测。     

A model for heat transfer in cryogenic food freezing

An experimental study of the heat transfer between liquid nitrogen sprays and a model food (a gelatine slab) was carried out under conditions similar to those in a cryogenic freezer. Measurements of heat flux and local mass flow rates of the spray were made at various liquid N₂ pressures and various temperature differences between the spray and the food surface.
At higher spray pressures, the heat transfer coefficient increases with the mass flux density of the liquid available at the food surface. The quantity of liquid nitrogen sprayed onto the solid surface, the mean droplet size, spray velocity, surface coverage and the mean temperature difference between the boiling nitrogen and the food surface are major factors influencing the rate of heat transfer during the freezing process. Although the heat transfer coefficients at the food surface are much less than those obtained for individual droplets, the model provides useful data.
The results are critically discussed in relation to cryogenic freezing of foods.     

深冷冻技术在益生菌生产中的应用

深冷冻主要是利用低温制冷剂(液氮、液态、CO2等)为冷却介质,通过热量的对流和传导使冻品快速冻结达到低温处理的目的。冻品以足够快的冷却速度实现玻璃态,从而降低菌体细胞损伤。在益生菌生产中,深度冷冻效果好、菌体失活少、生产效率高、设备投资维护费用低,优于传统的冷冻干燥。益生菌生产中主要利用颗粒滴冻式设备,比传统冷冻装置有更多优点。深冷冻过程中主要存在胞外冻结和胞内冻结伤害两方面,但结合使用合理的保护剂可以降低细胞伤害,保护剂分为渗透性和非渗透性两大类。     

液氮间歇式浸渍冻结对饺子冻裂率及感官品质特性的影响

为探究液氮间歇式浸渍冻结对饺子色差、质构、感官品质和微观结构的影响,本文以冻裂率为指标分别研究液氮浸入时间、间隔时间、浸入次数对饺子的影响;以低温冰箱冻结、螺旋隧道式冻结为对比,采用色差仪、质构仪、扫描电镜等分别研究液氮间歇式浸渍冻结对饺子色泽、质构、感官特性及微观结构等品质特性的影响.结果表明,当液氮单次浸入时间为2...     

Dry-pasteurization of egg albumen powder in a fluidized bed. II. Effect on functional properties: gelation and foaming

Dry‐pasteurization of egg albumen (EA) powder in a fluidized bed was studied in two experiments. Experiment 1 consisted of two different temperatures (90 and 130 °C) and experiment 2 of two air moisture levels (high and low). Powders were processed from 10 min to 3 h. The reference treatment was traditional pasteurization at 90 °C for 21 h. The fluidized bed treatment effects on gel texture, water‐holding capacity (WHC), protein binding, gel colour, foaming capacity, foam stability and surface pressure were evaluated. Gels of EA powders treated at high temperature and high air moisture levels exhibited higher stress, strain and WHC values than gels of untreated EA powder. The gel colour became significantly darker, greener and less yellow by fluidized bed treatment. Foaming and surface activity properties were un‐affected by the treatments, however, foam stability against liquid drainage correlated positively with surface pressure.     

Modeling of Residence Times in Continuous Fluidized Bed Freezers

A longitudinal dispersion model is proposed for analyzing the movement of peas along continuous fluidized bed freezers. By comparing the model with experimental data, a dispersion coefficient is obtained which correlates satisfactorily with the bed height and the superficial air velocity. Thus, minimum residence times can be predicted in terms of bed dimensions and operating conditions in the fluidized freezer. By adapting an individual particle model for freezing time prediction to the existing conditions in fluidized bed freezers, the analysis of production rate in terms of design parameters is performed. Thus, an optimum bed height which maximizes the production rate per unit of grid area is obtained.     

高温高压循环流化床锅炉在高原地区的应用

文章通过对YG-240/9.8-M13高温高压循环流化床锅炉的工艺设备进行计算,与传统沿海内地大型纯碱厂使用的锅炉进行技术对比的基础上,论证了在高原地区新建大型纯碱装置的热电锅炉工艺设备选型上,技术创新的选择YG-240/9.8-M13高温高压循环流化床锅炉达到了设计要求,满足了创新后的设计生产能力。