浓缩工艺和MPC质量浓度对其乳化特性的影响

研究了蒸发浓缩乳蛋白浓缩物(EP-MPC)和纳滤浓缩乳蛋白浓缩物(NF-MPC)的乳化性能,并比较了MPC的质量浓度对两种乳蛋白浓缩物乳化能力和乳化稳定性的影响。结果表明,两种MPC均可以在质量浓度为60g/L时形成良好乳浊液,此时它们的乳化能力没有显著性差别。但无论是刚形成的乳浊液还是贮藏一段时间后,NF-MPC稳定的乳浊液的稳定性明显高于EP-MPC。同时EP-MPC对浓度的变化较为敏感,低于或高于最适浓度都会导致乳化液滴粒径大幅度增加,且乳化液更加不稳定。     

复水条件对脱水香椿品质的影响

本文研究了不同复水条件处理后脱水香椿的香气成分、色泽、复水比、亚硝酸盐溶出率及维生素C保存率的变化。结果表明:复水温度40℃时,能较好地保护脱水香椿特征香气和萜烯类及含硫化合物等主要香气成分;随复水时间延长,脱水香椿L*降低,复水温度对其无显著影响;复水过程中a*先降低后升高,30 min时a*降至最低即颜色的绿值最大,b*亦较低,且复水温度40℃条件下a*和b*均最小;于复水温度40℃、料液比1:60(g/m L)条件下复水30-40 min,此时复水比及亚硝酸盐溶出率均较高;复水初期维生素C保存率大大降低,20 min后趋于平缓。适度降低复水温度和缩短复水时间有利于保护复水香椿的色泽、香气及营养素,并能保证其安全性。该研究为科学合理利用我国特色资源香椿提供技术依据。     

加工工艺和复水条件对脱水胡萝卜复水性的影响

研究不同切片厚度、干制温度及复水条件对胡萝卜片复水性的影响.在单因素试验基础上,采用二次回归正交旋转组合设计对胡萝卜片复水条件进行优化研究. 结果表明,胡萝卜片厚度小于4 mm,干燥温度65℃,胡萝卜片的复水性最好;复水过程中,各因素对胡萝卜片复水比的影响次序依次为:浸温>浸时>用水量.最佳复水条件为浸温77℃、浸时145min、用水量200mL/3 g干制品.     

复水温度对香菇复水特性及品质的影响

香菇是中国产量最高和市场消费量最大的食用菌。干制是香菇的主要加工方式,而干香菇需复水后才能作为原料被烹调或进一步加工。本研究将热风干燥的香菇分别在25,45,65℃和85℃下复水,研究香菇复水过程中复水比、外观、质构和风味品质的变化。结果表明,在45℃复水270 min,干香菇吸水后表面的褶皱较为舒展,微观结构显示其菌丝恢复膨胀且伸展。同时,其复水比稳定保持在3.88,剪切力(1 290.28 g)、弹力(0.66 g)和复原力(0.34 g)适中,咀嚼性(656.02 g)最大,说明香菇复水完全且质地柔软适中,易被切开。此外,45℃复水香菇所含特征含硫化合物的含量较高,以1,2,3,5,6-五硫杂环庚烷(67.02%)和1,2,4-三硫环戊烷(39.06%)为主,风味较浓郁。综上,复水温度显著影响香菇复水后的食用品质,将干香菇在45℃复水270 min可获得品质较好的复水香菇。     

不同复水条件对香菇特征香味物质的影响

目的研究干香菇经不同复水条件处理后其特征香味物质含量的变化,实现干香菇的科学复水。方法新鲜香菇经热风干燥后进行复水处理,通过顶空固相微萃取-气相色谱-质谱联用(headspacesolid-phase microextraction-gaschromatography-massspectrometry,SPME-GC-MS)的方法对复水香菇中的挥发性含硫化合物和八碳化合物进行分析,以环己酮为内标物,采用内标法进行定量分析,分别考察不同复水时间、不同复水温度和不同复水pH值下香菇中特征香味物质的含量。结果经不同复水时间处理后,香菇中含硫化合物含量为38.30～79.84μg/g,八碳化合物含量为4.33～10.97μg/g;经不同复水温度处理后,香菇中含硫化合物含量为12.82～44.45μg/g,八碳化合物含量为2.50～9.84μg/g;不同pH值条件下复水处理后,香菇中含硫化合物含量为6.10～72.52μg/g,八碳化合物含量为0.86～7.61μg/g。结论结果表明,干香菇在温度为40℃、pH值为9时,复水处理40min,其挥发性含硫化合物的含量较高,复水香菇表现为浓郁的"香菇味";干香菇在温度为40℃、pH值为7时,复水处理20 min,其挥发性八碳化合物的含量较高,复水香菇表现为明显的"蘑菇味",应根据实际情况选择合适的复水条件。     

葡萄酒活性干酵母复水活化条件的研究

用复水稀释倍数，复水活化温度和复水活化用水葡萄糖含量三因素三水平正交试验，对每克活性干酵母的活细胞数和活细胞率进行了比较和分析，得出较佳复水活化条件并进行了验证试验，结果复水倍数为1：10，复水活化温度为35度，复水活化用水葡萄糖含量为4％是最佳条件。     

葡萄酒活性干酵母复水活化条件的研究

研究了葡萄酒活性干酵母的较佳复水活化条件。采用复水稀释倍数、复水活化温度和复水活化用水葡萄糖含量三因素三水平的正交试验 ,对每克活性干酵母的活细胞数和活细胞率进行了比较和分析 ,得出较佳复水活化条件并进行了验证试验。得出了复水倍数为 1∶ 1 0 ,复水活化温度为 35℃ ,复水活化用水葡萄糖含量为 4%是最佳条件。     

葡萄酒活性干酵母复水活化条件的研究

研究了葡萄酒活性干酵母的较佳复水活化条件。采用复水稀释倍数、复水活化温度和复水活化用水葡萄糖含量三因素三水平的正交试验 ,对每克活性干酵母的活细胞数和活细胞率进行了比较和分析 ,得出较佳复水活化条件并进行了验证试验。得出了复水倍数为 1∶ 1 0 ,复水活化温度为 35℃ ,复水活化用水葡萄糖含量为 4%是最佳条件。      

人造米复水过程水分传递特性的研究

对人造米复水过程中水分传递特性进行了研究，结果表明：含水量和温度对扩散系数有显著影响；在复水过程中，扩散系数随含水量增加而增大；与温度呈指数上升趋势，一定温度下的活化能与含水量呈正相关。     

干燥脱水条件对片烟复水特性的影响

为研究不同热湿处理过程间的相互关系,利用调温调湿箱模拟片烟干燥和复水过程的工艺条件,考察了干燥介质温湿度及不同初始含水率对片烟复水特性的影响.结果表明:①二元Weibull分布模型可用于描述片烟干燥过程动力学,且模型参数α可作为表征干燥进程快慢的特征时间参量;②较低干燥温度(70,80℃)下,片烟复水速率随干燥介质湿度的增加呈明显减小趋势;较高干燥温度(90℃)下,干燥介质湿度对片烟复水速率影响则相对较小.复水平衡含水率随干燥介质湿度的增大而降低,不同温度干燥后的片烟复水平衡含水率差异不大;③相同干燥条件下,随片烟干燥后含水率的降低,其复水速率增加.片烟初始含水率从14％降至5％时,复水过程中的平衡含水率呈先增加后降低的趋势,初始含水率降至5％时,复水过程的平衡含水率减小更明显.     

Effect of dynamic process conditions on nitrogen oxides emission from a nitrifying culture

Nitric oxide (NO) and nitrous oxide (N2O) emissions from nitrifying ecosystems are a serious threat to the environment. The factors influencing the emission and the responsible microorganisms and pathways were studied using a laboratory-scale nitrifying reactor system. The nitrifying culture was established at growth rates relevant to wastewater treatment plants (WWTPs). During stable ammonia oxidation, 0.03% of ammonium was emitted as NO and 2.8% was emitted as N2O. Although mixed cultures were used, clear responses in emission of ammonia oxidizing bacteria (AOB) could be detected and it was concluded that the denitrification pathway of AOB was the main source of the emissions. Emissions of nitrogen oxides in the system were strongly influenced by oxygen, nitrite, and ammonium concentrations. Steady state emission levels greatly underestimate the total emission, because changes in oxygen, nitrite, and ammonium concentrations induced a dramatic rise in NO and N2O emission. The data presented can be used as an indication for NO and N2O emission by AOB in plug-flow activated sludge systems, which is highly relevant because of the atmospheric impact and potential health risk of these compounds.     

Effect of dairy powder rehydration state on gel formation during yogurt process

Protein fortification and solubilisation into the milk base are important parameters enhancing yogurt texture. In this study, the milk base prepared from reconstituted skim milk powder was fortified with 2% of 'aged' (1 year old) or 'fresh' micellar casein (MC) powder. Micellar casein powders were left to rehydrate at 20°C for different times (5 or 180, 300, 480, 900 or 1440 min) before acidification with glucono-delta-lactone. The rehydration of the MC powders into milk was monitored with a granulo-morphometer equipment, thus, for the first time, allowing the elucidation of MC rehydration process into an opaque environment such as milk. Whereas the gel point was delayed proportionally to the powder rehydration length, the storage modulus appears unaffected. Besides, the gelation onset was not altered by the powder age.     

Effect of puffing conditions on physical properties and rehydration characteristic of instant rice product

The aim of this work was to study the effects of puffing conditions on the properties of instant rice and to obtain optimal processing condition for product with rehydration time within 5 min. Thai jasmine rice was soaked, cooked and dried at 80 °C in a tray dryer before being puffed at different moisture contents (15–20% wb), temperatures (200–220 °C) and time intervals (20–30 s). The rice puffed at higher moisture contents and puffing temperatures for longer time exhibited higher volume expansion ratios and shorter rehydration times. Presumably, case hardening of the grain surface occurred. Instant rice that can be rehydrated in 5 min with more acceptable hardness than the commercial instant rice was obtained. Regression models to predict the quality of instant rice were developed using response surface methodology.     

挤压工艺对糙米速食粥复水效率的影响及工艺优化

为满足人们对糙米食品的需求,改善糙米的粗糙口感并保持其良好的营养品质,以黑龙江圆粒粳糙米和江西早籼糙米的复合粉为原料,通过挤压膨化技术对糙米复合粉进行加工,采用单因素实验探讨加工工艺参数对糙米挤压速食粥复水率、复水时间与米汤固形物含量之间的关系,经过响应面分析得到最佳加工工艺。结果表明:最佳工艺条件为挤压温度100℃、水分含量29.22%、螺杆转速185r/min。该工艺制得的糙米挤压速食粥复水率为2.359%,复水时间为10.67min,均与预期值无显著性差异,该工艺稳定可行。本研究为糙米挤压速食粥的制作提供技术指导,并为糙米的开发与利用提供理论基础。     

Modelling of the rehydration process of brocolli florets

The aim was to study the rehydration kinetics of branched bodies such as broccoli florets, at different temperatures, and to this end a diffusional model was used considering the product structure as a sum of different sized cylinders. The rehydration rate was observed to increase with water temperature. The equilibrium moisture content of the product linearly decreased as the water temperature increased (r=0.95). A close fit between the model and the experimental data was obtained when the effective diffusion coefficient (D_eff) and equilibrium moisture content (W_e) were identified at each temperature (average explained %var=99.65). The temperature influence on D_eff was interpreted by the Arrhenius relationship, with an activation energy of 89.73 kJ/mol.     

工艺条件对奶冻品质影响的研究

为阐明工艺条件对奶冻品质的影响,选取水化、均质和杀菌方式3个关键工艺点为研究对象,以产品的硬度、弹性和d_4,3值为指标,采用L₉（3⁴）正交实验对水化温度、水化时间及均质压力进行优化,同时研究了杀菌温度和杀菌时间对奶冻质构特性、粒径分布和感官品质的影响。结果表明,在75℃水化15min,采用30MPa均质使奶冻获得较优的硬度、弹性和d_4,3值;100℃/30min杀菌处理得到的产品粒径较小,呈现乳白色有光泽且硬度、弹性、胶着性和咀嚼性能等质构指标都优于137℃/5s和121℃/15min的感官品质。此工艺操作简单、稳定性好、可行性高。      

Effect of porosity on rehydration of dry food particulates

Rehydration of food particulates is a complex phenomenon affected by numerous factors that typically include pre‐drying treatments, mode of dehydration, structure, composition and medium viscosity. Freeze drying (FD), air drying (AD) and their combinations, were utilized to produce an array of porosities, ranging from very high to very low values for FD and AD carrots, respectively. Bulk porosity correlated significantly with open, but not with closed, porosity. Bulk and open porosities decreased with AD time. Scanning electron micrographs of the FD samples verified their organized and more open structure in comparison with the AD carrots. Rehydration ratio increased with bulk and open porosity, and was not affected by the closed porosity. The effective moisture diffusivity, derived from fitting the normalized Weibull distribution, increased with bulk and open porosity and was about two orders of magnitude higher for the FD, than for the AD, carrots. The Weibull shape parameter, β, was inversely related to porosity. Its values indicated that water uptake of only the AD carrots followed a Fickian diffusion. A critical porosity value above which water mechanism changed from a Fickian diffusion to imbibition into a porous medium is suggested. Copyright © 2004 Society of Chemical Industry     

干燥方式对速煮绿豆复水性影响的研究

研究了热风干燥、微波干燥、热风和微波结合干燥3种干燥方式对速煮绿豆复水性的影响,探讨了3种干燥方式的最佳干燥条件,并获得最佳干燥方式。实验结果表明,热风和微波结合干燥方式复水效果最佳,其最佳干燥条件为:先100℃热风干燥30～40min后,放置在密封容器36h,再用462 W微波干燥4～6min后的速煮绿豆,形态保持完整,内部组织结构疏松、多孔,有膨化效果,易于水分的进入,复水时间为9min,复水率达到5.0。     

玉米馒头制备工艺条件对其感官品质的影响

采用响应面分析法(RSM)研究了膨化玉米粉、发酵玉米粉、加水量及醒发时间对玉米馒头感官品质的影响,并将玉米馒头与小麦馒头的质地特性进行比较。结果表明,膨化玉米粉25%、发酵玉米粉45%、小麦粉30%、加水量60%、醒发时间50 min时,感官评分为89.16,制得的玉米馒头与小麦馒头质地特性无显著差异(p>0.05),且颜色金黄、软韧适中、组织均匀、玉米香味浓郁,感官品质最佳。以玉米预混粉为原料制备玉米馒头,不仅可以拓宽我国玉米深加工应用领域,也大大提高了玉米的利用价值。      

不同工艺条件对西式重组灌肠质构特性的影响

以猪肉和鸭肉为原料制作西式重组灌肠,研究原料肉混合比、斩拌时间、食品胶添加方式、蒸煮时间对其质构(硬度、弹性)的影响,并对不同工艺条件对质构的影响机理进行了分析。结果表明:当原料肉混合比(鸭肉:猪肉)=2:8,斩拌时间6min,采用冷水分散的添加方式,蒸煮时间25min时,西式重组灌肠的质构特性最佳。