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.     

不同干燥方式对铁棍山药品质的影响

以外观、营养成分、复水性及超微结构为指标,比较4种不同的干燥方式对铁棍山药品质的影响。冻干(FD)对铁棍山药品质的保留最好,冻干真空微波联合干燥(FD-MVD)对产品品质的保留接近于FD,且能够使干燥时间缩短31%。微波真空干燥时间最短,但品质不如前两种干燥方式。热风干燥(AD)对感官品质和维生素C破坏较多,但对于多糖含量的保持与其它方法无异。超微结构的结果表明,MVD和AD对结构破坏较多,而FD和FD-MVD很好的保持了原有的细胞结构。     

Stability of quercetin derivatives in vacuum impregnated apple slices after drying (microwave vacuum drying,air drying,freeze drying) and storage

Microwave vacuum drying (MVD) was investigated for apple slices enriched with quercetin derivatives by vacuum impregnation (VI). Additional freeze drying (FD) and air drying (AD) were conducted. Compared to native apples, the impregnated tissue resulted in higher moisture content, elevation of weight and significant browning, due to the incorporated VI solution. The total quercetin content and quercetin glycoside composition were not affected by MVD and FD. The vacuum conditions protect the polyphenols from oxygen dependent degradation and browning reactions. AD resulted in an average quercetin glycoside loss of 44% and undesirable changes, particularly discoloration. The degradation is caused by both non-enzymatic and enzymatic reactions. The pulsed microwave energy intake improved the drying result in structure and led to a faster drying process of 130 min. The bulk density of MVD apple chips (0.69 g/ml) ranged between 0.33 g/ml for FD and 0.75 g/ml for AD. The final moisture content was the lowest after FD (6.8 g/100 g), followed by 9.0 g/100 g after MVD and 12.7 g/100 g after AD. The shelf life was significantly influenced by storage temperature and time. After 12 month at 20 °C, the total quercetin content decreased by 21%.     

Microwave freeze drying of sea cucumber (Stichopus japonicus)

Freeze drying (FD) yields the best quality of dried sea cucumber but at the cost of long drying time and also the overall cost. Air drying (AD) gives an unacceptably poor quality product. To achieve faster drying along with a high quality product a microwave freeze drying (MFD) technique was developed to dry sea cucumbers. The relationship between corona discharge and microwave power at various pressures and initial moisture content conditions was studied to avoid the possibility of corona discharge during MFD. According to the drying characteristics of MFD, a control strategy for the MFD process was also developed. MFD reduced the drying time by about half of conventional FD process and provided a similar good product quality.     

基于iTRAQ技术的鸡蛋清三种干燥方式差异蛋白质组分析

为探究真空冷冻干燥(vacuum freeze-drying, FD)、喷雾干燥(spray-drying, SD)和微波真空冷冻干燥(microwave vacuum freeze-drying, MFD)3种干燥方式对蛋清蛋白的差异,利用iTRAQ技术对三者进行蛋白质组差异分析,在得到的157种具有定量信息的蛋清蛋白中,鉴定出87种差异蛋白。MFD vs FD组上调蛋白质数量为46个,占差异蛋白质总数的67.6%。KEGG富集显示,MFD vs FD组和MFD vs SD共有2个基因通路显著富集,分别为折叠和降解、运输和分解代谢。此外,在差异蛋白中筛选出4种蛋白质在干燥过程中丰度变化显著,分别为黏蛋白、血清白蛋白、卵清蛋白相关蛋白Y亚型X1和卵白蛋白相关蛋白Y。该研究首次采用蛋白质组学的方法分析不同干燥方式处理后的鸡蛋清差异蛋白的表达变化,为今后生产和开发高品质蛋清粉及功能性蛋制品提供参考依据。     

不同干燥方式对面片微观结构及品质的比较

本文研究了面片的热风干燥(Hotairdrying,HAD)、真空冷冻干燥(freeze-drying,FD)、微波干燥(microwavedry,MD)、微波真空干燥(Microwave vacuum drying,MVD)和热风-微波联合干燥(hot air followed by microwave drying,HAD+MD)五种不同干燥方法及其对面片物理特性和微观结构的影响。通过以上研究表明:不同干燥速率为MVD>MD>HAD+MD>HAD>FD;面片复水率为FD>MVD>MD>HAD+MD>HAD;面片总色差值FD面片和MVD面片最低并无差异性显著(p>0.05),HAD总色差值最高,为19.56,面片色泽较差。HAD+MD和MD面片总色差值无差异性显著(p>0.05)。面片复水4 min后质构测定发现MD、MVD组延展性最好,分别为81.58 g/sec、72.58 g/sec,FD组剪切力各指标都表现较差,HAD组硬度和咀嚼性较大,分别为1652.88 g、5294.77g.sec。面片扫描电镜观察中,FD面片和MVD面片均观察到均匀密集的孔隙结构,MD面片和HAD+MD面片有明显不均匀孔隙结构,而HAD面片几乎观察不到孔隙结构。各干燥方式对面片的感官评价中FD面片总体评价最佳,MVD、MD面片其次,HAD+MD,HAD面片感官评分最差。综合看来,MVD干燥可以作为开发新疆汤饭产品中面片的适合脱水方式。     

Comparison of Freeze-Drying with Three Different Combinations of Drying Methods and Their Influence on Colour,Texture, Microstructure and Nutrient Retention of Button Mushroom (Agaricus bisporus) Slices

Freeze-drying (FD) and three different combinations of drying methods: freeze-drying combined with hot air drying (FD?+?AD), freeze-drying combined with vacuum drying (FD?+?VD) and freeze-drying combined with microwave vacuum drying (FD?+?MVD) were used to dry button mushroom slices. A comprehensive analysis of dried products was performed on their colour, texture, nutrient retention, microstructure and energy consumption. The results showed that, under conditions of 38 % moisture content changing point, most of the parameters including L* values, a* values, average density and hardness of FD?+?VD and FD?+?MVD samples had no remarkable changes (p?>?0.05) compared with FD samples. However, only FD?+?MVD method can reduce drying time by 35.63 % in comparison of FD method, although all the combination drying methods can reduce the energy consumption. Moreover, FD?+?VD and FD?+?MVD products were better than FD?+?AD products in nutrient retention except that content of vitamin C was comparatively lower during FD?+?MVD process. In conclusion, the FD?+?MVD method has advantages in terms of efficiency and energy saving and could be preferred to produce high-quality products.     

干制方式对鲜食枣脆片香气品质的影响

通过对微波真空冷冻干燥(microwave vacuum freeze drying,MVFD)、微波真空膨化(microwave vacuum puffing,MVP)、真空冷冻干燥(vacuum freeze drying,VFD)和中短波红外干燥(short-and medium-wave infrared drying,ID)4种鲜食枣脆片的香气成分的分析,明确干制方式对鲜食枣脆片香气品质的影响。结果表明:通过固相微萃取结合气相色谱-质谱联用技术,从4种干制鲜食枣脆片中鉴定出70种香味物质,包括醇类、酸类、醛类、酯类、酮类、烃类和其他类化合物共7类成分,其中酸类物质29种,是VFD、MVFD和MVP枣脆片中主要的香气成分,醛类物质31种,是ID枣脆片中主要的香味物质,不同干制方式制得的枣脆片香气品质差异很大。对7类香气成分进行主成分分析,并建立香气品质评价模型,得出MVP鲜食枣脆片的综合得分最高,其香气品质最佳,其次是VFD、MVFD,均优于ID,为鲜食枣的干制加工提供了技术依据。主成分分析可以作为鲜食枣脆片香气品质的评价方法。     

真空微波干燥重组鱼丸的研究

以鱼肉为主要原料,采用真空微波膨化技术制作松脆脱水重组鱼丸.通过大量单因素实验,研究了各种辅料和蒸煮时间对重组鱼丸膨化率和感官品质的影响;进一步采用真空微波膨化技术,研究了微波功率、真空度对重组鱼丸干燥速率、膨化率和感官品质的影响.结果表明,重组鱼丸的适宜配方和工艺条件为:鱼肉(经过预处理)100 g,糯米粉10 g,猪肥膘4 g,食盐2 g,白砂糖6 g,葱姜蒜粉0.6g;蒸煮时间为6 min,真空微波炉的真空度和微波功率分别为-0.095MPa和180W,干燥时间为15 min,得到的成品表面呈现均匀的淡黄色,有鲜美的鱼肉味,口感细腻、松脆.     

Comparison of Freeze-Drying and Freeze-Drying Combined with Microwave Vacuum Drying Methods on Drying Kinetics and Rehydration Characteristics of Button Mushroom (Agaricus bisporus) Slices

Button mushroom slices were dried using freeze-drying (FD) and freeze-drying combined with microwave vacuum drying (FD?+?MVD) methods. Drying parameters including drying temperatures (20, 30, and 40 °C), chamber pressures (70, 100, and 130 Pa) and material layer thicknesses (single, double, and triple) during FD process, and microwave power densities (20, 40, and 60 W/g) and material layer thicknesses (single, double and triple) during MVD period of FD?+?MVD process, were investigated for their drying characteristics. The FD and FD?+?MVD products were then rehydrated at two temperatures (20 and 70 °C). Different mathematical models were tested with the drying and rehydration behaviors of button mushroom slices, and the effective diffusivities (D _eff) in the FD and FD?+?MVD processes were also calculated. The results indicated that based on the statistical tests, the Page model and logarithmic model provided the best fit for FD (in both FD and FD?+?MVD processes) and MVD (in FD?+?MVD process) curves, respectively. The regression equations obtained from selected models can accurately predict the relationships between moisture ratio (MR) and time (t). Furthermore, the D _eff values of the MVD period in FD?+?MVD process (2.318–5.565?×?10^?5 m²/s) were about ten times greater than those in FD process (1.291–3.389?×?10^?6 m²/s). In addition, the Peleg model gave a better fit for rehydration conditions applied in both FD and FD?+?MVD products. The values of equilibrium moisture content (W _e) of FD?+?MVD products were almost similar to those of FD products, which indicated that the rehydration capacities of the two dehydrated products were comparable.     

基于主成分分析法综合评价四种干燥方式对芜菁脆片香气品质的影响

通过测定真空冷冻干燥(freeze drying,FD)、变温压差膨化干燥(explosion puffing drying,EPD)、红外干燥(infrared drying,ID)、热风干燥(hot air drying,AD)四种不同干燥方式的芜菁脆片的香气成分,来研究不同干燥方式对芜菁脆片的香气品质的影响。使用顶空固相微萃取-气相色谱质谱联用法(HS-SPME-GC-MS)进行芜菁脆片香气成分的测定。并进行主成分分析(PCA),建立香气品质评价模型,计算不同干燥方式所得芜菁脆片的风味品质综合得分。结果表明:FD芜菁脆片的综合得分最高,其香气品质是最佳的,其次是AD与EPD,ID则品质最差。各类香气成分在4种芜菁脆片中拥有着不同的含量,这导致了4种脆片香气品质的显著差异,而且芜菁脆片的香气品质与干燥方式、干燥温度和干燥时间等众多因素有关。因此利用主成分分析,可以实现对芜菁脆片品质的区分,为进一步研究干燥方式对芜菁脆片的品质影响提供理论基础,也为芜菁脆片的干制加工提供了技术依据。     

基于灰色关联分析法研究不同干燥方式对芜菁脆片的影响

通过比较真空冷冻干燥（freeze drying,FD）、变温压差膨化干燥（explosion puffing drying,EPD）、红外干燥（infrared drying,ID）、热风干燥（hot air drying,AD）4 种不同干燥方式对芜菁脆片物理性质、营养成分、微观结构等的影响,寻找最优的芜菁脆片干燥方式。使用理化分析技术测定芜菁脆片营养成分含量;色差仪、质构仪等测定物理特性;扫描电子显微镜观察微观结构;评分法进行感官评价;灰色关联分析与变异系数分析结合进行综合评价。结果表明：4 种不同干燥方式处理后的芜菁脆片的物理特性和营养成分含量均有显著变化,FD和EPD对营养成分的保留更为完整。扫描电子显微镜观察结果显示FD可使芜菁脆片形成疏松多孔蜂窝状结构,EPD可使芜菁脆片产生轻微蜂窝状效果,同时使结构更为紧密,使口感酥脆。干燥方式综合评价结果为：FD＞EPD＞ID＞AD。但FD设备及加工过程花费较高,生产周期较长。综合考虑脆片的物理特性、营养成分、微观结构、感官评价以及生产周期,可得出EPD为芜菁脆片的最适加工方式。     

Volatile components of white Hypsizygus marmoreus detected by electronic nose and HS-SPME-GC-MS: Influence of four drying methods

Four drying methods, viz hot air drying (HD), vacuum drying (VD), microwave-vacuum drying (MVD), and vacuum freeze-drying (FD), were used to dry white Hypsizygus marmoreus (WHM). The volatile and taste components of the dried WHM were comparatively analysed by electronic nose technology (E-nose) and head-space solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GS-MS). Principal component analysis (PCA) showed that E-nose could distinguish fresh WHM and four dried products clearly. Dominant volatile components in fresh WHM were found to be 1-octen-3-ol, 3-octanone, and (E)-2-nonenal. However, it was found that the drying methods caused damage to the 8-carbon compounds (C8), especially to 8-carbon alcohol greatly. For instance, HD produced more ester materials, MVD yielded more aldehyde compounds, FD brought more hydrocarbon products, and VD produced more ketone substances.     

载能微波在不同负压水平的干燥模式与应用

为回顾近年来载能微波在农产品干燥中的研究进展,并解析负压环境对干燥行为的影响,文章以微波干燥的负压水平和干燥模式为主线,阐述高水分农产品物料在低真空度的负压微波脉冲喷动干燥(pulse-spouted microwave vacuum drying,PS-MVD),中真空度的微波真空干燥(microwave vacuum drying,MVD),高真空度的微波真空冷冻干燥(microwave vacuum freeze drying,MVFD)的干燥模式及物料特性,同时对农产品物料“热风-微波真空”组合干燥、“微波真空-真空含浸”加工、“脉冲喷动微波真空冷冻干燥”工艺的创新应用展开讨论。     

Effect of blanching on microwave freeze drying of stem lettuce cubes in a circular conduit drying chamber

Effects of boiling water and microwave blanching methods on the dielectric properties, electrical conductivity as well as microstructure of stem lettuce cubes (as a model for plant tissue) were studied. The study also focused on how different blanching methods affect microwave freeze-drying (MFD) in a circular conduit drying chamber and conventional freeze drying (FD) of stem lettuce cubes. Results showed that the electrical conductivity of samples blanched by microwave was two times higher than that of boiling water blanched ones and five times higher than that of unblanched samples. Apart from that, dielectric constant (ε′) and loss factor (ε″) of the stem lettuce cubes decreased significantly after freezing. MFD duration of microwave blanched samples was approximately 4.5 h, reduced by 30% compared to boiling water blanched ones. MFD process in a circular conduit yielded products of high quality compared to that in a tray.     

A multi-stage combined heat pump and microwave vacuum drying of green peas

The effect of multi-stage heat pump fluidized bed atmospheric freeze drying (HP FB AFD) and microwave vacuum drying (MVD) on the drying kinetics, moisture diffusivities, microstructure and physical parameters of green peas was evaluated. The results were compared with those obtained for microwave vacuum drying (MVD) and hot air convective drying (HACD). In case of combined method, the initial drying rate was about 0.04 l/min. The application of MVD increased the drying rate to the values 0.08 l/min. The drying rates of green peas dried by MVD and HACD were 0.59 and 0.20 l/min, respectively. MVD samples were characterized by a structure with minimal changes in respect to fresh samples. However, HP FB AFD and MVD satisfied important requirements, such as high product quality (due to low material temperature during AFD and low pressure during MVD), and increased drying rates in the final stage due to application of microwave heating.     

基于主成分分析法综合评价4 种干燥方式对山药脆片香气品质的影响

为研究干燥方式对山药脆片香气成分和含量的影响,采用顶空固相微萃取结合气相色谱-质谱联用技术,分别对4?种不同干燥方式处理的山药脆片的香气成分进行测定与分析。从4?种干燥方法所得山药脆片样品共检测出33?种香气成分。其中冷冻干燥、膨化干燥、真空干燥、热风干燥所得山药脆片分别检测出13、15、11?种和14?种香气成分。主要分为醛类、腈类、酮类、烃类、醇类、酸类、酯类、其他类,对8?类香气成分进行主成分分析,建立香气品质评价模型,并通过主成分载荷图以及主成分得分图,得出冷冻干燥山药脆片的综合得分最高,其香气品质最佳,其次是膨化干燥、真空干燥均优于热风干燥。     

不同干燥处理对黑木耳粉理化特性和微观结构的影响

为了探讨不同干燥处理对黑木耳粉理化特性的影响,采用热风（hot air drying,HAD）、热泵（heat pump drying,HPD）、真空微波（microwave vacuum drying,MVD）和真空冷冻（vacuum freeze drying,VFD）4 种不同干燥方式对黑木耳进行干燥,并探讨了超微粉碎后黑木耳粉的理化特性,结果表明：不同方式处理的黑木耳粉的理化特性差异明显。VFD黑木耳粉的平均粒径最小,堆积密度最大,亮度最高,持水能力和流动性最好,水溶性指数和多糖溶出量最高,VFD黑木耳粉的品质优于其他干燥处理,但是VFD干燥处理能耗较高,MVD黑木耳粉的品质优于HPD和HAD处理,可作为黑木耳粉碎前干燥处理的备选方法。     

Quality Changes of Dehydrated Restructured Fish Product from Silver Carp (Hypophthalmichthys molitrix) as Affected by Drying Methods

Restructured fish slices from silver carp (Hypophthalmichthys molitrix) were dried using air drying (AD), freeze drying (FD), and vacuum drying (VD) (4 mm thickness) and microwave-vacuum drying (MVD) (2, 4, 6, and 8 mm thickness). Quality attributes of the dried products were compared in terms of their rehydrated characteristics, change in dimensions, color, texture, sensory values before and after rehydration, and change in volatile compounds. AD, FD, and VD resulted in the different levels of shrinkage while MVD caused some expansion in diameter and thickness in the 4-, 6-, and 8-mm-thickness samples. Rehydration caused significant swelling in AD, FD, and VD products (p?<?0.05) but insignificant change in MVD products (p?>?0.05). Drying methods significantly affected the color and texture of both dried and rehydrated products (p?<?0.05), but slice thickness had no significant effect on the color in MVD products (p?>?0.05). MVD products rehydrated faster and had higher rehydration ratio as well as lower water hold capacity, hardness, springiness, cohesiveness, and chewiness than others. In sensory evaluation, MVD products alone exhibited acceptable crispness and favorable odor. The rehydrated dried products were acceptable by the sensory panelists and were preferred in the order: FD, VD, AD, MVD. Gas chromatography-mass spectrometry revealed that drying significantly decreased the n-alkanals and 1-octen-3-ol content (p?<?0.05) and produced new aldehydes including 2-methyl-propanal, 3-methyl-butanal, and furfural in MVD products. This study demonstrated that drying restructured fish meat can be potentially used to develop the new dried fish products using optimal drying conditions.     

Analysis of Temperature Distribution and SEM Images of Microwave Freeze Drying Banana Chips

Compared with freeze drying (FD), microwave freeze drying (MFD) using microwave as the heating source can accelerate the drying rate of bananas. This paper presents the results of an experimental study of temperature distribution during the process of MFD banana chips. The results show that the temperature distribution is uniform during the sublimation drying stage, but not at the start of the desorption stage of drying; this phase is prone to generate hot spots, which are brought about by the localized melting of ice crystals not removed in the sublimation stage and the absorption of excess microwave by sorbed water. Comparison of scanning electron microscope micrographs of FD and MFD samples shows that the major dissimilarity between the two samples is in their pore sizes.