中试脉冲喷动床微波冻干山楂干燥特性与品质特性研究

该文针对传统冻干(conventional freeze-drying, CFD)存在的干燥周期长、能耗大及生产成本高等问题,探究中试脉冲喷动床微波冻干(pulse-spouted bed microwave freeze-drying, PSBMFD)山楂的干燥特性与品质特性,分析代替传统冻干进行商业化应用的可行性。以CFD山楂作为对比,研究了两者干燥时间、能耗、山楂品质及干燥均匀性等方面的差异。结果显示,和CFD相比,中试PSBMFD能耗降低72.49%,干燥周期减少62.39%,较好地保留山楂原有风味,所得山楂产品具有多孔结构和较高质构(硬度20.83 N);在水分含量、色差、收缩率方面,中试PSBMFD实现了山楂产品较高的均匀性(>90%);在营养保留方面,中试PSBMFD山楂具有较高的总酚含量[37.03 mg/g干基,以没食子酸当量(gallic acid equivalent, GAE)计]与抗氧化能力。该中试实验结果为PSBMFD商业化提供了有效的理论基础和技术支持。     

饱和蒸汽-热泵组合干燥处理对白萝卜干燥特性及品质的影响

以干燥时间、能耗、VC含量、收缩及复水等为试验指标,研究饱和蒸汽-热泵组合干燥处理对白萝卜干燥特性的影响。结果表明:延长饱和蒸汽处理时间、增加处理次数可明显提高干燥速率,降低干燥时间和能耗。饱和蒸汽-热泵组合干燥与单一热泵干燥相比,白萝卜的干燥时间缩短10%~45%,干燥能耗降低13.67%~44.53%。当饱和蒸汽(处理2次,每次6~8 min)-热泵组合干燥时,白萝卜干制品品质最佳,品质特性中VC含量、复水比、白度分别为50.22 mg/100 g,4.03,63.36;质构特性中硬度、咀嚼性分别为5 457.90,2 829.68 g。在此条件下,白萝卜干制品香气纯正,辛辣味较淡,质地松软顺滑,食用品质最佳。本试验表明饱和蒸汽处理可以显著提高白萝卜的干燥速率,改善其品质。     

冻干条件和添加剂处理对冻干水饺复水性的影响

冻干水饺复水性不理想是限制其应用的主要原因,利用真空冷冻干燥技术对水饺进行了冻干实验,以复水比和感官评价为指标,研究了升华干燥温度、升华干燥时间和解吸干燥温度、解吸干燥时间以及添加剂对冻干水饺复水性和感官指标的影响。实验表明:冻干温度在-45℃,添加剂量0.35%时,冻干水饺的品质和复水性较好;并确定了较佳冻干条件:预冻温度-45℃,升华干燥阶段进行20 h后转入解吸干燥阶段,并持续6 h,此时冻干水饺复水比为1.92,感官指标为72;而添加剂为0.35%时复水比为2.68,感官指标为86。     

高丽菜脉冲喷动床-低频微波干燥品质与能耗

为解决调理蔬菜热风干燥(AD)产品粘连、品质差、能耗高及高污染等问题,以高丽菜为实验原料,利用常压脉冲喷动床-低频微波干燥(PSBLMD)中试平台,进行调理高丽菜PSBLMD品质、均匀度及能耗研究,并与AD方式进行对比分析。结果表明,PSBLMD调理高丽菜(加糖比例15%)抗坏血酸质量浓度、叶绿素质量浓度及复水比(4.69 mg/hg、3.48 mg/hg、26.22)均高于AD高丽菜相应值(1.46 mg/hg、3.14 mg/hg、19.40),PSBLMD样品的水分、色差及收缩率均匀度(91.2%、93.7%、92.3%)达到90%以上;与AD方式相比,PSBLMD不但可以有效解决高糖调理高丽菜干燥过程产品粘结问题,提升干燥产品品质,而且缩短干燥周期50%以上且降低能耗40%以上。     

真空冷冻干燥笋干加工工艺优化研究

本研究以新鲜竹笋为原料,以复水速率(min~(-1))为指标,在单因素实验的基础上,采用正交试验设计,考察柠檬酸浓度、漂烫时间、预冻时间、干燥时间对冻干笋品质的影响;并与热风干燥笋干进行品质对比。结果表明:通过正交试验优化所得的最佳加工工艺条件为:柠檬酸浓度0.1%,漂烫时间为6min,预冻时间为4h,干燥时间为20h,在此最佳工艺条件下测得其复水速率为0.393min~(-1);其水分含量和可溶性糖含量低于热风干燥笋干,色泽、组织状态、复水比、复水速率和蛋白质含量均明显高于热风干燥笋干,说明优化出的最佳加工工艺条件具有可行性。     

不同加工方式对马铃薯原粉特性的影响

以新鲜马铃薯为原料,制备得到马铃薯熟粉、冷冻干燥马铃薯原粉、未经烫漂的热风干燥马铃薯原粉及经烫漂的热风干燥马铃薯原粉,研究不同类别的马铃薯原粉在外观品质、理化特性、功能特性及复水特性等方面的性质。结果表明,不同加工方式下马铃薯原粉的基本理化性质及外观品质均存在显著差异,其中经烫漂的热风干燥马铃薯原粉色泽(L*值为80.78)最佳,为淡黄色粉末,具有高淀粉、高纤维及低脂肪的特点,有利于用作减肥及降血脂健康食品的原料;功能特性结果表明,马铃薯熟粉具有较高的持水能力(3.03±0.01 g/g)、乳化性(21.58%±1.37%)及乳化稳定性(15.98%±0.73%);冷冻干燥马铃薯原粉具有较高的持油能力(3.42±0.08 g/g)和溶解性(16.49%±1.07%);经烫漂的热风干燥马铃薯原粉具有较高的乳化稳定性(16.67%±0.76%)、复水性(复水比为6.43)和复水稳定性(95.76%±0.85%)。同时,结合考察不同加工方式下马铃薯原粉的加工效率与能耗,结果发现,经烫漂的热风干燥原粉具有较高的加工品质且加工能耗低,可作为熟粉的替代品。本研究可为马铃薯不同产品特点选择合适的加工方式,并为马铃薯原粉的研制及代替熟粉的可行性奠定基础。     

不同分切形状对贵州小黄姜真空冷冻干燥效率及品质的影响

目的 比较不同分切形状对贵州小黄姜真空冷冻干燥效率及品质的影响。方法 以贵州小黄姜为原料, 研究真空冷冻干燥过程中姜片、姜丝、姜粒3种不同分切形状干燥效率及小黄姜品质的影响, 采用称量法测定复水率; 色差仪测定色泽变化; 质构仪检测硬度、弹性等参数; 营养成分分别采用Folin-Ciocalteu比色法、硝酸铝显色法和分光光度法测定小黄姜提取物中的多酚、黄酮、多糖和姜辣素含量。结果 切片厚度为3~4 mm的冻干姜片的干燥效率最高、复水率(577.08%)最佳、色差值(5.76)最低、硬度(494.98 g)最小、弹性(0.71 mm)和回复性(0.25 mm)最好、咀嚼性(145.26 g)最高、营养成分保留率最高, 多酚、黄酮、姜辣素、多糖保留率分别为99.35%、70.52%、88.41%、96.27%, 且风味浓郁、感官评分最高。结论 不同分切形状对小黄姜真空冷冻干燥效率及产品品质具有显著影响, 片状的冻干效率更高, 营养成分损失较少, 可获得品质较好的冻干小黄姜。     

芫荽真空冷冻干燥的研究

本文采用真空冷冻干燥技术,探讨了搁板温度、物料重量对芫荽冻干时间、品质及设备生产能力的影响。试验结果表明,搁板设置温度每提高10℃,冻干时间缩短15.68%以上,但温度过高芫荽风味下降,出现干草味;芫荽每增加100g/层,冻干时间延长2.5～3h左右。在温度40℃、芫荽重量400g/层条件下冷冻干燥,冻干时间为12.5h,产品质量优于单纯的真空干燥样品;复水后与新鲜芫荽相对较为接近。     

调理高丽菜脉冲喷动-射频真空干燥的品质研究

为了解决传统高糖调理蔬菜真空干燥过程产品粘连导致干燥产品品质差、成本高、劳动强大及高污染等问题,本文以高丽菜为实验原料,进行不同加糖调理预处理方式对脉冲喷动-射频真空干燥(PSRFVD)蔬菜品质特性及均匀性影响的研究。研究表明:高丽菜采用干法杀青调理预处理结合PSRFVD方式得到的脱水产品中抗坏血酸含量、叶绿素含量、还原糖含量及复水比(24.41mg/100 g、3.12 mg/100 g、61.41%、26.11)均高于热水杀青调理预处理结合PSRFVD的脱水高丽菜相应值(21.68 mg/100 g、2.98 mg/100g、58.11%、21.19);干法杀青调理预处理与热水杀青调理结合PSRFVD脱水高丽菜的水分、色泽及收缩率均匀度分别94.51%、96.31%、92.11%及93.21%、95.63%、91.45%;与传统真空干燥技术相比,PSRFVD技术不但可以有效解决高糖调理预处理高丽菜干燥过程产品粘结问题,提高干燥产品营养成分保留量及均匀度,而且还可以显著地缩短干燥时间(50%)。     

牛脏器真空冷冻干燥最佳工艺条件的确定

以新鲜牛脏器(肝、心、肚、肺)为对象,以干品率为评定指标,研究真空冷冻干燥技术对牛脏器的冻干效果,在单因素试验的基础上,采用正交优化试验对影响牛脏器冻干效果的物料厚度、真空度、干燥时间3个因子进行了优化。结果表明:各因素对干品率的影响大小顺序依次为干燥时间、真空度、物料厚度;最佳冻干参数为干燥时间20 h、真空度20 Pa、物料厚度3 mm。冻干牛脏器水分含量为6.44%,复水比为5.41,复水后牛脏器外形饱满、富有弹性,且未失去其特有的风味,可直接食用。     

Innovative hybrid strategy for efficient production of high-quality freeze-dried instant noodles: Combination of laser with leavening agent

The present study was carried out to improve the drying efficiency and quality of freeze-dried instant noodles by a novel hybrid pretreatment method that combines laser puncturing along with use of a leavening agent mixture. The influence of several variants of this combined treatment on drying time, energy consumption, rehydration behavior and pasting properties of dried noodles as well as the quality parameters of soaked noodles were examined. Results demonstrate that the intervention of laser puncturing treatment and the addition of leavening agent mixture are all positive on reducing drying time and energy consumption of noodles, but the drying enhancement effect of puncturing treatment is better. Combining laser puncturing treatment with leavening agent mixture can further reduce drying time of noodles by up to 34.15% and energy consumption by up to 33.17%. Although all single treatment methods can improve the quality of products including soaking time, rehydration rate and hardness, the effect is unsatisfactory. Hybrid strategies are found to have a synergistic effect on the production of high-quality freeze-dried instant noodles and according to the sensory evaluation results, the optimum conditions are as follows: 0.1  mm perforation diameter, 10 mm spacing between perforations, 2 mm depth and 3% leavening agent mixture (on flour basis).Industrial relevanceDifficult rehydration of products and high energy consumption of the production process are the key issues that limit the industrial production of freeze-dried instant noodles. Laser puncturing treatment and adding a leavening agent mixture can increase the contact area between freeze-dried noodles and water and enrich the internal porous structure of freeze-dried noodles, respectively, which promotes the mass production of high-quality freeze-dried instant noodles.     

EFFECT OF COMBINATION DRYING ON THE PHYSICO-CHEMICAL CHARACTERISTICS OF CARROT AND PUMPKIN

The quality of dehydrated carrot and pumpkin pieces produced by combination drying employing partial freeze-drying and hot air-drying were investigated. The drying rate, the total energy requirement and the physico-chemical properties of the combination dried (CD) products were compared with those of hot air-dried (HAD) and freeze-dried (FD) products. The total carotenoid content of the two vegetables (1050 ppm and 160 ppm) was significantly affected by drying processes. Destruction of carotenoids during storage at different temperatures was less in the CD samples. The HAD vegetables exhibited shrinkage, case hardening and poor rehydration (25 and 28 min in cold water, rehydration ratio 1:2.6 and 1:2.9, respectively). The FD vegetables appeared wholesome, porous, well formed with excellent rehydration features at room temperature (rehydration time 2 and 3 min in cold water, rehydration ratio 1:7 and 1:6.9, respectively). The CD vegetables were comparatively superior to HAD products and were nearer in quality to FD products with respect to appearance, rehydration (9 and 10 min in cold water, rehydration ratio 1:5 and 1:4, respectively). The drying time and total energy for CD processing was 50% less than for FD but similar to HAD. The combination dehydration process is effective in obtaining high quality dehydrated vegetables.     

A novel strategy for improving drying efficiency and quality of cream mushroom soup based on microwave pre-gelatinization and infrared freeze-drying

The present study was carried out to achieve a more efficient dehydration process along with low undesirable quality decrease for cream mushroom soup (CMS) by combining microwave pre-gelatinization (MPG) with infrared freeze-drying (IRFD). Wheat flour was gelatinized using a microwave heating unit for different times, and was used in CMS formulations. Freeze drying (FD) was carried out using conventional as well as IRFD and drying time, energy consumption and product quality characteristics (flavor, viscosity of rehydrate juice; moisture absorption and crystallinity of dried soup solid) of CMS were studied. Compared to FD, IRFD reduced the drying time and energy consumption by 23.81% and 28.43%, respectively. The microwave pre-gelatinization of wheat flour and subsequent use in IRFD, while in comparing with single infrared freeze drying, did not affect drying time and energy consumption; however, it significantly improved the flavor and viscosity of soup upon rehydration, and reduced the tendency to retrogradation. The microwave pre-gelatinization time of 120 s at 8 W/g energy level was found to be the most suitable condition for microwave pre-gelatinization of wheat flour.Industrial relevanceUndesirable decrease of viscosity in starch containing soup and high energy consumption of traditional freeze-drying limit the large-scale industrial production of freeze-dried starch containing product. Therefore, inhibiting viscosity reduction and reducing production cost are the crucial steps for industrial production of freeze-dried cream mushroom soup. Microwave pre-gelatinization and infrared freeze-drying have made outstanding contributions on improving starch stability and reducing drying energy consumption, respectively, which caters to the preferences of industrial production and can be used in industrial production of freeze-dried instant cream mushroom soup.     

不同冻干工艺对冻干米线复水品质的影响

近年来,干制方便米线作为一种方便食品发展迅速,但是干制方便米线存在复水时间长、易糊汤、易断条、口感不理想、质构特性较差等问题。为了改善干制方便米线的这些特性,本研究采用?10、?20和?40 ℃ 三种冻结温度对米线进行真空冷冻干燥,分别得到三种冻干米线FDRN10、FDRN20、FDRN40样品,通过分析冻干米线在不同水温下的复水速度、微观结构、淀粉回生程度和质构特性的变化,探讨了冻结温度对冻干米线复水品质的影响。结果表明,在相同水温下经相同浸泡时间复水处理后,FDRN10含水量最高,表明其复水速度最快。外表面和横断面微观结构观察发现,三种冻干米线样品中FDRN10结构最为疏松,孔隙最大,为72.58 μm,是孔隙最小的FDRN40的4倍,结构吸水性最好。进一步的DSC检测发现FDRN10焓值最高,为92.98 J/g,焓值最低的FDRN40为12.39 J/g,表明FDRN10在三种冻干米线样品中回生程度最高,淀粉吸水溶胀最慢。同时硬度分析结果表明,在相同浸泡时间下FDRN10硬度值随水温的升高而降低,采用70 ℃热水复水8 min,FDRN10质构特性最接近鲜湿米线。以上结果表明,冻结温度和复水温度对冻干米线品质形成起到关键作用,本研究结果可为方便米线工艺改进提供理论依据。     

干燥方式及碱液处理对鲜枸杞干燥特性和品质的影响

为了缩短鲜枸杞干燥时间,降低能耗,提高枸杞干制品品质,采用清水和不同质量分数（2%、4%和6%） 的Na2CO3溶液对枸杞进行前处理后,分别进行热风和热泵干燥,测定并分析了所获得枸杞干果的干燥速率、色 泽、复水率以及主要营养成分（多糖、总类胡萝卜素、黄酮）含量。结果表明：Na2CO3前处理能使枸杞表皮蜡质 层变薄、断裂,形成水分通道,进而缩短枸杞干燥时间,较为适宜的Na2CO3质量分数为2%。在干燥效率方面,热 泵和热风干燥没有显著性差异,但是在干燥产品品质上,热泵干燥要明显优于热风干燥。相对于恒温恒湿干燥, 分阶段变温干燥在保证干燥产品品质的同时,加快干燥速率,缩短干燥时间。因此枸杞干燥的最适工艺参数为 2% Na2CO3前处理,干燥温度40 ℃（2 h）-45 ℃（4 h）-50 ℃（6 h）-55 ℃（10 h）,干燥相对湿度40%的热泵干 燥。此工艺条件下枸杞干燥时间为22 h,干燥枸杞色差值为15.09,复水率为2.35 g/g,多糖含量为10.29 g/100 g,黄 酮含量为0.43 g/100 g,总类胡萝卜素含量为1 503.13 μg/g。     

热泵式长豇豆干燥工艺优化

为保证热泵干燥后长豇豆产品的复水性和色泽等品质参数良好,同时降低豇豆干燥过程中的能量消耗,提高豇豆干燥生产的效率,采用Box-Behnken试验设计,分析干燥温度、漂烫时间和铺料密度3 个因素对豇豆产品的复水率、色差、单位耗能量和耗时4 个参数的影响,建立多元回归模型,并对干燥工艺参数进行优化,得到热泵式长豇豆干燥工艺的最佳条件为漂烫时间3 min、铺料密度2 kg/m2、干燥温度50 ℃。在该工艺条件下,实际测得长豇豆复水率1.15,色差值22.39,单位耗能量14.31（kW·h）/kg,耗时7 h,与预测值误差极小,为豇豆在实际热泵式干燥设备生产加工中的应用提供一定的理论依据。     

超声辅助渗透处理对冷冻干燥双孢蘑菇冻干效率和品质的影响

为了在生产高品质冷冻干燥产品的同时进一步降低干燥过程中的能耗与成本,选取双孢蘑菇为研究对象,以冷冻和冷冻干燥过程中双孢蘑菇的共晶点、共熔点、冻干温度及冻干产品的质构、微观结构、色泽和营养品质为考察指标,研究普通渗透和超声辅助渗透处理对冷冻干燥双孢蘑菇冻干效率和品质的影响。结果表明,与新鲜样品相比,经超声辅助渗透处理45 min后,样品冷冻时间和冷冻干燥时间分别缩短了21.24%和28.62%,并且其冻干产品的可滴定酸、总蛋白质以及多酚等营养物质的保留率高于普通渗透120 min处理组。此外,与普通渗透120 min处理组相比,超声辅助渗透45 min处理组冻干样品复水比、硬度更高,其微观结构更加接近于未经渗透处理的冻干样品。     

响应面法优化微波-热风脱水冻豆腐干燥工艺及其品质评价

为解决冻豆腐储运成本高、耗能大的问题,本研究采用微波与热风联合干燥制备脱水冻豆腐。通过考察含水率和复水率,确定了先微波后热风（M-H）的干燥顺序。以干燥速率、复水率及色差为考察指标,通过单因素和响应曲面实验优化工艺条件为,以微波功率516 W进行微波干燥、在转换点含水率为37%时转热风干燥,热风干燥的温度为68 ℃。干燥后的脱水冻豆腐经复水后,其弹性、咀嚼性和内聚性分别为0.963 mm?1、5810 g、0.79,复水率达到531.97%,色泽变暗;SEM表征及切面结构结果显示,经过干燥后的冻豆腐凝胶网络结构更加紧凑,孔隙变得更加均匀。     

干燥方法对柠檬果胶理化性质影响

为探究不同干燥方法对柠檬果胶理化性质的影响,实验以柠檬干渣为原料制备果胶,固定提取和浓缩条件,采用热风干燥、真空干燥、冷冻干燥及喷雾干燥等干燥方法对柠檬果胶进行干燥处理,研究不同干燥方法对柠檬果胶得率、半乳糖醛酸、酯化度、能耗、复水比、凝胶强度及果胶结构的影响,采用变异系数法对各指标加权评分,确定柠檬果胶最佳干燥方法。结果表明:所有干燥后的果胶半乳糖醛酸含量均达到国标65%的要求;酯化度均大于50%,傅立叶红外光谱(Fourier Transform Infrared Spectrometry,FTIR)显示,不同干燥方法干燥后的果胶均具有果胶的特征官能团,说明所用干燥方法不会对果胶结构产生影响。不同干燥方法干燥后的果胶各指标均存在显著性差异(P<0.05),加权综合评分最高的方法是:60℃真空干燥,所得柠檬果胶得率、半乳糖醛酸、酯化度、单位能耗、复水比、凝胶强度分别为17.84%、82.44%、73.16%、28.13 kJ/g、5.36%、149.71 g。真空干燥所需设备简单,且能耗相对较低、产品品质好,对柠檬果胶制备研究具有重要意义。     

牡蛎冷冻干燥后复水特性及微观结构的研究

研究牡蛎冷冻干燥后的复水特性,将新鲜牡蛎分为直接冻干组(Fresh+FD组)、预煮处理后冻干组(Boiled+FD组)和自然干燥组(Fresh+ND组),考察干燥后牡蛎的干燥比、复水比、复水率和微观结构的差异。结果表明:两冻干组牡蛎的含水量远低于自然干燥组,在常温和沸水中的复水比和复水速率均大于自然干燥组,冷冻干燥更有利于牡蛎中水分的去除和复水;干燥后牡蛎闭壳肌微观形态优劣程度依次为Fresh+FD组>Boiled+FD组>Fresh+ND组,其中Fresh+FD组闭壳肌纤维细长、舒展,间隙均匀,Fresh+ND组闭壳肌纤维束堆叠,组织致密;常温复水80min,两冻干组牡蛎的复重系数和复水率均高于自然干燥组。