LF-NMR动态分析4种干燥方式下鱿鱼干的复水特性

以鱿鱼为研究对象,采用自然晒干、热风干燥、热泵干燥、真空冷冻干燥4种干燥技术干制鱿鱼,结合鱿鱼干的肌纤维微观结构和复水率,通过低场核磁共振(LF-NMR)动态分析鱿鱼干复水过程的水分迁移和分布,探讨干燥方式对鱿鱼干复水的影响。结果表明,4种干燥方式中,真空冷冻干燥的鱿鱼干水分含量最低,氧化程度也最低(比其它3种处理的低1.5~6.7倍)。电镜扫描图显示鱿鱼干肌纤维内部有大量疏松多孔的蜂窝状结构,且真空冷冻干燥复水最快。复水过程,部分结合水向不易流动水迁移,不易流动水含量明显增加,且占比90%以上,自由水含量也有所提升。LF-NMR分析也表明真空冷冻干燥的鱿鱼干复水效果最好,复水后可截留更多的自由水。热泵干燥的鱿鱼干复水效果与自然干燥接近,热风干燥的复水率最差。干燥方式对干制品复水效果影响明显,真空冷冻干燥和热泵干燥技术有利于水产品干制。     

不同干燥处理方法对鸡肉丁的干燥效果

分别采用热风干燥法(hot air drying)、真空冷冻干燥法(vacuum freeze drying)和微波-热风耦合干燥法(combined microwave and hot air drying)干燥鸡肉,探究3种不同干燥方法对鸡肉丁的干燥曲线、色泽和水分活度、微观结构、复水性、复水后鸡肉丁质构特性和感官评定等指标的影响。结果表明,真空冷冻干燥后鸡肉色泽与水分活度明显优于其他2种干燥方式;环境扫描电镜(environmental scanning electron microscope, ESEM)观察结果表明,干燥后样品微观结构均发生一定程度收缩,真空冷冻干燥收缩最小,微观结构清晰饱满,与未经干燥样品的微观结构最为接近;真空冷冻干燥后的鸡肉复水时间最短,复水率最大,复水后真空冷冻干燥样品表现出良好的质构特性与感官品质,其次为微波-热风耦合干燥,热风干燥效果最差。     

不同干燥方法对乌贼品质及微观结构的影响

为了解不同干燥方法对乌贼干后品质及微观结构的影响,采用自然晾晒干燥、热风干燥和真空冷冻干燥3种方法对乌贼进行处理,研究其对乌贼感官特征、色泽、收缩率、风味、甲醛含量和微观结构的影响,以及在后续复水过程中复水率和复水完成后质构参数的变化。结果表明,干制后乌贼的收缩率变化为:自然晾晒干燥热风干燥真空冷冻干燥,且差异显著(P0.05)。真空冷冻干燥的乌贼在色泽、复水率方面优于其他两组,在第9小时的纯水复水率可达524.25%,为自然晾晒干燥组的2.5倍,而在质地和风味方面的品质一般,其微观肌肉纤维形变较小,纤维间孔径较大;热风干燥后的样品在感官、质地以及风味方面具有显著优势,呈味氨基酸含量总和达1 519.20 mg/100 g,显著高于其他干燥组(P0.05),但样品中的甲醛含量较高,为260.83 mg/kg,是新鲜样品的4.7倍,且肌肉纤维形变大,排列致密;自然晾晒干燥的乌贼肌肉纤维形变较小,排列较致密,其甲醛含量较低,仅为22.06 mg/kg,感官品质和色泽还有待进一步提高。     

微波气流预干燥和微波真空组合干燥生产甜瓜片

研究了微波气流预干燥(MAD)和微波真空(MVD)组合干燥甜瓜片,表明这是一种有潜力的干燥方法。样品先通过微波气流干燥脱去一些自由水,然后通过微波真空干燥到最终水分含量低于7%(湿基)。甜瓜片利用微波气流(MAD)和微波真空(MVD)组合干燥后测得Vc保留率和物性(收缩率,色差,质地和复水率)然后同冷冻干燥(FD)、微波气流干燥(MAD)、气流干燥(AD)和常规热风干燥(HAD)分别进行比较,表明,MA+MVD方法干燥的甜瓜片的Vc保留率接近冻干的甜瓜片,大大优于传统的热风干燥。当前方法干燥的样品表现出的复水率、色差、质构与冻干的产品非常相似,但是出现了明显的膨化现象,然而,这正是生产果蔬脆片所期望得到的结果。     

真空冷冻干燥对牡蛎品质的影响

我国牡蛎产量丰富,除部分鲜销外很多加工为干制品,然而传统牡蛎干制品复水性差、产品附加值低。为了得到高品质的牡蛎干制品,本研究对牡蛎进行真空冷冻干燥加工,并对冻干加工牡蛎的复水性、质构和蛋白、脂肪及部分滋味成分含量的变化情况进行探讨。研究结果表明:牡蛎的共晶点和共熔点温度分别为-25℃和-17.5℃,牡蛎在-30℃~-35℃条件下预冻2 h,在冷阱温度达到-40℃后在真空度20 Pa条件下干燥15 h得到干品;与对照产品(市售蚝干)相比,冻干牡蛎复水性较好,其在20 min即可复水完全,复水比为3.68;冻干牡蛎的质构也优于对照,除脂肪含量较低外,蛋白质和几种滋味成分含量也均高于对照。由此可见,真空冻干燥不仅可以减少牡蛎干制时的蛋白损失,且能够较好保持质构和原有风味,可以用于高品质牡蛎干制品的加工。     

不同干燥方式对茶树菇品质的影响

以新鲜茶树菇为原料,先采用热风干燥进行部分失水后,再采用冷冻干燥或真空干燥至足干,通过对干制品进行感官评价、色差、复水比及Vc含量的测定,比较单一与复合干燥方式的茶树菇的品质。结果表明:在外观品质、总色差值和复水比上,冻干样品是最好的,其次是热风+冻干复合样品,其收缩度小于热风、真空及其复合干燥方式,真空干燥褐变和收缩最严重,但其香味较浓;样品Vc含量,冻干热风+冻干真空干燥热风干燥。     

干燥方式对香菇品质特性及微观结构的影响

为了分析常用的3种干燥方式对香菇干制品品质的影响,以新鲜整香菇为原料,采用三段式微波真空冷冻干燥(three-stage microwave vacuum freeze drying,TS-MVFD)、冷冻干燥(freeze drying,FD)、热风干燥(hot airdrying,HAD)技术干燥加工,探讨不同干燥方式下香菇干制品的干燥特性、营养成分、微观结构,并通过标度法定量分析3种香菇干制品复水熟制后的感官特性。结果表明,香菇脱水至水分质量分数低于13%,TS-MVFD、FD与HAD的干燥时间分别为5、14 h和8 h。复水120 min后,TS-MVFD香菇干制品复水比(7.1)明显高于FD(6.0)、HAD(4.4)样品;复重系数(91.40%)、菌盖色泽和总糖(60.21 g/100 g)、粗多糖(7.41 g/100 g)、游离氨基酸(3.44 g/100 g)含量与FD香菇干制品差异不大;FD香菇截面呈多孔性的蜂窝状网状结构,微孔分布均匀;TS-MVFD香菇微观结构与FD相似,而且微孔孔径稍大;HAD香菇截面结构层叠,细胞壁坍塌严重。复水熟制后,TS-MVFD香菇样品的风味、口感明显优于HAD和FD干燥产品。综上,TS-MVFD是一种有推广价值的香菇干燥方式。     

不同干燥方式制备方便米饭的品质比较

比较研究热风干燥、微波干燥和真空冷冻干燥对方便米饭复水时间、复水率、表面微观结构和感官品质的影响。结果表明:热风干燥制备方便米饭最佳干燥条件为干燥温度60C、干燥时间120min微波干燥最佳干燥条件为干燥功率450W、干燥时间25min真空冷冻干燥最佳干燥条件为板层控制温度60C、干燥时间15h。对3种干燥方式制备的方便米饭表面扫描电镜分析表明:真空冷冻干燥制备的方便米饭表面纹理有规则,较少裂痕,表面空隙致密均匀,具有最利于复水的表面微观结构;经真空冷冻干燥的方便米饭,复水时间5min,复水率可达3.4,复水特性与感官品质均优于其他两种干燥方式制备的方便米饭。     

高菜真空冷冻与热风联合干燥工艺研究

研究真空冷冻(FD)与热风(AD)联合干燥腌制调味高菜,以期找到能生产优质节能的脱水腌制调味高菜的联合干燥方式.将联合干燥得到的产品分别与AD和FD干燥得到的产品进行总能耗和物理特性(包括复水比、色泽、体积密度以及产品的硬度和脆度)的比较,研究结果表明,FD20h+ AD1h的产品与FD的产品在品质上无显著差异,比FD干燥方式节省能耗约33％;AD1h+ FD22h比FD干燥方式节省能耗约22％,与FD的产品在色泽上有显著差异.两种联合干燥方式的产品最终湿基水分含量均达到了小于8％的要求,复水比均大于5.     

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。     

基于变异系数权重法评价三种干燥方法对牡蛎干品质的影响

以新鲜牡蛎为原料,通过鼓风干燥、真空干燥、真空冷冻干燥3种方法进行干燥,并对干制品的营养成分、色泽、复水率、质构、生产周期、能耗和感官评分进行测定,利用变异系数权重法得到3种牡蛎干制品的综合评分,以确定最佳干燥方法。结果表明:真空冷冻干燥可较好保留产品各种营养成分,其制得的牡蛎干色差最小,复水率与质构特性(硬度、咀嚼性和胶着性)显著优于鼓风干燥和真空干燥(p<0.05),但生产周期最长,能耗最高。真空干燥牡蛎干体型完整,有光泽,质地适中,鲜香味浓,感官评分最高。L*、硬度、咀嚼性、胶着性和干燥能耗在牡蛎干品质评价中占较大比重,权重值分别为0.105、0.112、0.121、0.109、0.120;综合评分结果为:真空冷冻干燥(0.780) > 真空干燥(-0.074) > 鼓风干燥(-0.707),真空冷冻干燥牡蛎干品质最佳。变异系数权重法可用于牡蛎干品质评价,为其在水产品加工技术优选中的应用提供理论参考。     

干燥方式对复水香菇感官、质构及营养品质的影响

为获得复水性较好的干香菇,研究了热风干燥（hot-air drying,HAD）、中短波红外干燥（infrared radiation drying,IRD）和真空冷冻干燥（freeze drying,FD）香菇的复水特性及复水后的综合品质。结果表明：FD香菇具有均匀的多孔结构,使得干香菇的复水速率明显高于HAD香菇和IRD香菇,复水60?min即可达最大复水体积比（9.22）,且复水香菇的外观与鲜样接近。同时,复水后FD香菇的剪切力（1?352.99?g）和咀嚼性（232.54?g）最小,表明其质地柔软、易被切分。此外,FD复水香菇和其他两种复水香菇具有相似的电子鼻响应值曲线,表明其香气无差异。复水时FD香菇的蛋白质和VB2的溶出率最高,分别为0.42?mg/g和0.71×10－3?mg/g,说明FD复水香菇富含营养成分,且加工时较易溶出。综上,FD可作为一种较好的干燥方式来制备复水性较好的高品质香菇。     

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.     

Viability, efficacy, and storage stability of freeze-dried biocontrol agent Candida sake using different protective and rehydration media

Viability, efficacy against Penicillium expansum on Golden Delicious apples, and storage stability of freeze-dried Candida sake strain CPA-1 were studied. The effect of several protective agents and rehydration media was investigated in the freeze drying of C. sake. Skimmed milk at 10% concentration was a good rehydration medium for all protectants tested. In general, good viability results were obtained when the same solution was used as a protectant and as a rehydration medium. The best survival was obtained when C. sake cells were protected with 10% lactose + 10% skimmed milk and rehydrated with skimmed milk (85% viability). The potential for biocontrol of the best freeze-dried treatments against P. expansum on apples was compared with that of fresh cells. Freeze-dried treatments at 1 x 10(7) CFU/ml reduced the incidence of decay by 45 to 66%. The best biocontrol effect was obtained with cells that had been freeze dried using 10% lactose + 10% skimmed milk as a protectant and 1% peptone as a rehydration medium, with a 66% reduction in rot incidence. However, in all treatments, the efficacy of freeze-dried cells was significantly lower than fresh cells. The stability of freeze-dried samples decreased during storage and was influenced by storage temperature. In the best treatment, storage of C. sake cells for 60 days at 4 degrees C resulte in final concentrations of 2.5 x 10(8) CFU/ml, which was a 10-fold reduction in relation to the initial starting concentration of cells prior to freeze drying.     

Studies on different combined microwave drying of carrot pieces

Three different combined microwave (MW) drying methods were compared, namely microwave‐assisted vacuum drying (MWVD), microwave‐assisted freeze drying (MWFD), microwave‐enhanced spouted bed drying (MWSD), in terms of drying rate, drying uniformity, product colour, rehydration ratio, retention of β‐carotene and vitamin C, and energy consumption. The drying rate of MWVD and MWSD were much faster than that of MWFD. The largest drying rate was obtained in MWSD with 3.5 W g^?1. In general, the colour of MWSD products was very uniform. Rehydration ratio of MWFD carrot pieces was almost the same as the freeze‐dried (FD) products and better than MWVD and MWSD products. In addition, the highest retention of carotene and vitamin C was observed in MWFD carrot pieces. No significant differences were observed in carotene and vitamin C between MWVD and MWSD products. However, the energy consumption in MWFD was the highest.     

Comparison of four drying methods for re-structured mixed potato with apple chips

The effects of microwave-freeze drying (MFD), freeze drying (FD), microwave vacuum drying (MVD) and vacuum drying (VD) on texture, color, rehydration, sensory, microstructure and other quality parameters of re-structured chips made by blending apple with potato were studied. MFD chips had the best quality and these products were preferred by consumers. The drying time for MFD was lower than that for FD. The drying time for MVD was the shortest and the energy consumption was also the lowest. Microwave drying not only reduces the drying time but also improves the quality of dried products. Both MFD and MVD techniques are found to be suitable for production of re-structured chips of varying grades.     

小麦粉和4种干燥方式制备的板栗全粉的基本品质比较

本文对比研究了四种板栗全粉(自然晾干、鼓风干燥、热泵干燥、真空冷冻干燥方式制备)、低筋小麦粉、高筋小麦粉的基本物理特性、营养特性及加工特性。结果表明:板栗全粉主要成分为淀粉和总糖(总含量占比70%以上),不同干燥方式对板栗全粉各项指标影响程度不同,其中真空冷冻干燥板栗全粉的L值最大、粒径主要分布范围最接近小麦粉,且7种必需氨基酸占总氨基酸的比例(36.90%)、多酚(1.49 mg/100 g)与V_C(11.7 mg/100 g)均最高。小麦粉中赖氨酸相对不足(RCAA<1),但不同干燥方式板栗全粉中赖氨酸、苏氨酸含量相对过剩(RCAA>1)。因此,不同干燥方式所得的板栗全粉应用于小麦粉制品时,能有效丰富产品的氨基酸以及抗氧化营养成分,可优选真空冷冻干燥方式制备的板栗全粉。     

真空冷冻干燥南美白对虾干燥模型及品质研究

目的:以南美白对虾为研究对象,探究真空冷冻干燥南美白对虾的干燥特性,并建立干燥模型。方法:通过干基含水率和干燥速率探究干燥温度和装载量对干燥特性的影响并进行干燥模型拟合,同时基于收缩率、复水率、质构、感官评定对比分析真空冷冻干燥和热风干燥对对虾品质的影响。结果:干燥温度和装载量是影响干燥速率的关键因素,随着干燥温度的增加和装载量的减少,干燥时间缩短;而干燥速率随着干基含水率的下降呈现下降趋势。优化三种干燥模型,发现Page模型能更好的拟合真空冷冻干燥对虾的干燥特性。此外,与传统热风干燥相比,真空冷冻干燥对虾干制品具有低收缩率和高复水率特性(分别达到30.11%±0.04%、74.98%±0.01%),硬度、粘性和咀嚼性更低,并且色泽和感官上均优于热风干燥对虾干制品。结论:通过真空冷冻干燥技术可以获得品质更佳的南美白对虾干制品。     

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.