刺参远红外干燥实验研究

为寻找新型刺参干燥技术,本文采用实验方法研究了刺参在远红外干燥条件下的干燥特性,分析了相对含水率、干燥速率、收缩率和复水率等参数的动态变化规律,以及干燥温度对干制刺参品质的影响,比较分析了13种预测刺参远红外干燥特性的薄层干燥模型。结果表明,温度对刺参相对含水率、干燥速率、收缩率和复水率均有重要影响。在干燥初期,刺参的干燥速率与温度呈正相关,而到了干燥中后期,温度对干燥速率的正相关影响不太明显,甚至温度低的干燥速率反而更高。刺参收缩率和复水率均随干燥温度的升高逐渐增加,且温度越高增加越明显。60℃条件下干燥时间为14 h,干制品复水率可达5.0,且质量较好,是较理想的远红外干燥温度值。在干燥模型方面,Two-term exponential模型精度最好,R2可达0.993,能更好地的预测远红外干燥中刺参相对含水率的变化。     

黄秋葵热风与远红外干燥特性、动力学及品质的比较

为获得黄秋葵干燥工艺条件,选取不同干燥方式、干燥温度对黄秋葵进行干燥,研究不同干燥工艺条件对干燥特性、动力学和品质的影响。结果表明：热风干燥速率受干基含水率的影响大,远红外干燥速率受干基含水率的影响小。Midilli 模型能准确描述黄秋葵热风和远红外干燥过程。在相同温度下,热风干燥的有效水分扩散系数比远红外干燥的大0.52～1.10 倍,热风干燥所需活化能比远红外干燥所需活化能低5 481.76 J/mol。干制品的VC 降解、复水比和硬度受温度和时间累积效应的影响。以干燥特性、动力学和干制品品质为指标,基于主成分分析获得黄秋葵干燥条件,热风温度70 ℃,干燥时间为300min,有效水分扩散系数为1.36×10-9m2/s,所得干制品VC 含量7.71mg/100g、复水比6.03、硬度3.25 N。     

干燥方法对速食薏米粉干燥特性与品质的影响

采用微波干燥(MD)、微波对流干燥(MCD)、热风干燥(HAD)和传统烤制法(TR)4种干燥方法对高压汽蒸熟制薏米进行干燥制备速食薏米粉,考察4种干燥方法对薏米的干燥特性,并比较其对薏米粉色泽、营养成分、冲调特性和感官评价的影响。结果表明:在干燥特性方面,MCD所用时间最短,仅为26 min,其次为TR,为35 min,HAD所用时间最长,为90 min,且MCD的平均干燥速率最高。在色泽方面,选用MCD方法处理的样品颜色偏黄,更接近于新鲜薏米粉的色泽。在营养化学组分特性方面,干燥后的薏米粉中灰分、粗脂肪、蛋白质、总糖和还原糖的含量均有损失,其中MD对灰分和总糖损失最少;MCD对蛋白质和还原糖的保留最好;TR干燥后的粗脂肪含量最高为7.02 g/100 g。冲调特性方面,MCD制备的产品堆积密度最低,休止角最小,流动性最好,水合能力最高;TR制备的薏米粉的润湿下沉性和分散性时间最短,结块率和吸湿率最低。MCD 样品获得最高的感官评价分84.8分。综合评价相对HAD和TR,MCD干燥速率快、品质好。     

远红外辅助热风干燥对秋刀鱼片干燥特性及品质的影响

为探究远红外辅助热风干燥对秋刀鱼片干燥特性和品质的影响,采用远红外辅助热风干燥和热风干燥工艺在50、60、70、80和90 ℃下对秋刀鱼片进行脱水处理,并观察其品质变化情况。结果表明:为使秋刀鱼片的干基含水率降低至43%以下,50~90 ℃热风干燥所需的干燥时间分别为570、435、282、225、208 min,远红外联合热风干燥所需时间为510、395、258、204、186 min,提高干燥温度有利于缩短干燥时间和提高干燥速率,且远红外联合热风干燥具有明显的干燥优势。低场核磁共振的检测结果显示,干燥过程秋刀鱼片中的不易流动水转化为自由水向外扩散进而实现干燥的目的。在干燥品质方面,干燥后秋刀鱼片的红度a^*值和黄度b^*值分别增加至4.85~8.98和12.08~16.01;随干燥温度的增加,硬度、咀嚼性、回复性等质构指标和气味、鲜味、咀嚼性等感官评分呈上升趋势,亮度L^*值、TBA值和组织形态评分呈下降趋势,色泽评分则表现为先上升后下降趋势。和热风干燥相比,远红外辅助热风干燥秋刀鱼片在色泽、质构特性方面的品质较好,组织形态、气味等方面的感官评分较高,但在TBA值方面两种干燥方式没有表现出显著性差异(P>0.05)。

     

不同香菇干燥方式的干燥特性和干品品质对比研究

干制香菇是延长香菇保质期的有效方式之一,采取三种单一干燥方法和两种组合干燥方法对香菇进行干燥处理,研究了香菇干燥过程中的干燥动力学特性和干制品品质的变化。实验结果表明:从干燥效率和失水速率来看,三种干燥方法从优到次依次为热风干燥、普通烘箱干燥、真空干燥;从干制品外形品质来评价,从优到次依次为真空干燥、热风干燥、普通烘箱干燥。而真空与热风联合干燥香菇是有应用价值的,联合干燥后的干香菇产品品质远优于热风干燥,且比单一的真空干燥缩短干燥时间。      

苹果片双段控湿干燥特性及干燥品质工艺研究

为缩短苹果片干燥时间和控制产品品质，以多参数可控薄层干燥试验系统为手段，探索双段控湿工艺对干燥特性和品质的影响规律。以热风恒湿20%下干燥特性和品质为对照，系统研究了双段控湿干燥工艺参数热介质相对湿度、温度、流速和预处理蒸烫时间对干燥特性和品质特性的影响，品质特性以总色差ΔE^*值、维生素C含量、5-羟甲基糠醛(5-hydroxymethylfurfural, 5-HMF)含量作为衡量指标，并采用正交试验优化了工艺参数。结果表明，在试验范围内，双段控湿相对湿度对干燥特性和干燥品质均有显著影响(P<0.05),较优双段控湿条件为30%保持30 min调至20%,与恒湿干燥20%相比较，所需时间缩短了16.66%,产品ΔE^*降低了39.71%、维生素C含量提高了15.20%、5-HMF含量与之无差异；双段控湿制干工艺参数介质温度、流速和预处理蒸烫时间对干燥特性和品质特性也有显著的影响(P<0.05)。双段控湿干燥工艺优化参数为：双段控湿30%(30 min)调至20%、蒸烫时间2 min、介质温度65℃、速率0.7 m/s,此条件下制得...     

热风风速和相对湿度对扇贝柱干燥特性及品质的影响

本试验以海湾扇贝柱为原材料,进行薄层干燥试验,研究恒定风温下不同热风风速、相对湿度对产品干燥特性和品质的影响。测定干燥过程中水分含量和水分活度（Aw）的变化,并对所得产品的收缩率、复水率、色泽、质构等品质特性进行了比较分析。结果表明, 整个干燥过程均处于降速干燥阶段,起始阶段干燥速率下降最快,随着干燥时间的延长,干燥速率逐渐平缓。提高风速、降低热风相对湿度都可以显著缩短干燥时间,水分活度（Aw）下降速也越快。不同热风风速和相对湿度对干贝的质构特性、收缩率和复水率也有显著影响,但是对干贝色泽影响并不显著。综合考量干燥速率和干制品品质,选择热风风速为0.8~1.2 m/s、热风相对湿度在8%左右为较适宜的海湾扇贝柱热风干燥条件。     

玉米薄层干燥特性对比试验研究

在热风薄层干燥试验平台上对玉米进行薄层干燥对比试验,采用单因素试验与正交试验相结合的方法,以玉米发芽率、裂纹率及干燥速率为指标,研究影响玉米干燥特性的主次因素,确定最优干燥工艺参数。试验结果表明:在玉米原始含水率不变的情况下,热风温度的影响最为显著。     

气体射流冲击干燥花生实验工艺的优化研究

目的 探究气体射流冲击干燥装置对花生干燥特性和营养品质的影响及优化干燥工艺。方法 利用气体射流冲击干燥装置研究不同因素(干燥温度、风速、喷射间距)对花生的干燥特性、发芽率、营养品质的影响。以上述三因素进行单因素实验,分析实验结果确定待优化区间,并运用Box-Behnken响应面实验设计和隶属度综合评分法,对干燥工艺进行综合优化。通过数据分析与比较,得出最优干燥工艺。结果 温度45℃、风速5 m/s、喷射间距15 cm为最优干燥工艺。此时花生干燥速率为0.09 (g?g-1?min-1)、发芽率为95%、亚油酸含量为34%。结论 该工艺相比其他工艺,既能保证花生营养品质、发芽率,又可实现快速干燥,为气体射流冲击干燥技术应用于花生干燥中提供了一定的理论依据。     

不同干燥方法对三华李片干燥特性及营养成分的影响

为探究不同加工方法对三华李片干燥速率及营养品质影响,采用热风干燥、红外干燥和微波干燥方法对三华李片进行处理,并探讨3种干燥方法对三华片色泽、微观结构、硬度、弹性、咀嚼性、复水比、体积收缩率及总糖、总酸、总酚和维生素C等营养品质影响。结果表明,微波干燥速率较大,干燥时间最短,红外干燥速率最小,干燥时间最长。红外干燥色差较大,组织结构和体积收缩严重,复水性、质构特性及适口性较差,营养损失严重;热风干燥色泽明亮,结构紧密,表面平整,存在裂缝,复水性、硬度、咀嚼性适中,其弹性最好,总糖含量最高,相对于红外干燥,其营养含量保持较好。微波干燥整体色泽良好,结构疏松,体积收缩率、硬度值（2 829.76 g）、咀嚼性（2 535.03 J）,复水比（2.86）、总酸含量（5.32 g/100 g）、维生素C含量（18.28 mg/100 g）、总酚含量（32.12 mg/100 g）等均优于红外干燥和热风干燥,总糖含量（14.16 g/100 g）适中。综合分析,微波干燥优于其他两种干燥方法,可为三华李加工提供一种较好的备选方法。     

Effect of shrinkage on isothermal drying behavior of 2-phase olive mill waste

The objective of this study was to determine the drying behavior of 2-phase olive mill waste (2POMW) under isothermal microwave-convection drying conditions. 2POMW samples were dried in a thin layer in a variable-power pilot microwave oven with impinging air, using a feedback controller to maintain sample temperature at one of four levels. Moisture loss and shrinkage of the samples were recorded during drying. The apparent diffusion coefficient of water was determined for the first falling rate period both with and without shrinkage. Apparent diffusivity was 28% lower when shrinkage was considered. Thus, shrinkage plays an important role in the drying behavior of this agricultural residue.     

酿酒葡萄皮渣红外干燥研究

对酿酒葡萄皮渣进行红外干燥研究,以期优化葡萄皮渣的干燥工艺,也为其它物料的红外处理干燥提供理论基础。实验对自然晒干、连续红外干燥、间歇红外干燥以及红外对流两步干燥进行研究,对每种干燥方法的干燥特征、灭菌效果以及干燥质量进行比较分析,并且对不同干燥处理的葡萄籽的超微结构进行观察。结果表明,连续红外干燥的干燥速率最高;除自然晒干和IR9min-CD55℃外,所有干燥方法均具有较好的灭菌效果;皮渣的总多酚和原花青素在所有干燥过程中都有一定损失,连续红外干燥对总多酚和原花青素具有较好的保护作用;红外干燥的葡萄籽的组织之间出现较多的孔隙,而自然晒干和对流干燥的葡萄籽组织间没有或有少量的孔隙。综上,连续红外干燥适合酿酒葡萄皮渣的干燥处理,具有高干燥品质。      

Production of bread crumbs by infrared-assisted microwave drying

This study is aimed to investigate the possibility of using infrared-assisted microwave drying for production of bread crumbs and to determine drying conditions in halogen lamp-microwave combination oven to produce bread crumbs with the highest quality. Bread crumb dough were dried from about 40.9 to 8% moisture content by conventional, microwave, infrared and infrared-assisted microwave drying separately and in combinations. Halogen lamp and microwave power levels of 30, 50 and 70% were used. Percent reduction in the drying time were 80.2–94.0 for infrared, 96.5–98.6 for microwave and 96.8–98.6 for infrared-assisted microwave drying. ΔE values were lower in microwave drying and higher in infrared drying. Infrared-assisted microwave dried crumbs generally had similar color values with the conventionally dried ones. Effect of power on color change was not observed. All drying methods were found to be effective in increasing water binding capacity, which increased with microwave power in microwave drying but the influence of halogen lamp power was not seen in infrared drying. At fixed microwave (halogen lamp) powers increase of halogen lamp (microwave) power did not affect the water binding capacity in infrared-assisted microwave drying.     

热泵干燥温度对柿子片干燥特性及品质的影响

目的:探明热泵干燥温度对柿子片干燥特性和品质的影响。方法:以柿子为原料,研究干燥温度对柿子片干燥时间、干燥速率,以及干制品色泽、硬度、复水率、单宁、总糖、维生素C和总酸的影响。结果:当热泵干燥温度为65℃时,柿子片干燥速度快,干燥时间短,此时干燥产品色泽鲜艳,与鲜果色泽相近,复水性能好,硬度最低,口感最好,总酸和维生素C含量最高,总糖等营养成分含量适中。结论:柿子片的最适热泵干燥温度为65℃。     

Effects of ultrasound and infrared assisted conductive hydro-drying,freeze-drying and oven drying on physicochemical properties of okra slices

Okra (Abelmoschus esculentus) is a nutritious vegetable but it is highly perishable and drying is one of the best methods for its preservation. Ultrasound and infrared assisted conductive hydro-drying (UIACHD) is a new patented drying method that can dry food materials with high quality and high energy efficiency. In this study, okra slices were dried using UIACHD with different settings and also by freeze-drying and oven drying. The UIACHD drying curves, moisture content, color, vitamin C content, hydrocolloids rheology and microstructure of the dried okra sample as affected by drying method were investigated. Drying curves showed that the application of ultrasound and infrared could increase the drying rate. In terms of quality parameters, UIACHD performed significantly better than oven drying and the quality of the products was comparable to freeze-drying. Flow and oscillation rheology tests showed that UIACHD drying could result in okra hydrocolloids with higher apparent viscosity and the application of ultrasound and infrared has preserved the rheological properties of the okra hydrocolloids. The microstructure of the dried okra slices was also well preserved by UIACHD. This study showed that UIACHD is a suitable drying method for maintaining the physicochemical quality of dried okra.Industrial relevanceDried okra can be used as a nutritious and functional ingredient in the formulation of different products such as soups, sauces and other culinary products. This study shows that ultrasound and infrared assisted conductive hydro-drying can be a suitable method for the production of high quality dried okra with well-retained color, nutritional value and rheological properties.     

Comparison of crystallized coconut sugar produced by traditional method and amorphous coconut sugar formed by two drying methods: vacuum drying and spray drying

Coconut sugar is traditionally produced by evaporating sap until reaching its saturated liquid and formed a crystalline structure. This study investigated the comparison of coconut sugar made by traditional method (crystalline structure) and dried coconut sugar (predominantly amorphous structure) to its characteristics. Two different formulation of coconut sap : maltodextrin (7 : 3) and (6 : 4) (weight/weight) were dried using vacuum oven (70℃, 6 hours) and spray dried (Tinlet 120℃.) Coconut sugar was characterized for moisture content, crystallinity, water sorption isotherm, hygroscopic rate, color, dissolving time, and powder recovery. Initial moisture content was examined and in range of 1.33% - 3.44% (wb). The highest monolayer water content was obtained by using spray drying (6 : 4) and lowest was obtained by traditional method. X-ray diffraction showed that dried coconut sugar powder had dominant amorphous structure (70.9 – 71.4%) while traditional one was dominated with crystalline structure (90.5%). Traditional coconut sugar was the least hygroscopic (1.21 × 10-4 g water/g solid/minutes), followed by vacuum dried coconut sugar (1.48 × 10-4 g water/g solid/minutes) and spray dried ones (1.56 – 1.67 × 10-4 g water/g solid/minutes). Spray dried coconut sugar had the brightest and the whitest color, followed by vacuum dried and traditional coconut sugar. Vacuum dried powder was quicker to dissolve (13.33 – 16.67 s), while increasing maltodextrin in spray drying could not decrease the dissolving time. The highest powder recovery of dried sugar was obtained by using vacuum drying and higher maltodextrin concentration (88.70%) while traditional method produced 100% powder recovery.     

微波干燥对芝麻品质特性的影响

研究微波干燥温度和干燥时间对芝麻的水分含量、发芽率及其油脂的酸价和过氧化值的影响,并利用固相微萃取-气质联用仪对处理后芝麻的挥发性成分进行了研究。结果表明:在低于90℃温度下干燥的前20 min内,芝麻含水量下降迅速,超过20 min后随着时间的延长,芝麻的水分散失速度逐渐变慢;微波干燥对芝麻的发芽率有破坏作用。干燥的前20 min内,温度低于80℃时,干燥温度升高对芝麻油酸值和过氧化值的影响不显著（p>0.05）,而温度高于80℃时,其对芝麻油酸值和过氧化值有显著影响（p<0.05）;随着干燥温度升高,干燥芝麻的主要挥发性成分烷烃类、萘类、酚类成分含量降低,醛类含量升高。      

不同干燥方法对葛根黄酮含量的影响研究

目的:研究不同干燥方法对葛根总黄酮及葛根素、大豆苷、大豆素、染料木苷、染料木素含量的影响。方法:采用分光光度法和高效液相色谱法测定热风干燥、真空干燥、冷冻干燥法干制葛根粉中葛根总黄酮、葛根素、大豆苷、大豆素、染料木苷、染料木素含量,研究干燥方法对葛根黄酮含量变化的影响规律,探寻最佳葛根干燥方法。结果:冷冻干燥葛根总黄酮含量最高,热风干燥葛根总黄酮含量最低,冷冻干燥、真空干燥和低温热风干燥葛根总黄酮含量无显著差异;热风干燥中,随着干燥温度升高,葛根总黄酮、葛根素、染料木苷、大豆素含量降低,染料木素损失殆尽,大豆苷含量增加;冷冻干燥、真空干燥对葛根素、大豆苷、染料木素含量影响差异显著,对大豆素、染料木苷含量影响差异不显著。结论:葛根干燥时,考虑干燥成本宜采用低温热风干燥;考虑葛根内在品质宜采用真空干燥,冷冻干燥对葛根内在品质提高有限。      

超声处理对中短波红外干燥红枣时间及品质的影响

为提高红枣干燥品质,减少干燥时间,以干燥时间为响应值,响应面优化得到红枣中短波红外干燥前超声处理条件为：频率40 kHz、时间40 min、功率350 W。最优超声处理后中短波红外干燥红枣至其干基含水率约为40%时所需干燥时间为9.55 h;未超声处理中短波红外干燥需13.33 h;传统热风干燥需17.13 h。扫描电镜观察红枣果皮,超声处理40 min使果皮表面产生大量裂缝,表皮层变薄,仅38.8 μm,表皮层和亚表皮层易分离,利于干燥过程中水分扩散,显著缩短中短波红外干燥时间。红枣超声处理后中短波红外干燥的干制品品质显著优于未超声处理红外干燥,极显著优于传统热风干燥。最优超声处理条件结合中短波红外干燥,所得干制品在3 种处理方式中总VC、总酚、总黄酮含量最高,糖酸比最高,色泽最优,能耗最少,是适合红枣干燥的技术方法。