木材干燥特性及干燥工艺研究方法探讨

介绍了测定不同树种木材干缩特性和干燥特性、拟订干燥基准及选择干燥工艺的方法,为研究制定木材干燥工艺提供了一套较完整的方案.     

木材过热蒸汽干燥技术发展

阐述了过热蒸汽干燥技术研究现状以及干燥特性,并且对木材过热蒸汽干燥和常规干燥进行了对比,最后对木材过热蒸汽干燥技术提出一些建议。     

大葱热风微波真空组合干燥试验

对大葱进行了微波真空干燥试验,分析了大葱切段长度、微波功率对大葱微波真空干燥效果的影响,对热风微波真空组合干燥、热风微波组合干燥、微波真空干燥和热风干燥4种干燥方式对大葱干燥效果的影响进行了比较。大葱切段长度对热风微波真空组合干燥的干燥时间和感官品质有显著影响,随着微波功率增大,大葱的干燥时间缩短,感官质量下降;热风微波真空组合干燥的大葱切段长度为5mm,先采用热风干燥温度60℃烘干2.5 h后,在真空度0.085MPa和微波功率0.65kW的条件下,再进行微波真空干燥18min,其整个干燥时间为2.8h,比热风干燥缩短了1.7h。热风微波真空组合干燥的干制品的感官状态比热风干燥差,比热风微波组合干燥和微波真空干燥好,干燥时间与热风微波组合干燥接近,比微波真空干燥延长了2.2h,时间增加了3.6倍。     

花生荚果干燥技术及设备的研究现状与发展

花生作为世界重要的油料之一,在农作物中占据举足轻重的地位.刚收获的新鲜花生荚果由于水分较高易受到多种因素影响而导致霉变并产生黄曲霉毒素,从而影响使用安全并降低花生的经济价值.花生荚果收获后及时干燥可有效抑制微生物和霉菌的生长及繁殖,降低环境温湿度对花生储藏的影响,更大限度的保证花生的品质和使用安全.归纳了国内外花生荚果...     

胡萝卜热泵-远红外联合干燥工艺研究

采用热泵-远红外联合干燥工艺对胡萝卜片进行了干燥试验,研究了胡萝卜干燥预处理工艺、热泵干燥温度、远红外线辐射强度及联合干燥时间切换点对干燥速度、干燥能耗和类胡萝卜素损失率的影响。确定了胡萝卜热泵与远红外线联合干燥工艺的最佳工艺参数为:物料热烫时间120s,热泵干燥温度45℃,远红外热源辐射功率为2kW,热泵干燥与远红外切换点为物料含水率为50%。     

不同干燥方式对颗粒状果蔬品质变化的影响

分别对真空微波干燥、冷冻干燥、热风干燥及热风与真空微波联合干燥等不同干燥方式对颗粒状果蔬质量变化的影响进行了讨论，以VC和叶绿素的保持、色泽的差异、收缩和复水性能等为质量参数，分别进行比较。真空微波干燥在以上各质量参数方面，虽比冻干产品有一定差距，但远优于常规热风干燥。采用常规热风与真空微波联合干燥方式也能较好地改善颗粒状果蔬的品质。     

真空冻干和热风烘干海蓬子干品品质的比较

为了比较研究真空冷冻干燥海蓬子干品和热风干燥海蓬子干品的品质,通过两者的感官、复水性、营养成分和卫生指标等方面进行了比较。结果表明,真空冷冻干燥海蓬子干品的感官接近新鲜海蓬子,热风干燥海蓬子外观品质差;前者经95℃热水浸泡2min基本恢复鲜品状态,而后者相反;前者营养成分远高于后者;两者均符合食品卫生标准,前者产品技术指标符合NY/T1045-2006(绿色食品脱水蔬菜)质量安全要求。     

优质稻谷保鲜干燥方法研究

将水分为16.0%～18.6%的新收割优质稻谷采用包装打围、中间散存的方式储藏,分别使用热风就仓干燥,自然风就仓干燥和低温储藏干燥等方法进行干燥处理,同时也使用低温烘干机和自然晾晒等方法进行干燥处理。结果表明:各种干燥处理都达到了满意的效果,达到预期干燥水分,干燥均匀,未增加裂纹粒(爆腰粒),发芽率、黄粒米率、整精米率、脂肪酯值和粘度等重要品质指标未发生明显变化,品质新鲜。通过试验找到了稻谷保鲜干燥方法,可与保鲜储藏稻谷的方法配套,为保鲜大米加工常年提供新鲜稻谷原料。     

Foam-mat drying technology: A review

This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods, and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method that allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40–90°C) at atmospheric pressure. Methyl cellulose (0.25–2%), egg white (3–20%), maltodextrin (0.5–05%), and gum Arabic (2–9%) are the commonly utilized additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous, and sticky products that cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying, and improved product quality it provides.     

干燥条件对熟化竹荪品质的影响

为了选出对熟化竹荪干制品最好的干燥方式及干燥温度,以熟化的竹荪为原料,比较热风干燥、真空干燥、远红外干燥和真空冷冻干燥4种干燥方式在不同的干燥温度条件下对熟化竹荪干制品色泽、复水性、质构、多糖含量及组织结构的影响。结果表明,真空冷冻干燥和真空干燥能使竹荪干制品分别在20,30min达到完全复水,而热风干燥和远红外干燥均需要40min才能完全复水。真空冷冻干燥和真空干燥的整体色泽#E值明显低于热风干燥和远红外干燥,其中真空冷冻干燥在20℃条件下干燥的竹荪干制品#E值最小为3.021。真空冷冻干燥和真空干燥均使竹荪干制品的硬度和咀嚼性小于热风干燥和远红外干燥,但对弹性影响不大。真空冷冻干燥能基本保持竹荪原有的组织结构且制品的多糖含量显著高于其他三种干燥方式。综合试验结果,真空冷冻干燥和真空干燥方式均能较好地保持熟化竹荪干制品品质。     

Microwave‐Osmotic/Microwave‐Vacuum Drying of Whole Cranberries: Comparison with Other Methods

A novel drying method for frozen‐thawed whole cranberries was developed by combining microwave osmotic dehydration under continuous flow medium spray (MWODS) conditions with microwave vacuum finish‐drying. A central composite rotatable design was used to vary temperature (33 to 67 °C), osmotic solution concentration (33 to 67 °B), contact time (5 to 55 min), and flow rate (2.1 to 4.1 L/min) in order to the determine the effects of MWODS input parameters on quality of the dried berry. Quality indices monitored included colorimetric and textural data in addition to anthocyanin retention and cellular structure. Overall it was found that the MWODS‐MWV process was able to produce dried cranberries with quality comparable to freeze dried samples in much shorter time. Additionally, cranberries dried via the novel process exhibited much higher quality than those dried via either vacuum or convective air drying in terms of color, anthocyanin content, and cellular structure.     

不同温度条件下玉米穗红外干燥试验研究

针对玉米收获后由于气候原因导致霉变发芽、公路晾晒造成严重污染,或采用“先脱粒后干燥”工艺导致籽粒破碎严重等问题,按照“玉米穗干燥→脱粒→玉米籽粒干燥”分段干燥工艺设计了一种玉米穗红外干燥试验台.试验结果表明,采用等温干燥时,较佳的干燥温度为58℃左右;采用变温干燥时,宜选用“先低后高”的变温方式,且在保证干玉米品质的前提下,应尽量选用较高的起始干燥温度;无论采用等温干燥还是变温干燥,其干燥温度均不得高于60℃.该玉米穗红外干燥试验台干燥均匀性好、设备的空间利用率高,解决了收获期玉米霉变或采用“先脱粒后干燥”工艺而导致的籽粒破碎率严重等问题,为玉米穗红外干燥机的研制提供了参考.     

核桃的变温滚筒催化红外-热风联合干燥研究

为了提高硬壳坚果类产品干燥效率,创新研制了一台新型多机组合式滚筒变温催化红外干燥设备,并采取变温滚筒催化红外-热风联合干燥技术,对核桃干燥效果、能耗和动力学过程进行了研究。研究表明,红外辐射温度、辐射距离和滚筒转速均对干燥效果有显著影响。在优选的最佳辐射温度300+400℃、辐射距离30 cm、滚筒转速25+35+35 Hz条件下催化红外预干燥22.50 min然后在温度43℃、风速3 m/s条件下热风干燥14 h,总干燥时长为14.38 h,与单一热风干燥(20 h)相比,干燥时长缩短了28.10%,且节约了25.04%的能耗,干制核桃表壳无褐斑,开壳率为0%,颜色指标L为54.24,a为10.61,b为19.89,呈较亮的红黄色。此外最大干燥速率0.28 g/(g·min)也显著高于单一热风的最大干燥速率0.11 g/(g·min)。相应的建立了用于预测其干燥过程中含水率以及干燥速率变化的Henderson-Pabis模型,R~2为0.99,RMSE为0.03,拟合效果良好。本研究得出变温滚筒催化红外-热风干燥是一种适宜硬壳坚果类产品干燥的新型高效节能方法。     

微波与热风组合干燥对板栗干燥特性的影响

为得到较好的爆壳脱衣效果、延长贮存时间,对板栗进行微波与热风组合干燥。本试验分析了微波干燥功率对板栗爆壳脱衣效果和熟化程度的影响以及热风干燥温度对板栗熟化程度和保存情况的影响。并得出了板栗的微波与热风组合干燥的优化参数。     

不同干燥方式对橄榄果粉品质的影响

比较微波干燥、热风干燥、真空干燥以及真空冷冻干燥对橄榄果粉外观色泽、物理特性、营养成分及微观结构等品质的影响。结果表明:真空冷冻干燥橄榄果粉色泽较佳,具有较高亮度和最低的红绿度,最接近鲜食橄榄绿色色泽;热风干燥和真空干燥所得果粉吸油性较低,吸湿性较高,热风干燥的果粉堆积密度和溶解度均最高,真空冷冻干燥的果粉堆积密度最低,吸湿率低,复水性、流动性、吸油性和溶解度均较高,微波干燥的果粉含水率最高,复水性、吸湿率、堆积密度、吸油性和溶解度均较低;微波干燥的还原糖、总酸含量损失较小,热风干燥的类黄酮损失较小,真空干燥的总糖和总酚含量损失较小,真空冷冻干燥的蛋白质含量损失较小。扫描电镜观察微观结构发现微波干燥和真空冷冻干燥果粉颗粒间空隙大,组织较光滑完整,皱缩少,热风干燥和真空干燥果粉颗粒间空隙小,部分皱缩。通过主成分分析品质综合得分结果为:真空冷冻干燥>真空干燥>热风干燥>微波干燥。     

莲藕脆片组合干燥工艺研究

为获得较优的莲藕脆片加工工艺,以莲藕为原料,探讨真空冷冻—热风组合干燥条件下,真空冷冻干燥时间、热风干燥温度、热风干燥时间三因素对组合干燥莲藕脆片品质的影响。结果表明,莲藕片组合干燥的最佳工艺参数为:真空冷冻干燥4h,50℃热风干燥2h。该条件制得的莲藕片,色差L*=77.65,a*=0.96,b*=9.03,硬度为385.3g。较热风干燥而言,真空冷冻—热风组合干燥可有效提高其品质。     

干燥工艺对苦瓜粉品质的影响

采用热风干燥、真空干燥、冷冻干燥和喷雾干燥工艺加工生产苦瓜粉,并就这4种工艺对苦瓜粉品质的影响进行了比较,以确定工艺生产时最佳的工艺和工艺参数     

微波真空组合干燥法制备脱水板栗片的研究

为缩短板栗脱水时间,提高产品质量,对新鲜板栗仁进行了微波和真空组合干燥试验。结果表明:先用微波高火干燥2min,再在80℃、0.076MPa条件下真空干燥45min,即可使产品含水量低于10%。微波真空复合干燥可以大大缩短干燥时间,而且产品质构疏松、色泽金黄。     

A comprehensive review of thin-layer drying models used in agricultural products

Drying is one of the widely used methods of grain, fruit, and vegetable preservation. The important aim of drying is to reduce the moisture content and thereby increase the lifetime of products by limiting enzymatic and oxidative degradation. In addition, by reducing the amount of water, drying reduces the crop losses, improves the quality of dried products, and facilitates its transportation, handling, and storage requirements. Drying is a process comprising simultaneous heat and mass transfer within the material, and between the surface of the material and the surrounding media. Many models have been used to describe the drying process for different agricultural products. These models are used to estimate drying time of several products under different drying conditions, and how to increase the drying process efficiency and also to generalize drying curves, for the design and operation of dryers. Several investigators have proposed numerous mathematical models for thin-layer drying of many agricultural products. This study gives a comprehensive review of more than 100 different semitheoretical and empirical thin-layer drying models used in agricultural products and evaluates the statistical criteria for the determination of appropriate model.     

真空冷冻与热风联合干燥草莓

应用真空冷冻干燥与热风干燥(FAD)联合的方式做不同转换点试验,将得到的产品分别与完全的热风干燥(AD)和真空冷冻干燥(FD)的产品比较总的能量消耗和物化特性,确定了 FAD联合干燥的方式和较佳转换点. FAD联合干燥的产品极大地改善了完全热风干燥草莓的品质,其质量较接近完全真空冷冻干燥的产品.