春笋微波干燥色泽模型及工艺试验

通过讨论春笋在微波干燥过程中水分含量和颜色的变化规律，建立了相应的动力学变化模型，用于微波干燥中品质变化的预测与监控。并以前期发射功率、后期发射功率和转换时水分含量作为因素，以单位失水率、复原率、色泽参数L、a和b为指标，设计三因素三水平正交试验，得出较佳的工艺组合。     

微波干燥刀豆的特性及工艺研究

进行了微波干燥刀豆试验，得到物料降水特性和温度特性。恒速和降速期的速率模型分别为ａｅ￣ｂＧ，ａｅ￣ｂｇ·Ｍ。以干燥前期质量比功率、后期质量比功率、前期干燥时间和装载量作为因素进行正交干燥试验，分别获得对外观质量、降水率、单位能耗和复水比等四项指标的影响规律及较佳工艺参数组合。     

春笋微波干燥色泽模型及工艺试验

通过讨论春笋在微波干燥过程中水分含量和颜色的变化规律 ,建立了相应的动力学变化模型 ,用于微波干燥中品质变化的预测与监控。并以前期发射功率、后期发射功率和转换时水分含量作为因素 ,以单位失水率、复原率、色泽参数L、a和b为指标 ,设计三因素三水平正交试验 ,得出较佳的工艺组合。     

真空微波与热风联合干燥蒜片的工艺研究

运用正交实验对四种无硫护色液进行复合实验,最佳护色组合为：CaCl2浓度为0.6%、NaCl浓度为0.8%、L-半胱氨酸浓度为0.10%,经此复合护色液护色得到干燥蒜片L＊值为86.23。比较了热风、真空微波、真空微波与热风联合干燥三种生产工艺所得蒜片干制产品的品质,采用正交实验优化了热风与真空微波联合干燥蒜片的生产工艺。结果表明：前期采用真空度-90kPa,微波功率375W,微波干燥20min,后期60℃热风干燥60min,干燥总时间为80min,缩短了热风干燥时间,得到了高品质的蒜片产品。     

冷泡红茶微波干燥工艺的优化研究

冷泡红茶是一款具有便捷、健康特点的新兴品种茶叶。为探讨冷泡红茶微波干燥最优工艺,通过单因素实验研究冷泡红茶微波干燥工艺中不同的微波功率、铺盘厚度和干燥时间对茶叶品质的影响,以水浸出物含量、感官得分为综合评判指标,得到较合适的微波工艺参数为微波功率12000W、铺盘厚度1.5cm、干燥时间8min。在此基础上,通过三因素三水平的正交试验优化,结果显示干燥时间、微波功率分别是影响冷泡红茶水浸出物含量、感官得分的最主要因素;冷泡红茶最优微波干燥工艺为微波功率12000W、铺盘厚度2.0cm、干燥时间10min,此时冷泡红茶水浸出物含量为31.4%,感官得分为96分、水分含量为6.3%,符合标准GB/T13738.2-2017中小叶种功夫红茶的要求。     

莴苣微波喷动均匀干燥工艺

通过单因素实验和正交实验确定莴苣微波喷动干燥的最佳工艺参数,并将产品和热风、喷动、真空冷冻、真空微波干燥的产品进行比较,旨在发现微波喷动干燥的优势所在。产品的质量主要通过复水率、叶绿素质量分数、色泽、能耗、感官评定等方面来衡量。实验结果表明,莴苣最佳微波喷动干燥参数为干燥前期(10min),微波功率为300W,热风温度为68～78℃,喷动风速为8m/s;干燥后期(45min)微波功率为200W,热风温度为68～78℃,喷动风速为6m/s。检测结果表明,微波喷动干燥产品的复水性、叶绿素质量分数、色差值和感官评定均优于热风干燥、喷动干燥和真空微波干燥产品,复水性和叶绿素质量分数略低于真空冷冻干燥产品,微波喷动干燥在节约能耗方面有显著效果。     

菠萝片微波真空干燥特性及工艺参数优化

通过单因素试验及三因素二次回归正交试验,研究了微波功率、干燥室压力、物料厚度对菠萝片干燥特性和菠萝片干制品可溶性糖、可滴定酸和抗坏血酸保存率及单位耗电量的影响,建立了各指标与试验因素间的回归数学模型,并利用多目标非线性优化方法,确定了菠萝片微波真空干燥最优工艺参数,即微波功率为1.4 W/g、片厚度为4.06 mm、干燥室压力为60.9 Pa.     

桃脆片的微波真空干燥工艺研究

为提高果蔬干制产品质量,降低干燥能耗,通过单因素及正交实验,研究了微波功率、干燥时间、物料厚度对桃脆片干燥特性的影响,确定了桃片微波真空干燥的最佳工艺条件,并将热风干燥桃片和微波真空干燥桃片在产品外观、营养成分、质构方面进行比较,结果表明:最佳工艺条件为微波功率600W,切片厚度3mm,干燥时间120min。微波真空干燥更适合于桃脆片产品的干燥,其产品的各项物理、化学性质均优于热风干燥产品。     

玉米热风与微波联合干燥工艺优化研究

对玉米进行热风与微波联合干燥实验研究,目的是缩短单独热风干燥玉米时间,节约能耗,同时利用微波干燥对环境无污染的优势。通过单因素试验和正交试验优化设计,得到玉米联合干燥的较佳工艺条件。结果表明联合干燥玉米的较佳工艺条件为:转换水分点为20%,微波功率为119 W,微波时间为8 min。此条件下干燥玉米,其裂纹率为0%,颜色和气味基本正常。     

葛根微波干燥中的护色工艺研究

利用微波干燥的高效、均匀性对葛根进行快速干燥.针对葛根微波干燥过程中易出现褐变现象,影响产品感官品质,本文特对葛根微波干燥加工中的护色工艺进行探究.在干制前,采用经济和无残留的氯化钠、柠檬酸、氯化钙复合护色液对切分成型的半成品进行预处理后,再经清水漂洗、离心脱水后,然后进行微波干燥,可使干制品维持其原有组织的洁白色泽.试验前期,先通过单因素试验对氯化钠浓度、柠檬酸浓度、氯化钙浓度、前期加热功率与装载量比值、前期加热时间五个因素进行初步探索,甄选出护色效果显著的各因素最佳水平范围.最后再通过正交试验筛选出最佳值,即:氯化钠浓度1.0%、柠檬酸浓度1.00%、氯化钙浓度0.60%、前期加热功率与装载量比值(W/g)为2、前期加热时间为8min.     

土豆片的微波干燥特性及较佳工艺研究

进行了微波干燥土豆片的正交试验,得出微波干制土豆片失水特性及耗电特性;进行了回归分析,获得了微波干燥土豆方程,采用Page方程拟合较佳。进行了3因素4指标的二次正交回归试验,得出各指标的回归方程、3因素对4指标影响的显著性,并进行参数综合优化,提出了参数的较佳组合。     

响应曲面法漂白紫胶真空干燥条件的优化

为得到漂白紫胶真空干燥的优化条件,研究了不同温度和压强条件下漂白紫胶产品的颜色指数和干燥时间,用响应曲面法(RSM)设计试验并建立了真空干燥方法的拟合方程。结果表明,预测值和实测值的一致性较好,所建立的数学模型可以用于描述漂白紫胶的真空干燥。通过优化得到了漂白紫胶真空干燥的最优条件：温度30℃,压强30kPa,可以得到颜色指数为1.0 的漂白紫胶,其指标符合国家精制漂白紫胶1 级标准;温度50℃,压强30kPa,可以得到颜色指数为1.4 的漂白紫胶,其指标符合国家精制漂白紫胶2 级标准。同时对此条件进行了验证,结果表明这两种条件下制得的漂白紫胶符合国家标准,可以为生产提供参考。     

不同前处理方式对沙枣叶总黄酮提取的影响

取沙枣叶采用超声波法提取总黄酮,紫外-可见分光光度法测定含量。分别对干燥方法,烘干温度,破碎度对其总黄酮得率的影响进行研究,同时考察了不同生长期沙枣叶中总黄酮含量变化。结果表明,冻干法处理后提取沙枣叶总黄酮得率最高,达到1.62%;其次为烘干法,最佳烘干温度为80℃,最佳破碎度为60目,此条件下总黄酮得率为1.57%;5月~9月生长期间,9月摘取沙枣叶最为适宜,测定总黄酮含量为1.78%。     

胡萝卜薄片热风与热泵结合干燥工艺及特性研究

研究了热风与热泵结合干燥胡萝卜的显微结构和化学变化特征 ;采用均匀设计方法进行胡萝卜结合干燥工艺参数试验 ,以平均干燥速率、胡萝卜素含量、复水比和彩度为指标 ,求解了单目标和多目标最优工艺参数。     

Colour,phenolic content and antioxidant capacity of some fruits dehydrated by a combination of different methods

The objective of this study was to improve product quality of dehydrated fruits (apple, pear, papaya, mango) using combined drying techniques. This involved investigation of bioactivity, colour, and sensory assessment on colour of the dried products as well as the retention of the bio-active ingredients. The attributes of quality were compared in regard to the quality of dehydrated samples obtained from continuous heat pump (HP) drying technique. It was found that for apple, pear and mango the total colour change (ΔE) of samples dried using continuous heat pump (HP) or heat pump vacuum-microwave (HP/VM) methods was lower than of samples dried by other combined methods. However, for papaya, the lowest colour change exhibited by samples dried using hot air–cold air (HHC) method and the highest colour change was found for heat pump (HP) dehydrated samples. Sensory evaluation revealed that dehydrated pear with higher total colour change (ΔE) is more desirable because of its golden yellow appearance. In most cases the highest phenol content was found from fruits dried by HP/VM method. Judging from the quality findings on two important areas namely colour and bioactivity, it was found that combined drying method consisted of HP pre-drying followed by VM finish drying gave the best results for most dehydrated fruits studied in this work as the fruits contain first group of polyphenol compounds, which preferably requires low temperature followed by rapid drying strategy.     

双孢蘑菇的冷冻干燥与高真空干燥

用冷冻干燥法和高真空干燥法分别对双孢蘑菇进行干燥,所得干制品在感官质量和复水性上无明显差别,但是,制品达到相同水分含量所需的干燥时间却有较大差别,高真空干燥法所需时间较短．实验证明,高真空干燥法非常适宜于多孔多纤维类物料（如蔬菜类产品）的干燥,并可在质量不受影响的前提下提高干燥效率．     

甘蓝的新型组合干燥工艺

为了克服单一干燥造成的品质缺陷,提出了一种新型的组合干燥方式,以改善产品的外观品质和复水特性。以甘蓝为研究对象,主要探讨了组合干燥过程中热风温度、干燥转换点的物料含水率、微波强度、渗透处理对干燥特性的影响;并以成品色泽、复水比、Vc保留率为指标,对不同干燥方式获得的产品性能进行了比较。研究获得的组合干燥工艺参数为:70℃热风干燥至物料含水率60%,2.5 W/g微波强度下干燥至40%含水率,25℃下以2.8 g/mL料液比向半干产品中加入28%葡萄糖和15%NaCl混合渗透液处理15 min,最后70℃二次热风干燥至成品。产品的水分活度为0.466,含水量为16.34%,复水比为8.71,Vc保留率为31.05%。结果显示,组合干燥方式干燥速率快,能耗低,产品含有高水分含量、低水分活度,产品品质与真空冷冻干燥的产品相近,是一种工业化生产果蔬干制品的新方法。     

CONVECTIVE DRYING OF PUMPKIN: INFLUENCE OF PRETREATMENT AND DRYING TEMPERATURE

The aim of this research was to study the influence of blanching as a pretreatment on the drying rate, color and rehydration rate of pumpkin slices ( Cucurbita maxima ) dried in a convective dryer at 50, 60 and 70C.
The different pretreatments did not modify drying time. The diffusion coefficient depended on temperature and moisture content, but not on pretreatments. It varied between 1.6 and 2.9  ×  10⁻⁹ m²/s and activation energy was approximately 35.6 kJ/mol. The rehydration rate of the dried sample, which was found to be influenced by drying temperature but not by the pretreatments, reached about 2 kg water/kg dry solid in about 150 s in boiling water. Color parameters " L " and " b " were influenced by drying temperature and pretreatments. Parameter L varied between 36 and 53 and parameter b varied between 20 and 31. Samples dried at 70C without pretreatments presented color parameter values very similar to those of the fresh sample.

PRACTICAL APPLICATIONS

This work evaluates the pretreatment and drying conditions of pumpkin. Five parameters of the optimal product are considered: pretreatment time, drying time, temperature, color and rehydration rate of the product. With these results, drying of pumpkin can be carried out in industrial convective dryers and the dried product may be used in the preparation of soups, premixed foods, snacks, etc.     

Hydration of grain kernels and its effect on drying

Different hydration methods have been considered and their effect on the drying characteristics of corn and amaranth grains have been studied at different drying temperatures and the results compared with those for the fresh materials. The effect of hydration on drying was found to depend on the type of grain. In general, for corn hydrated grain particles the moisture content was found to be in a looser condition than it was in the fresh grains, and hence, smaller effective diffusion coefficients where found for the latter. Such differences were found to increase with increasing drying temperature. Also a first-order irreversible kinetic model was applied to the drying data for hydrated and fresh corn and a reduction on the drying activation energy was observed by the humidification process. In contrast, for the relatively small amaranth grains, both hydrated and fresh particles showed similar drying characteristics. The results suggest that drying kinetics and transport properties obtained for rehydrated grains can overestimate drying rates for the corresponding freshly harvested material, especially at relatively high moisture contents and for relatively large grain particles like corn.     

文蛤肉真空冷冻干燥时间影响因素的实验研究

探讨了在恒压条件下预冻温度、物料厚度和加热板温度对文蛤贝肉真空冷冻干燥时间的影响，通过正交实验得出了真空冷冻干燥时间影响因素的主次顺序。实验结果表明，不同的因素对文蛤贝肉真空冷冻干燥时间的影响是不同的，其中物料厚度的影响最大，而加热板温度影响较小。通过对某一操作备件下真空冷冻干燥时间理论预测值和实验结果的比较，验证了传质控制下冷冻干燥速率模型的应用，为本实验条件下文蛤贝肉真空冷冻干燥时间的计算提供参考。