香蕉片远红外干燥工艺的研究

香蕉片作为一种休闲食品具有较大的开发空间。试验以香蕉为材料,采用远红外干燥技术制作香蕉片。通过单因素试验考察护色剂浓度、烘干温度和烘干时间对香蕉片制作的影响。利用正交试验优化远红外干燥技术制作香蕉片的工艺条件。结果表明,远红外干燥法制作香蕉片的最优工艺条件为:护色剂浓度2%,烘干温度80℃,烘干时间5 h,在此条件下制得的香蕉片有较好的感官品质。试验为香蕉片远红外干燥技术的工业化应用提供理论依据。     

涂膜-超声复合预处理强化苹果片干燥特性及其品质提升

本文以苹果为原料,为提高热风干燥速率,改善产品品质,通过研究不同功率下（0、160、320、480 W）超声和羧甲基纤维素涂膜复合预处理对苹果片热风干燥特性（干基含水量和干燥速率）及产品品质（总酚、颜色、DPPH清除率、复水比、微观结构）的影响,为其它产品干燥提供研究依据。在60~90 ℃干燥条件下,苹果片的干燥速率、总酚含量、DPPH清除率、复水比均随着超声功率增大而增大,干燥时间、色差随超声功率增大而减少。在70 ℃、480 W条件下,可获得较高的干燥速率和较好的干燥品质,干燥时间为150 min,总酚含量为16.25 mg GAE/g DW,色差值ΔE为8.13,DPPH清除率为38.15%,复水比达5.23,用电子显微镜对苹果干制品进行观察微观结构,可以发现经超声处理后的干制品内部的褶皱多、微孔通道较多。综上,涂膜-超声复合预处理能够缩短干燥时间,提高干燥速率,提高产品的总酚含量、DPPH清除率和复水比,改善干制品色泽。     

铁棍山药超声强化热泵干燥的品质特性研究

为了探究铁棍山药超声强化热泵干燥的品质特性,对铁棍山药进行超声强化热泵干燥,研究干燥温度及超声功率对铁棍山药品质的影响,并结合权重分析确定最佳干燥条件。结果表明,干燥温度和超声功率对样品的脱水时间、微观结构、硬度值、复水比、ΔE值、多酚含量、多糖含量及IC₅₀值均有显著影响。在干燥温度65℃、超声功率60 W的条件下,样品的干燥时间最短(240 min)、硬度值最小(628.39 g),复水比最大(2.31 g/g),在干燥温度55℃、超声功率60 W的条件下,样品的多酚含量和多糖含量最大、ΔE值和IC₅₀值最小,分别为36.17μg/g、137.47μg/g、47.99和33.27μg/mL。基于变异系数法的权重分析表明,在干燥温度55℃和超声功率60 W条件下所得铁棍山药样品的综合评分最高,表明上述条件即为铁棍山药超声强化热泵干燥最优参数。研究成果可为超声强化热泵干燥技术研发与应用提供参考。     

超声和烫漂预处理对红薯叶热风干燥的影响

采用超声、烫漂两种方式对红薯叶进行热风干燥前的预处理,研究超声时间、超声功率、超声温度和烫漂时间、烫漂液ZnAc_2与EDTA-2Na质量比、烫漂温度对红薯叶热风干燥后叶绿素、复水性、色差、干燥特性、能耗以及微观结构的影响。结果表明:超声处理的最佳工艺为超声时间10min、超声功率300W、超声温度40℃,经超声预处理的红薯叶干燥效率较高,皱缩率低,组织结构较为完整;烫漂处理的最佳工艺为烫漂时间60s、烫漂液ZnAc_2与EDTA-2Na质量比2:1、烫漂温度80℃,经护色液烫漂处理干燥后的红薯叶复水率、叶绿素含量和色泽都稍高,质构紧密均匀,细胞开孔率高,总能耗低。     

热风与微波联合干燥香蕉片的工艺研究

应用热风-微波(AD + MD)联合干燥方式,通过L16(45)正交试验,探讨香蕉片联合干燥过程中热风温度、风速、干燥转换点的物料含水率、微波功率对干燥速率的影响;并以成品色差L值、复水率、VC含量、质构和复水率为指标,对联合干燥、热风干燥(AD)和真空冷冻干燥(FD)的产品进行比较.结果表明,热风-微波联合干燥方式的干燥速率快,能耗低,产品品质与真空冷冻干燥的产品相近;其最佳工艺条件为:先在热风温度65 ℃,风速2.4 m/s条件下干燥至物料的含水率为55%,再在微波功率为200 W条件下干燥至成品.     

微波-热风联用制取笋干工艺条件优化

为获得干燥时间短、干燥品质好的笋干,以竹笋为原料,在单因素试验的基础上,根据中心组合试验设计原理,分析微波干燥功率、微波干燥时间和热风干燥温度3 个因素对笋干感官评分、总干燥时间、复水比、色差和硬度指标的影响,以确定微波-热风联用制取笋干最佳工艺条件。结果表明,制取笋干的最佳工艺条件为：微波干燥功率6.3 W/g、微波干燥时间60 s、热风干燥温度65 ℃。在此条件下得到的笋干感官评分85.6、总干燥时间200 min、复水比6.17,干制品色差ΔE* 19.99、复水制品色差ΔE* 13.92、干制品硬度19 511.23 g、复水制品硬度20010.71 g,该工艺研究结果可为笋干产业化发展提供理论支持。     

节能型香蕉片热风干燥装置的设计与试验

结合热风干燥的特点,设计了一种节能型香蕉片热风干燥装置。以香蕉片为原料,进行热风干燥试验研究,主要分析香蕉片在不同热风干燥温度与不同切割厚度条件下含水率与复水率的变化规律,并结合感官评价得分得出香蕉片在该干燥设备试验过程中获得最优品质所需干燥温度与切割厚度。结果表明:热风温度越高,切割厚度越薄,干燥速率越快。获得最优品质所需最佳热风温度为60℃,最佳切片厚度为5 mm。     

热风干燥和远红外干燥对草莓粉品质特性的影响

采用热风干燥和远红外干燥分别在不同温度（60、70、80 ℃）处理草莓，并对6 种草莓粉中水分含量、维生素C含量、花青素含量、多酚含量、抗氧化活性、风味物质等品质特性进行测定分析。结果表明：热风干燥60 ℃和70 ℃时所得草莓粉水分含量较低，维生素C、花青素和多酚含量较高，其中热风干燥60 ℃时草莓粉DPPH 自由基清除率较高。草莓粉中的风味物质类型主要有醇类、醛类、酮类、酸类、酯类和烃类等，其相对含量在不同的干燥方式下随温度变化也不相同。6 种草莓粉经聚类分析，在欧氏距离为10 时，可分为3 类，第一类是热风干燥60 ℃，第二类是远红外干燥70 ℃，第三类是热风干燥70 ℃、热风干燥80 ℃、远红外干燥80 ℃和远红外干燥60 ℃。综上所述，热风干燥60 ℃时所得草莓粉品质特性较佳，在实际生产中可根据具体情况选择合适的干燥方式和干燥温度。     

热风-远红外联合干燥肉脯的工艺优化及其品质研究

为提高肉脯品质,本文研究了不同干燥技术对肉脯品质的影响,以水分含量、剪切力、色差和质构为指标,通过单因素和正交试验优化热风-远红外联合干燥肉脯的工艺条件,确定干燥模型,并对比分析微波、热风、远红外干燥技术对肉脯品质的影响。结果表明:热风-远红外联合干燥肉脯的最佳工艺为:第一段热风干燥温度Ⅰ170℃,第二段热风干燥温度Ⅱ 250℃,第三段红外烤制温度Ⅲ 260℃,干燥100 s,制得肉脯的水分含量低(13.54±0.48) g/100 g,嫩度高,易咀嚼,符合Modified Henderson and Pabis干燥模型(R2=0.9976);与微波干燥、热风干燥和远红外干燥相比,热风-远红外联合干燥的肉脯品质最佳,改善了产品的感官质量,水分含量、剪切力、硬度、咀嚼性、L*值和a*值分别是热风干燥的92%、55%、60%、46%、109%和121%,胶粘性和b*值无显著差异。该研究为肉脯的干燥加工提供了理论依据。     

红外干燥对树莓干燥特性、品质和抗氧化活性的影响

为了丰富树莓加工产品种类,提高树莓干燥效率和品质,研究不同红外干燥条件对树莓干燥特性和品质的影响。采用红外干燥法干燥树莓,探讨红外干燥温度和功率对树莓产品干燥特性、色泽、复水性、花青素保留率和抗氧化活性的影响。红外干燥温度对干燥速率影响显著,而功率影响不显著。随着红外干燥温度的升高,色泽相关参数如表征红色程度的a*值和色相h0值先升后降,色差E值先降后升,花青素保留率呈先增后降的趋势。在干燥温度70℃,功率675 W时,产品色泽保持最好,花青素的保留率较高(47.33%)。在设定的干燥温度范围,70~80℃产品复水比最大,抗氧化活性最强。干燥功率对树莓品质和抗氧化活性影响显著,低功率有利于产品色泽、复水性及花青素和抗氧化活性的保留。经综合评价,当红外干燥温度70℃,功率675 W时,树莓的色泽保持较好,复水比较高(1.54),花青素保留率较高(43.52%),抗氧化活性较强,ABTS和DPPH自由基清除能力分别为408.10μmol TE/100 mg DM和319.33μmol TE/100 mg DM,铁还原能力为540.18μmol TE/100 mg DM。     

Moisture transfer and microstructure change of banana slices during contact ultrasound strengthened far-infrared radiation drying

To explore water transfer and structure change during contact ultrasound strengthened far-infrared radiation drying (CU-FIRD) on banana slices, the effects of far-infrared radiation (FIR) temperature and contact ultrasound (CU) power on drying process, water transfer change, microstructure and pore evolution were studied. The results showed that the drying time could be shortened obviously by increasing FIR temperature and CU power. The effective moisture diffusivity values of banana slices were between 2.28 × 10⁻¹⁰–6.12 × 10⁻¹⁰ m²·s⁻¹, which increased with the rises of FIR temperature and CU power. The moisture changes in banana slices during CU-FIRD were analyzed by low-field nuclear magnetic resonance (LF-NMR). There were three kinds of water status in banana slices including bound water, immobilized water and free water. Free water was the main water in banana, and the increases of both FIR temperature and CU power could obviously shorten the removal time of free water. The immobilized water in banana slices increased first and then decreased during the drying process, and the improvements of FIR temperature and CU power could accelerate its mobility and migration. There was no significant change for bound water, which was the main water left in banana slices after drying. The SEM and shrinkage ratio results showed that higher FIR temperature and CU power could reduce the structure shrinkage of banana samples, increase the porosity, and generate more diffusion micro-channels with larger size, so as to speed up the migration process of water in banana. CU-FIRD could improve the porous structure of banana samples, enhance the heat and mass transfer process, and accelerate the migration and diffusion of water.     

Far-infrared radiation assisted drying of longan fruit

Oversupply of fresh longan (Dimocarpus longan Lour.) from seasonal production in Thailand needs to be preserved in the form of dried product (exported value of over US$70 million in 2009) to prevent it from being damaged by microorganism. Due to well known limitations of hot air (HA) drying, a new technique of using far-infrared radiation (FIR) in combination with hot air and heat pump (HP) dryers for longan is proposed in this study. Longan with initial moisture content of approximately 84–86% w.b. was dried to about 18% w.b. at the drying temperature of 55 °C in the case of combined FIR-heat pump drying and 65 °C in the case of combined FIR-hot air drying with 80% recycled air. In both cases, the electric power supplied to FIR rods was set at 250, 350 and 450 W. The experimental results are presented in terms of the drying kinetics, dried product qualities (color, shrinkage, percentage of rehydration, water activity, texture, and microstructure) and sensory characteristics of the dried product. The results show that FIR in combination with hot air and heat pump drying increases the drying rate of longan by reducing the drying time. FIR also helps to create more porous structure in dried longan, with porosity increasing with the power supplied to the FIR heaters. The formation of porous structure results in a product with lower shrinkage, improved rehydration, lower hardness and lower toughness than samples dried in the absence of FIR. In addition, the FIR dried longan had a stronger red color and appeared darker. Dried longans obtained by HP, HA, combined techniques and the product from the local market, were all rated similarly by a sensory panel for color, shape, flavor and taste. It is worth noting that the overall energy used for FIR-assisted drying processes decreased with the increase in the power supplied to the FIR heaters.     

Quality assessment of electrohydrodynamic and microwave dehydrated banana slices

In contrast to the inherently energy-efficient electrohydrodynamic (EHD) methods, conventional drying methods are energy intensive. In the present study, comparisons were made between banana slice samples dried by high-voltage-DC powered multiple-point-to-plate electrodes and those dried by microwave (MW). For this purpose, banana slices were dried by an EHD drying system at electric field strengths of 6, 8, and 10 kV/cm and by an MW drying system at specific power levels of 9 and 18 W/g. No constant rate period was observed in the EHD; hence, the entire drying process occurred in the falling rate period, whereas the drying rates of MW-dried samples occurred at a constant rate and during the falling rate periods. Analysis of variance showed that drying method had a significant effect on drying time, rehydration ability, shrinkage, color parameters (L^∗, a^∗, b^∗, and ΔE), and consumed energy. The mean values of specific consumed energy for EHD and MW drying methods were 0.34 and 9.66 kJ/g, respectively. In terms of drying time, EHD was not fast; however, its advantages of less energy requirement and great product quality including lower shrinkage, great rehydration ability, and better appearance make it a good choice for drying banana slices.     

Study of banana dehydration using sequential infrared radiation heating and freeze-drying

The drying and quality characteristics of banana slices processed with a sequential infrared radiation and freeze-drying (SIRFD) method were investigated. Cavendish bananas slices with 5 mm thickness were predehydrated using IR heating at each one of three radiation intensities, 3000, 4000, and 5000 W/m² or hot air at 62.8 °C. The predehydrated samples with 20% and 40% weight reductions obtained using 4000 W/m² IR intensity were then further dried using freeze-drying for various times to determine the effect of predehydration on the drying rate during freeze-drying. To improve the quality of dried banana chips, the banana slices were also treated with a dipping solution containing 10 g/l ascorbic acid and 10 g/l citric acid before the IR predehydration. Control samples were produced using regular freeze-drying without the predehydration. The quality characteristics of dried banana chips, including color, thickness shrinkage and crispness, were evaluated. The predehydration results showed that the drying rate of IR heating was significantly higher than the hot air drying and increased with the increase of IR intensity. For example, it took 10 and 38 min to achieve 40% weigh reduction by using IR at 4000 W/m² and hot air drying, respectively. However, the banana slices with IR predehydration dried slower during freeze-drying compared to the samples without predehydration, which was due to texture changes that occurred during the predehydration. Acid dipping improved product color and also reduced freeze-drying time compared to non-dipped samples. It has been concluded that SIRFD can be used for producing high crispy banana chips and additional acid dipping improved product color and reduced required freeze-drying time.     

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℃。     

热风、微波及其联合干燥对蒜片品质的影响

为研究热风、微波及其联合干燥对蒜片品质的影响,以大蒜片为原料,以干燥速率、硫代亚磺酸酯含量、感官评分、色泽L值、复水比和综合得分为指标,比较不同热风温度和微波功率对蒜片干燥特性和品质的影响,并以热风温度、转换点干基含水量、微波功率为实验因素,设计L₉(33)正交实验对热风微波联合干燥蒜片的工艺条件进行优化。结果表明:60 ℃热风干燥和550 W微波干燥所得蒜片干品的综合得分较高,分别为83.64和80.74分。热风温度和微波功率对联合干燥蒜片的综合得分影响极显著(p<0.01);转换点干基含水量对综合得分影响显著(p<0.05)。热风微波联合干燥蒜片的最佳工艺条件为前期热风65 ℃干燥至转换点干基含水量1.00 g/g,后期采用功率550 W微波干燥至干基含水量0.18 g/g。在此条件下,联合干燥制备脱水蒜片的干燥速率最快,硫代亚磺酸酯含量最高为1.7739 mmol/100 g,综合得分最高为92.21分,感官品质较好。因此,热风微波联合干燥技术是适合蒜片干燥的较好方法。     

Moisture diffusion by the fractional-time model in convective drying with ultrasound-ethanol pretreatment of banana slices

Innovative drying pretreatments play an essential role in preserving food and reducing drying energy consumption. The aim of this study was, therefore, to investigate the effect of drying pretreatments with ethanol (EH) and ultrasound (UA) on the drying kinetics and moisture diffusion through an anomalous solution by the fractional time, as well as to evaluate the physical, bioactive compounds and antioxidant properties of banana slices. The results indicated that Page's model analyzed the anomalous calculus approach for emerging drying techniques with the appropriate goodness of fit. The anomalous diffusivity approach described the experimental data well and provided new insights into the structure of food material. The new approach also showed that drying pretreatments promote convective drying, reduce drying time by up to 31% and save energy by 19%. Analytical results showed that banana slices pretreated with EH + UA had higher conservation of phenolic compounds and antioxidant activity, as well as an attractive color and high shrinkage. The findings could provide help in the large-scale processing of good-quality dried banana slices.     

响应面法优化香菇热风-微波联合干燥工艺

本文基于热风-微波分段联合干燥方式,探讨了联合干燥转换点干基含水率(2.00~5.00 g/g)、热风温度(50.0~70.0 ℃)及微波功率密度(6.67~33.33 W/g)对香菇营养成分、干燥特性及品质的影响。通过单因素实验确定较优参数范围并采用Box-Behnken组合设计优化联合干燥工艺,分析干燥工艺对干燥时间及香菇典型品质(色差、收缩率及多糖保留率)的影响。结果表明,通过响应面优化试验获得最优工艺为转换点干基含水率4.20 g/g、热风温度60.60 ℃、微波功率密度30.00 W/g,此条件下的联合干燥时间为178.33 min(其中热风干燥170 min,微波干燥8.33 min),产品色差ΔE为11.21,收缩率为65.28%,多糖保留率为66.98%,综合评分为0.145。研究结果表明热风-微波联合工艺能够实现对香菇的快速干燥,并保证较好的干品品质。