Effect of ultrasonic power on drying process and quality properties of far-infrared radiation drying on potato slices

Food Science and Biotechnology - The experiments of contact ultrasound-assisted far-infrared radiation (FIR) drying on potato slices were conducted to investigate the effects of ultrasonic power on...     

Ultrasound as pretreatment for drying garlic slices in microwave and convective dryer

Food Science and Biotechnology - The effects of ultrasound pretreatment (US) before hot air drying (HAD) and microwave drying (MWD) of garlic slices were investigated. For this aim ultrasonic bath...     

Influence of process variables on the drying of potato slices

Investigation of the effects of varying air velocity, slice thickness, and pre-treatment with sodium chloride solutions and surface active agents on drying potato slices indicated that the drying occurred entirely in the falling rate period and was controlled by the mechanism of liquid diffusion. The rate of drying, and therefore the diffusion coefficients, increased with the addition of sodium chloride and surface active agents. Diffusion coefficients were also influenced by air velocity and slice thickness, suggesting that the rate of drying of potato slices is controlled by a combination of internal and external resistances.     

超声预处理对真空冷冻干燥猕猴桃片品质的改善作用

目的 以“海沃德”猕猴桃为原料,采用超声预处理改善真空冷冻干燥猕猴桃片的品质。方法 分别采用不同功率（60 W,120 W,180 W,240 W,300 W）和时间（1 min,5 min,10 min,15 min,20 min）的超声波预处理猕猴桃,经真空冷冻干燥制成真空冷冻干燥猕猴桃片,分析真空冷冻干燥果片的水分含量、可溶性糖、可滴定酸、维生素C含量、水分活度、色度等指标,探讨超声预处理对真空冷冻干燥果片品质的影响规律。结果 超声功率为60 W~180 W时,真空冷冻干燥猕猴桃片的含水量提高2.51%~13.70%;超声时间为1 min~10 min时,含水量提高9.23%~11.75%。与空白相比,所有超声组的可溶性糖含量、可滴定酸含量、糖酸比均略有提高,但维生素C含量平均下降9.66%。超声预处理显著降低真空冷冻干燥猕猴桃片的水分活度,60 W~300 W超声组的水分活度下降4.29% ~20.86%;1 min~20 min超声组的真空冷冻干燥猕猴桃片水分活度下降4.91%~15.34%。所有超声组的a*值均下降,显著低于空白,其中300 W超声波使a*值下降25.08%,超声冻干果片颜色更绿。结论 猕猴桃在真空冷冻干燥加工之前,使用功率120 W ~240 W和时间1 min ~5 min超声波进行预处理,有助于改善真空冷冻干燥猕猴桃片的整体品质。     

超声预处理哈密瓜片红外干燥工艺优化

目的:优化哈密瓜片红外干燥工艺,提质增效。方法:利用超声处理作为预处理方式,研究干燥温度、切片厚度和超声处理时间对干燥时间、色差值、维生素C含量的影响,并对其产品与未经超声处理产品的干燥时间、品质和微观结构进行对比分析。结果:超声预处理哈密瓜片红外干燥的最佳工艺参数为干燥温度61℃、切片厚度6 mm、超声处理时间15 min,此条件下干燥时间为115 min、色差值为13.79、维生素C含量为112.1 mg/100 g。相较于未经处理的产品,干燥时间缩短了45.24%,色差减小了13.38%,维生素C含量提高了16.71%。微观结构显示超声波引起哈密瓜片内部组织膨胀和收缩,呈多孔道结构。结论:超声处理可作为改善哈密瓜片红外干燥的预处理方式,实现干燥过程的提质增效。     

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。     

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.     

果蔬微波真空干燥（MVD）技术研究进展

为了提高甘薯干燥效率和改善产品品质,本文采用微波真空干燥（MVD）技术,研究了超声处理（US）、渗透脱水（OD）、超声辅助渗透（USOD）、真空辅助渗透（VAOD）和超声/真空辅助渗透（VUOD）对甘薯切片干燥动力学、微观结构、孔隙特征及理化性质的影响。采用Weibull分布函数和Dincer模型对干燥曲线进行拟合,并结合尺度参数（α）、形状参数（β）、滞后因子（G）、干燥系数（S）、毕渥数（Bi）探讨了MVD甘薯切片干燥过程的热、质传递机制。结果表明：相比其他处理,USOD和VUOD可显著提高甘薯切片的水分流失率（WL）和固形物增加率（SG）（P<0.05）。Weibull分布函数和Dincer模型对MVD甘薯切片的干燥曲线具有较好的拟合效果。模型参数（α, β, G, S）结果表明,经USOD处理的MVD甘薯切片干燥效率最高,加速阶段历时最短;毕渥数（Bi）处于0.243~3.617之间,表明MVD干燥过程甘薯切片温度变化由内部传导热阻和表面对流热阻共同控制。基于Weibull和Dincer模型计算获得的水分扩散系数D_cal和D_eff分别为7.986×10⁻⁸~1.249×10⁻⁷和1.508×10⁻⁸~8.272×10⁻⁸ m²/s,且均是USOD样品最大,OD最小。USOD和VUOD甘薯切片呈现蜂窝状、多孔结构,其中VUOD样品孔隙率最大（为33.30%）,而USOD样品平均孔径最小（仅为164.50 nm）、迂曲度最大（为41.97）。相比其它预处理,USOD和VUOD处理显著提升了MVD甘薯切片的复水性能（P<0.05）,降低了体收缩率,较好地保持了原有色泽,缩小了色差。研究结果可为甘薯切片的微波真空干燥条件筛选和品质调控提供参考。     

枣片的预处理及干燥方式研究

以木枣为实验材料,探讨不同的脱水预处理和干燥方式对枣片品质的影响。采用真空渗糖的方式对枣片进行脱水预处理,改变糖的种类和配比,对经预处理和干燥后的枣片进行综合评定,选择出一种较佳的糖液配方和干燥方式。研究结果表明,糖液的最佳配比为25%蔗糖、35%葡萄糖,产品的综合得分高达96.87。采用真空低温方法干燥枣片,所得产品品质较佳、加工时间短。     

不同预处理方法对马铃薯片热泵干燥速率及其干片品质的影响

采用烫漂、汽蒸、冷冻、汽蒸+冷冻和烫漂+冷冻5种方法对马铃薯片进行预处理,比较其热泵干燥速率及干片复水比,并使用测色仪、物性分析仪、凯氏定氮法和扫描电镜分别测定干片的色泽、质构、蛋白质含量和微观结构。结果表明,汽蒸预处理效果最好,即在一定条件下,干燥2 h后干片的水分含量达到14. 80%,比对照组干燥时间缩短了25. 9%; L~*值(亮度)和b~*值(黄度)分别为87. 44和31. 77;硬度居中(1 546. 35 g),脆度较小(17. 24 mm);复水比(4. 65)和蛋白质含量(9. 90%)均最高;且干片表面呈"结壳硬化"的膜结构,内部呈"砖块堆砌"结构,干片平整无蜷曲,呈明亮的淡黄色,综合品质最佳。说明汽蒸预处理能显著提高马铃薯片的干燥速率,改善干片品质,适合推广应用。     

PEF as pretreatment to ultrasound-assisted convective drying: Influence on quality parameters of orange peel

Pulsed electric field (PEF) pretreatments and ultrasound (US) application are techniques previously used to enhance the drying operation, not only increasing the kinetics but improving product quality. Because PEF pretreatments could affect product structure and US influence depends on the internal structure of products, the combination of both techniques could have a synergistic effect. Thus, the influence of the combined application of pulsed electric field (PEF) pretreatments and ultrasound (US) during drying on the color, total phenolic content, ascorbic acid and antioxidant activity of orange peel was studied. To this end, a series of drying experiments (50 °C) was performed without and with ultrasound application (20.5 kW/m³) and with and without PEF pretreatments (1.20 kV/cm) for two different times, 200 μs (0.37 kJ/kg) and 600 μs (1.12 kJ/kg). Thus, when individually applied, ultrasound significantly shortened the drying time, and PEF pretreatments slightly extended the process. However, the shortest drying time was observed combining 200 μs PEF pretreatment and ultrasound. This combination also provided the more similar color parameter to the fresh samples and significantly increased the percentage of phenolic compound retention. In addition, every treatment with PEF exhibited a similar percentage of ascorbic acid retention, and only the longer pretreatment (600 μs) produced a reduction in the antioxidant activity retention. Therefore, the combined use of a PEF pretreatment and ultrasound application during orange peel drying can lead to an interesting way both to shorten the drying process and preserve important compounds.     

Experimental study on drying of pear slices in a convective dryer

The experiments were conducted on pear slices with thickness of 5 mm at temperatures of 50, 57, 64 and 71 °C with an air velocity of 2.0 m s^?1. Prior to drying, pear slices were pretreated with citric acid solution (0.5% w/w, 1 min, 20 °C) or blanched in hot water (1 min, 85 °C). Also, the untreated samples were dried as control. The shortest drying time of pear slices was obtained with pretreatment with citric acid solution. It was observed that whole drying process of pear slices took place in a falling rate period. Four mathematical models were tested to fit drying data of pear slices. According to the statistical criteria (R², χ² and RMSE), the Midilli et al. model was found to be the best model to describe the drying behaviour of pear slices. The effective diffusivity of moisture transfer during drying process varied between 8.56 × 10^?11 and 2.25 × 10^?10 m² s^?1, while the activation energy of moisture diffusion in pear slices was found to be 34.95–41.00 kJ mol^?1.     

前处理和干燥对马铃薯全粉品质影响的研究进展

马铃薯全粉是新鲜马铃薯经去皮、切片、漂烫、护色等后脱水干燥制成的片状或粉末状产品,包含了除薯皮以外大部分马铃薯的营养物质,因此马铃薯全粉具有营养丰富、耐储的优点。作为马铃薯主粮化的原料,马铃薯全粉有助于改善和丰富我国居民膳食营养结构。近两年对马铃薯全粉的研究较多地集中在添加了马铃薯全粉制成的主食类或者其他相关产品的开发上。马铃薯全粉品质除了与马铃薯品种有关外还受到马铃薯全粉加工工艺的影响。本文将从马铃薯全粉生产过程中的前处理和干燥两个方面对马铃薯全粉品质的影响进行综述,以期为该领域的研究者提供理论参考。     

Modelling of air drying of fresh and blanched sweet potato slices

Effects of blanching, drying temperatures (50–80 °C) and thickness (5, 10 and 15 mm) on drying characteristics of sweet potato slices were investigated. Lewis, Henderson and Pabis, Modified Page and Page models were tested with the drying patterns. Page and Modified Page models best described the drying curves. Moisture ratio vs. drying time profiles of the models showed high correlation coefficient (R² = 0.9864–0.9967), and low root mean squared error (RMSE = 0.0018–0.0130) and chi‐squared (χ² = 3.446 × 10^–6–1.03 × 10^–2). Drying of sweet potato was predominantly in the falling rate period. The temperature dependence of the diffusion coefficient (D_eff) was described by Arrhenius relationship. D_eff increased with increasing thickness and air temperature. D_eff of fresh and blanched sweet potato slices varied between 6.36 × 10^–11–1.78 × 10^–9 and 1.25 × 10^–10–9.75 × 10^–9 m² s^–1, respectively. Activation energy for moisture diffusion of the slices ranged between 11.1 and 30.4 kJ mol^–1.