改进型前处理剂在冷轧堆前处理中的应用

在针织物冷轧堆前处理工艺中,通过改进型前处理剂与原来的冷来帮助剂在半成品质量、助剂成本等方面的对比,对改进型前处理剂做出评价。     

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。     

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。     

Influence of applied time and power of ultrasonic pretreatment on convective drying of potato slices

Food Science and Biotechnology - Ultrasound is a novel technology that can be applied as a pretreatment for the convective drying in order to reduce its undeniable shortcomings. The objectives of...     

预处理对红薯叶热泵干燥品质的影响

以红薯叶为原料,研究不同预处理(盐渍、超声以及二者联合)条件下红薯叶热泵干燥过程中理化性质的变化。结果表明:当盐浓度为4%时,干燥后的POD酶活性较低,抗氧化能力较强,该条件下获得的红薯叶复水比普遍较高,且干燥时间最短,综合评分最高。     

尿素在棉织物冷轧堆前处理中的应用

针对传统棉织物冷轧堆前处理中存在的碱和双氧水用量大、生产周期长、效率低的问题,研究了尿素在棉织物冷轧堆前处理中的应用.通过单因素及正交试验确定最佳工艺:H2O250 g/L,Na OH 45 g/L,尿素6 g/L,堆置时间11 h.该工艺条件下,织物白度80.2,强力806 N,毛效12.7 cm/30 min.     

微波干燥法生产南瓜粉的研究

对微波功率、处理时间、切片厚度等因素对南瓜粉的影响进行了研究,并将其对南瓜粉的影响进行了比较。研究结果表明,微波功率越强,失水速率越快,干燥所需时间越短;微波功率和微波处理时间的变化对南瓜Vc和胡萝卜素的破坏具有显著的影响,南瓜片厚度对南瓜Vc和胡萝卜素破坏的影响不显著。采用切片厚度3mm的南瓜片,功率640W、处理时间350s的微波干燥工艺获取的南瓜片,粉碎0.5min,过120目筛的微波干燥法生产南瓜粉生产工艺可以获得品质优良的南瓜粉。     

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。     

前处理和干燥对甘薯全粉品质影响的研究进展

本文从甘薯全粉生产过程中的前处理和干燥两个方面对甘薯全粉品质的影响进行综述,对现代食品技术在生产甘薯全粉中存在的问题进行了探讨,以期为该领域的研究者提供理论参考.     

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。     

Infrared thermography assisted control for apples microwave drying

A microwave based system was developed for drying of apple slices while on-line controlling their temperatures. An infrared thermography assisted control system allowed to realize temperature control by detecting the instantaneous maximum temperature among the samples under test instead of a chosen slice. The effectiveness of the system at hand in realizing temperature control both in space and in time was proven for three temperatures: 55, 65 and 75 °C. Temperature fluctuations became larger both with time increasing and with rising temperature levels thus causing a negative impact on dried fruit quality. In fact apples slices dried at 75 °C by microwave showed L^∗ (lightness) and white index (WI) values significantly lower (p < 0.05), when compared to the fresh samples and to the apples dried by hot air. To overcome such behaviour a mode stirrer was introduced resulting in halving the temperature spatial oscillations of sample slices.     

Osmotic dehydration of raspberries with vacuum pretreatment followed by microwave-vacuum drying

Defrozen raspberries were osmotically dehydrated in sucrose solution initially at low pressure (1.33 kPa for 8 min), and then at ambient pressure (4 h). Moisture decreased from 84% to 49% (wet basis), and almost one half of water removal occurred at the vacuum period. Two different transport coefficients were obtained: 19.9 × 10⁻¹⁰ m²/s for transport of water under vacuum, and 3.2 × 10⁻¹⁰ m²/s for water transport at atmospheric pressure. Losses of vitamin C were high (80%) and reutilization of sucrose solution is suggested. Osmotically dried raspberries were microwave-vacuum dried (1.33 kPa for 40 min) under on–off temperature control by varying microwave settings. An undamaged dried product (7.8% wet basis) of high quality (color, taste, structure) was obtained.     

Enhancement of anthocyanins extraction from haskap by cold plasma pretreatment

The economic value of haskap is low because of low utilization caused by factors such as harvesting, storage and transportation, and the sour taste. However, its value can be increased by extraction due to its large content of anthocyanins. This study helped to extract haskap by using cold plasma as pretreatment at different power (0, 100, 200, 300 W) in terms of extraction yield, monomer composition, and antioxidant capacity. It was shown that cold plasma pretreatment (CPP) degraded the cell wall components of haskap, increased its surface roughness, enhanced its hydrophilicity, improved its hydration properties, and modified its enzymatic activity. CPP significantly increased the extraction rate of anthocyanins (13.35‐20.47%), promoted the number of anthocyanin monomers, and enhanced the antioxidant activity of the extracts. These results suggest that CPP can successfully facilitate the extraction of anthocyanins and is a promising technology to add value to haskap for functional foods and nutritional products.Industrial relevance: Haskap is a good source of anthocyanins, however, conventional methods of anthocyanin extraction usually require the use of large amounts of organic solvents and are time-consuming. Cold plasma pretreatment can not only help reduce chemical pollution to the environment and improve the utilization of haskap, but also convert it into functional and nutritional food ingredients with value-added properties in a more efficient way.     

Improvement of water transport mechanisms during potato drying by applying ultrasound

BACKGROUND: The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms. RESULTS: Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m^?3), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P < 0.05) influence of the applied ultrasonic power on the identified kinetic parameters: effective moisture diffusivity and mass transfer coefficient. CONCLUSIONS: The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high‐quality dry products. Copyright © 2011 Society of Chemical Industry     

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。