果蔬和水产品新型干燥预处理技术研究进展及未来展望

果蔬和水产品营养价值丰富,但含水率较高,极易引起微生物生长繁殖,进而导致腐败变质.干燥是延长果蔬和水产品货架期的有效途径,但干燥时间长、干制品品质差是限制该领域发展的瓶颈问题.采用热力或非热力预处理可有效提高干燥效率,改善干制品品质.基于此,本文综述了果蔬和水产品新型烫漂(高湿气体射流冲击烫漂、红外辐射烫漂、微波烫漂、...     

果蔬烫漂护色技术应用研究进展

烫漂护色是果蔬在干燥、油炸、冷冻及储存等加工处理前的一个重要的操作单元。烫漂的主要目的是钝化果蔬中引起不良变化反应的氧化酶,防止色泽劣变。烫漂方法主要包括化学法和物理法。化学试剂的残留对人的身体健康存在一定的威胁。传统的烫漂技术(热水及蒸汽烫漂)存在传热速度慢、营养损失大、水消耗量巨大、污水处理困难等缺点。因此,急需开展新的烫漂技术的研究。本研究对各种新型烫漂技术的原理、研究进展、应用现状和局限性等进行了分析和综述,主要包括微波、红外线、欧姆加热、射频、超高压等,以期为果蔬烫漂护色技术研究方向提供启示。     

魔芋片蒸汽漂烫灭酶最佳工艺参数研究

以鲜魔芋球茎为研究材料,在分析魔芋不同部位的多酚氧化酶活性的基础上,通过魔芋片厚度和漂烫时间2个单因素试验及其正交试验,探讨了最佳的蒸汽漂烫灭酶工艺参数。研究结果表明:用100℃饱和水蒸汽对3 mm~10 mm厚度的魔芋片漂烫5 min,,灭酶效果最好。本文研究结果可为工业化干燥无硫魔芋片提供有益参考。     

香蕉中多酚氧化酶的灭酶条件研究

比较了蒸汽、热水烫漂及微波灭酶的优劣,初步探讨了对香蕉进行微波灭酶的基本条件。结果表明,对于香蕉中的多酚氧化酶(PPO),微波灭酶较蒸汽及热水烫漂灭酶迅速,效果好;微波功率密度为4W/g时,5 min内将香蕉PPO活力降至5%以下,切片厚度对灭酶效果无显著影响,剥皮后可直接进行灭酶,单层或双层叠放。     

微波在刀豆脱水中的应用

本文利用微波技术对刀豆进行脱水处理，微波处理与热水烫漂相比具有维生素Ｃ损失少和灭酶彻底的优点，并且微波干燥比热风干燥的速率快时间短。     

输送带式真空-蒸汽脉动烫漂机的设计

果蔬真空-蒸汽脉动烫漂设备能够消除空气层热阻,提升烫漂均匀性。但此类设备为间歇式操作,存在劳动强度大、生产效率低、不能与生产线融合等问题。为此,设计一种输送带式真空-蒸汽脉动烫漂机。该机由烫漂箱体、蒸汽系统、真空系统、物料输送系统、密封系统等部分组成。研究对其关键部件进行设计、计算与选型;通过有限元分析软件对带加强筋的烫漂箱体进行静力学分析,箱体的强度和刚度满足设计要求;采用刀型闸阀对频繁启闭的物料进出口进行密封设计,对承压箱体内外传动的传动轴采用永磁联轴器进行密封。设计的输送带式真空-蒸汽脉动烫漂机能够提高工作效率,有助于促进真空-蒸汽脉动烫漂技术推广应用。     

射频加热技术及其在果蔬干制中的研究应用进展

干制是最重要的果蔬加工技术之一,选择合适的干制技术与干燥能耗、产品品质密切相关。射频加热技术作为一种新型物理加热技术,因其加热迅速、具有体积加热效应、能量穿透深度大等优点,同时兼具微生物控制和灭酶效果,近年来备受关注。本文主要综述了射频加热技术的作用机理及特点,影响其在果蔬干制加工中应用的因素,归纳总结了射频加热技术在果蔬干制、微生物控制与灭酶中的应用现状,探讨了射频加热均匀性问题及可能的解决方案,并对未来研究方向进行了展望,为其今后在果蔬干制工业化应用提供参考。     

真空—蒸汽脉动烫漂预处理对百合

将真空—蒸汽脉动烫漂预处理技术应用于百合的烫漂预处理,研究蒸汽烫漂时间、烫漂循环次数和真空度对百合烫漂后干燥特性、水分有效扩散系数、色泽和复水比的影响。结果表明：蒸汽烫漂时间、烫漂循环次数和真空度均对烫漂后百合的干燥特性有显著性影响,当蒸汽烫漂时间30 s,烫漂循环3次,真空度90 kPa时,百合烫漂充分,提高了细胞间的通透性并抑制PPO、POD酶的活性,烫漂后在60 ℃热风下干燥,最短为11.7 h;干燥后的百合片色泽L^*值为83.65、ΔE值为5.18,接近于新鲜百合色泽;复水比最高为1.49 g/g,水分有效扩散系数最大为6.85×10^-10 m²/s;综合评分最高为0.98。     

不同预处理方式对西兰花等外品热风干燥粉体性质的影响

为明确西兰花等外品热风干燥制粉工艺适宜预处理方式,分别采用蒸汽蒸制、热水烫漂、切小丁的预处理方式制备西兰花等外品热风干燥粉体(the hot air drying powder of broccoli defective product,简称HBD粉),研究了不同预处理方式对HBD粉粉体性质的影响。结果表明:烫漂对HBD粉色泽保持效果最好,V_C保留量较高,但溶解性较差。烫漂10 s粉体流动性较差。烫漂30 s粉体较难吸湿,更利于压片成型和干燥保存;蒸汽蒸制粉体水溶性指数较大。蒸汽10 s粉体平均粒径最小,流动性较差,总糖、还原糖含量最高,吸湿能力最强,达22.8%。蒸汽30 s更利于压片成型;小丁粉体膨胀力、持水力较强。经烫漂10 s、蒸汽10 s预处理的HBD粉适宜作为功能配料添加到食品中或吸附于食品表面,经烫漂30 s、蒸汽30 s预处理的HBD粉体适宜片剂、胶囊等产品剂型加工。     

脱水黄花菜加工过程中的预处理工艺研究

以黄花菜的主栽品种鲜猛子花为材料,在测定过氧化物 酶及多酚氧化酶活力的基础上,通过对热水、蒸汽及微波 灭酶等灭酶方法的研究,确定了蒸汽漂烫70～80s的最佳 灭酶工艺条件;同时,以护色剂种类、护色剂浓度、浸泡时 间为影响因素,进行了三因素三水平试验,得到了将原料 浸泡在0.5％的柠檬酸溶液中45min的最佳护色工艺。     

Investigation of hot air-assisted radio frequency heating as a simultaneous dry-blanching and pre-drying method for carrot cubes

Hot air-assisted radio frequency (HA-RF) heating was studied as a novel method for simultaneous dry-blanching and pre-drying of carrot cubes, and ultrasound-assisted osmotic dehydration (UOD) was also investigated as an improved conventional pre-drying method for comparison. After conventional hot water blanching, UOD was optimized by orthogonal experiment and after 30.0 min UOD treatment at optimal condition (10% sodium chloride, 40% sucrose and 1,4 solid-liquid ratio), moisture content of carrot cubes decreased to 58.5% (w.b.); and after 9.0–12.0 min HA-RF treatment, moisture content decreased to 60.9–71.9% (w.b.) and enzyme activity (peroxidase-POD) could be reduced to <5% at the same time. UOD was better in lowering water activity and retaining redness of carrot cubes, while HA-RF treated samples had higher vitamin C content and better texture. Besides, HA-RF pre-treatment had lower energy consumption (<0.20 kW∙h/kg) than that of hot water blanching plus UOD treatment (0.67 kW∙h/kg). This study indicated that HA-RF was an effective simultaneous dry-blanching and pre-drying method for carrot cubes.Industrial relevanceThis study proposed and investigated hot air-assisted radio frequency (HA-RF) heating as a new simultaneous dry-blanching and pre-drying method for carrots cubes. This technology may replace the conventional blanching and the following pre-dewatering or 1st stage drying process, since HA-RF pretreatment maintained good quality of carrot cubes and had lower energy consumption, and most importantly, this method can blanch and partially dehydrate samples at the same time without using water. Therefore, it holds great potential as the industrial pre-treatment method for drying of fruits and vegetables.     

Chemical and physical pretreatments of fruits and vegetables: Effects on drying characteristics and quality attributes – a comprehensive review

Pretreatment is widely used before drying of agro-products to inactivate enzymes, enhance drying process and improve quality of dried products. In current work, the influence of various pretreatments on drying characteristics and quality attributes of fruits and vegetables is summarized. They include chemical solution (hyperosmotic, alkali, sulfite and acid, etc.) and gas (sulfur dioxide, carbon dioxide and ozone) treatments, thermal blanching (hot water, steam, super heated steam impingement, ohmic and microwave heating, etc), and non-thermal process (ultrasound, freezing, pulsed electric field, and high hydrostatic pressure, etc). Chemical pretreatments effectively enhance drying kinetics, meanwhile, it causes soluble nutrients losing, trigger food safety issues by chemical residual. Conventional hot water blanching has significant effect on inactivating various undesirable enzymatic reactions, destroying microorganisms, and softening the texture, as well as facilitating drying rate. However, it induces undesirable quality of products, e.g., loss of texture, soluble nutrients, pigment and aroma. Novel blanching treatments, such as high-humidity hot air impingement blanching, microwave and ohmic heat blanching can reduce the nutrition loss and are more efficient. Non-thermal technologies can be a better alternative to thermal blanching to overcome these drawbacks, and more fundamental researches are needed for better design and scale up.     

超高(静)压处理对果蔬理化性质的影响

超高（静）压（以下简称超高压）技术用于乳制品、果蔬汁等的报道已有很多，而超高压用于固态食品是近几年研究的新课题。综述了超高压对果蔬质构的影响。超高压可以引起果蔬变软、褐变。但是超高压比热烫对果蔬的质构影响小。     

Conventional and novel peeling methods for fruits and vegetables: A review

This review explores the effects of various peeling technologies on the peeling performance of fruits and vegetables and peeled product quality. The peeling methods include conventional peeling approaches using hot-water, steam and lye and novel peeling techniques employing infrared radiation heating, ohmic heating and power ultrasound. The working principles, technology characteristics, the major factors affecting the processing efficacy, and limitations of conventional and novel peeling approaches are identified and discussed. Infrared radiation heating, ohmic heating and ultrasound-assist peeling methods have been successfully used to the peeling of tomatoes and other fruits and vegetables. The novel technologies can reduce the use of lye and can improve peeling performance and peeled product quality compared to conventional peeling. The process conditions and food properties are the major determinants affecting the processing efficacy. Future research needs are proposed to scaling-up the technology and exploring other technology used for peeling.Industrial relevance: As a key operation in the fruits and vegetables processing industry, peeling not only directly affects product quality, but also influences the processing cost and the management cost of waste generated by peeling. An unsuitable peeling process may result in low peeling efficiency and quality, high water and energy consumption, and high discharge of waste liquid, leading to the decline of economic benefits and environmental issues. The current work provides important information for selecting suitable peeling methods for high quality and safe products.     

元分析方法评估食品加工对果菜中农药残留的作用

本文采用元分析方法评估食品加工对果类蔬菜中农药残留作用。通过多个数据库文献搜索、数据采集、元分析统计计算,获得特定食品加工方式对果菜中农药残留作用的响应比值、实验间变异及置信区间,并对实验数据进行了同质性Q检验。结果显示研究所取数据具有同质性,自来水清洗、多种溶液清洗、去皮、水煮、清炒、漂烫、烘烤对果菜中农药作用的响应比值均小于0.6,说明食品加工对去除果菜中农药残留有较好作用,可达到40%以上;其中漂烫和烘烤的响应比值分别为0.04和0.01,农药去除效果极佳,可达到95%以上;与自来水清洗相比,乙酸溶液、氯化钠溶液、碳酸钠溶液、碳酸氢钠溶液清洗对农药去除均有较好的效果。元分析获得食品加工对果菜中农药残留作用的响应比值可作为加工因子用于食品安全风险评估中,并可指导果菜安全消费。     

Vacuum-steam pulsed blanching (VSPB) softens texture and enhances drying rate of carrot by altering cellular structure,pectin polysaccharides and water state

As a new type of blanching technology, vacuum-steam pulsed blanching (VSPB) has higher blanching efficiency and quality, but the mechanism of this technology on texture softening and drying enhancement is still unclear. In this study, the mechanism was revealed from texture, pectin, nanostructure, cell ultrastructure, calcium, and water state. Results revealed that VSPB treatment reduced the hardness and chewiness, increased water-soluble pectin, decreased sodium‑carbonate-soluble and chelate-soluble pectin concentration, and resulted in depolymerization and degradation of pectin nanostructure. However, transmission electron microscopy showed that blanching damaged the cell wall structure and the integrity of the middle layer. Scanning electron microscope - Energy dispersive X-ray spectroscopy measurement observations indicated that lipid droplets containing calcium ions were formed under the action of VSPB. In addition, low field nuclear magnetic resonance showed that the redistribution of moisture in carrot was facilitated by VSPB. The findings reveal the mechanism of texture softening and drying rate enhancement driven by blanching.Industrial relevanceThermal blanching is an essential thermal treatment for many fruits and vegetables processing. Hot water blanching and steam blanching are the two most frequently employed blanching methods due to simple to establish and easy to operate. However, hot water and steam blanching holds several disadvantages, e.g., hot water blanching requires a huge amount of water and generates an excessive amount of wastewater, particularly loss of water-soluble nutrients during blanching due to leaching and diffusion, while for steam blanching, the existence of air and water vapor among the piled materials leads to low blanching efficiency and un-uniform heating. VSPB is an innovative steam blanching method. In the VBSP process, the air and water vapor are expelled by the vacuum pump to facilitate steam deep penetration in the materials, particularly the piled materials, so as to improve blanching efficiency and uniformity. Previous study indicated VSPB could soften texture and reduce the drying time of carrot, but the mechanism was not clear. The current work reveal that VSPB softens texture and enhances drying rate of carrot via micro-, ultra-structure modification, pectin polysaccharides degradation and changes of water state. The findings have important implications for understanding and controlling the blanching triggered texture formation and drying enhancement.     

Frozen Vegetable Quality as Influenced by High Temperature Short Time (HTST) Steam Blanching

Quality differences in processed vegetables can be controlled with high pressure steam blanching (HTST). In addition, HTST blanching required significantly less energy to blanch vegetables than water blanching. HTST-blanched vegetables displayed quality parameters distinctly different than water-blanched vegetables. Differences in quality parameters were highly dependent upon the vegetable being blanched and the pressure and time of the HTST blanch. The quality of vegetables were similar between water and HTST blanching treatments, but by controlling the pressure and time of the HTST blanch, quality characteristics could be changed to meet individual requirements. High quality frozen vegetables can be produced with HTST steam blanching but quality is dependent upon the particular vegetable and pressure and time of the HTST steam blanch.     

水静压封式蒸煮工艺探讨

<正> 所谓蒸煮,是指短时间的热烫程序,与预热不同。蒸煮可以抑制植物类食品如水果、果仁和蔬菜中酶和细菌的活动,亦能使产品的外皮变得松软、色泽变浅或变白,有助于后加工工序。蒸煮效应是通过产品与热水、蒸汽或其他气体直接接触,在适当的时间和温度控制下完成。本文集中介绍以蒸汽为媒介的蒸煮加工技术,以及密封绝热的环境对蔬菜蒸煮的影响。     

Blanching Leafy Vegetables with Electromagnetic Energy

Application of radio frequency, microwave, microwave-steam and infrared energy for blanching of leafy vegetables (endive and spinach) was studied and compared with conventional hot water and steam blanching. The quality of vegetables both frozen and sterilized was evaluated by instrumental and sensory analysis. Effects of blanching methods were most pronounced in frozen products. No quality differences occurred for infrared and radio frequency treatments. However, microwave energy alone or in combination with steam in the blanching process improved vitamin C retention, gave higher Instron force values and better sensory characteristics.     

An improved vacuum-steam pulsed blanching machine design and garlic scape blanching verified experiment

Vacuum-steam pulsed blanching (VSPB) is an emerging blanching method resulting in high efficiency and product quality. However, inconvenient loading, small loading capacity, uneven rinsing and imprecise control hinder its application in food industry. Therefore, the current work aimed to design a VSPB machine, including selection of components, building a control system and designing a steam nozzle in order to increase the load capacity and improve device control. For this purpose, a horizontal blanching chamber with internal nozzle was designed and optimized using CFD method. The vacuum chamber design required a more evenly distributed steam inlet. A water-sealing vacuum pump, a cooling device and a hardware system were developed. The distribution of steam released from the nozzle in the chamber was numerically investigated by solving the three-dimensional Reynolds-averaged Navier-Stokes equations, with a velocity uniformity index value of 0.448. The validation blanching test was conducted using garlic scape as the test material. The steam holding time and the number of cycles significantly affected (p < 0.05) the color of the garlic scapes. Peroxidase (POD) activity decreased with the increase of blanching cycles until the enzymes were completely inactivated. VSPB significantly decreased (p < 0.05) the lignin content of the garlic scapes. The findings indicate that the best results were obtained after 2 cycles of VSPB and steam holding time of 30 s.Industrial relevanceHot water and steam thermal blanching are the two most frequently used blanching methods in food processing. Generally, they are used as a pretreatment before drying, freezing or canning of different fruits and vegetables. In current work, an improved vacuum-steam pulsed blanching machine was designed and the validation blanching test with garlic scape as the material indicated that VSPB operation was effective in preventing the synthesis of lignification in garlic scapes. By considering enzyme inactivation, lignification, color, and other quality attributes, 2 cycles of VSPB and steam holding for 30 s were proposed as the optimal VSPB conditions.