物理场辅助渗透脱水技术及其在果蔬干燥中的应用

渗透脱水是一种促进果蔬干燥、保持果蔬感官和功能特性、延长果蔬货架期的非热加工技术。渗透脱水技术的主要缺点是传质效率低,物理场辅助渗透脱水技术可有效地提升渗透脱水效率。物理场辅助渗透脱水技术包括:超声波辅助技术、真空辅助技术、高静水压和高压脉冲电场辅助技术,是近年来果蔬干燥研究的热点。通过研究归纳国内外相关文献,分别从果蔬渗透脱水的机理及其传质效率影响因素、物理场辅助渗透脱水技术及动力学模型、物理场辅助渗透脱水在果蔬干燥的应用3个方面综述了物理场辅助渗透脱水技术近年来的研究进展,总结应用中存在的问题,提出未来发展方向。     

蔬干燥前处理技术的应用及研究进展

目前,针对果蔬干制加工中存在的能耗高、时间长、营养成分损失严重等问题,主要通过干燥技术的创新以及干燥设备的研发予以不断改善,而干燥前处理技术在国内发展相对缓慢。干燥前处理技术是指通过物理、化学、生物等技术手段对物料进行处理,从而起到加快物料干燥速率、提高产品外观及营养品质、延长货架期的作用。目前常用的果蔬干燥前处理技术有:热烫、冻融、渗透、化学试剂、超声、超高压、高压脉冲电场、二氧化碳浸渍处理等。本研究针对上述几种前处理技术的原理、特点进行综述,对比不同前处理技术的作用机制及适用果蔬的种类,并展望了不同前处理技术的发展前景与趋势,以期为果蔬干燥新技术的研究与开发提供指导意见。     

Recent developments in high-quality drying of vegetables,fruits, and aquatic products

Fresh foods like vegetables, fruits, and aquatic products have high water activity and they are highly heat-sensitive and easily degradable. Dehydration is one of the most common methods used to improve food shelf-life. However, drying methods used for food dehydration must not only be efficient and economic but also yield high-quality products based on flavor, nutrients, color, rehydration, uniformity, appearance, and texture. This paper reviews some new drying technologies developed for dehydration of vegetables, fruits, and aquatic products. These include: infrared drying, microwave drying, radio frequency drying, electrohydrodynamic drying, etc., as well as hybrid drying methods combining two or more different drying techniques. A comprehensive review of recent developments in high-quality drying of vegetables, fruits and aquatic products is presented and recommendations are made for future research.     

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、...     

Effect of Processing on Phenolic Antioxidants of Fruits,Vegetables, and Grains—A Review

Understanding the influence of processing operations such as drying/dehydration, canning, extrusion, high hydrostatic pressure, pulsed electric field, and ohmic heating on the phytochemicals of fruits, vegetables, and grains is important in retaining the health benefiting properties of these antioxidative compounds in processed food products. Most of the previous investigations in the literature on the antioxidants of fruits, vegetables, and grains have shown that food-processing operations reduced the antioxidants of the processed foods, which is also the usual consumer perception. However, in the last decade some articles in the literature reported that the evaluation of nutritional quality of processed fruits and vegetables not only depend on the quantity of vitamin C but should include analyses of other antioxidant phytochemicals and antioxidant activity. Thermal processing increased the total antioxidant activity of tomato and sweet corn. Most importantly, analysis also depends on the condition, type, and mechanism of antioxidant assays used. This review aims to provide concise information on the influence of various thermal and nonthermal food-processing operations on the stability and kinetics of health beneficial phenolic antioxidants of fruits, vegetables, and grains.     

Use of pulsed electric field pre-treatment to improve dehydration characteristics of plant based foods

Conventional dehydration of fruits and vegetables affects their physical and biochemical status leading to shrinkage, change of colour, texture and taste. Alteration of the physical properties of foods with minimal influence on the quality could be a means of reducing drying time, minimising quality degradation and saving energy. Increasing consumer markets for minimally processed fruits and vegetables have prompted researchers to study combined methods as preservation techniques. Pulsed electric field is one of the more promising non- thermal processing method inducing membrane permeabilisation within a very short time (μs to ms range) leaving the product matrix largely unchanged while positively affecting mass transfer in subsequent processing of foods. Rapid and accurate on-line determination of the state of cell membrane systems is important in optimising various processes (i.e. minimizing cell damage in minimal processes, monitoring disruption for mass transfer purposes and inducing biosynthetic stress/wound reactions/responses). This paper reviews recent work on the use of pulsed electric fields as an upstream process in dehydration and rehydration of plant based foods. An effective and simple method for quantifying extent of membrane permeabilization is also discussed and suggestions for future work are highlighted.     

不同聚合度糖渗透对苹果片干燥特性及品质的影响

渗透作为果蔬干燥预处理方式,能减少干燥时间、提高产品质量。为探究不同聚合度糖渗透对苹果片热风-压差闪蒸联合干燥特性及产品品质的影响,采用单糖(果糖、葡萄糖)、二糖(蔗糖、麦芽糖)、三糖(棉子糖)、四糖(水苏糖)对苹果片进行渗透和热风-压差闪蒸联合干燥实验。对渗透苹果片热风干燥特性曲线进行干燥动力学模型拟合,选择热风干燥至水分比为0.1的样品进行压差闪蒸处理,并对所得苹果脆片质构和色泽进行分析。结果表明:除麦芽糖外,随着渗透所用糖的聚合度增加,渗透效率降低;Page模型能准确地(R~20.998)描述渗透后苹果片的热风干燥规律;与未渗透处理的对照组样品相比,实验所选不同聚合度糖能显著提高苹果脆片的硬度,其中棉子糖和水苏糖对脆度提高作用最显著;此外,渗透可以保护苹果片色泽,但不同糖液渗透后苹果片的ΔE差异并不显著。本研究可为果蔬干燥渗透预处理的糖种类的选择提供理论依据。     

热带亚热带果蔬渗透脱水研究进展

从渗透脱水的影响因素、渗透脱水对热带亚热带果蔬的影响以及渗透脱水传质动力学三个方面综述了果蔬渗透脱水的研究进展,其中重点介绍了渗透脱水的影响因素,同时对果蔬渗透脱水技术的局限性及其应用前景进行了探讨。     

Solute Transfer in Osmotic Dehydration of Vegetable Foods: A Review

While various mechanisms have been proposed for the water transfer during osmotic dehydration (OD), little progress has been made to understand the mechanisms of solute transfer during osmotic dehydration. The transfer of solutes has been often described only by the diffusion mechanism; however, numerous evidences suggest the participation of a variety of mechanisms. This review deals with the main issues of solute transfer in the OD of vegetables. In this context, several studies suggest that during OD of fruits and vegetables, the migration of solutes is not influenced by diffusion. Thus, new theories that may explain the solute transport are analyzed, considering the influence of the plant microstructure and its interaction with the physicochemical properties of osmotic liquid media. In particular, the surface adhesion phenomenon is analyzed and discussed, as a possible mechanism present during the transfer of solutes in OD.     

Recent Development in Osmotic Dehydration of Fruit and Vegetables: A Review

Osmotic dehydration of fruits and vegetables is achieved by placing the solid/semi solid, whole or in pieces, in a hypertonic solution (sugar and/or salt) with a simultaneous counter diffusion of solutes from the osmotic solution into the tissues. Osmotic dehydration is recommended as a processing method to obtain better quality of food products. Partial dehydration allows structural, nutritional, sensory, and other functional properties of the raw material to be modified. However, the food industry uptake of osmotic dehydration of foods has not been extensive as expected due to the poor understanding of the counter current flow phenomena associated with it. However, these flows are in a dynamic equilibrium with each other and significantly influence the final product in terms of preservation, nutrition, and organoleptic properties. The demand of healthy, natural, nutritious, and tasty processed food products continuously increases, not only for finished products, but also for ingredient to be included in complex foods such as ice cream, cereals, dairy, confectionaries, and bakery products.     

可食性活性涂膜在鲜切果蔬保鲜中的应用

可食性涂膜是一种由天然可食性材料制成的选择透过性薄膜,具有调节果蔬内部气体交换、减少水分损失、降低腐烂率及延长货架期的特性,在果蔬包装及保鲜领域中已引起广泛关注。鲜切果蔬具有新鲜、方便、快捷等特点,已在全球范围内广泛供应餐饮业及零售业。可食性涂膜作为多种食品添加剂的载体常应用于生鲜产品中,且将活性添加剂与可食性涂膜结合可以延长鲜切果蔬的货架期,提高果蔬品质,减少果蔬表面致腐及致病菌增长的风险。可食性活性涂膜将作为一种绿色、安全、营养的保鲜技术,并将应用于鲜切果蔬保鲜领域的研究。本文综述了可食性涂膜的分类及其添加的抗菌剂、抗氧化剂、塑形剂、营养素等活性成分在鲜切果蔬保鲜中的应用,旨在开发用于鲜切果蔬保鲜的功能性可食性涂膜。     

Recent advances in pressure modification-based preservation technologies applied to fresh fruits and vegetables

Fresh fruits and vegetables are important parts of the human diet. The consumer demand for fruits and vegetables is increasing due to their rich nutritional value, appealing taste, and healthy perception. However, due to their highly perishable nature, appropriate preservation technologies must be developed to meet the consumer’s demand for healthy, additive-free, microbiologically safe, and high quality fresh fruits and vegetables. The preservation technologies based on modification or control of pressure alters the normal atmospheric pressure of the preservation environment. The materials to be preserved are subjected to either very high or low pressure to extend their shelf life. The mechanism, advantages, and limitations of pressure modification-based preservation methods such as high hydrostatic pressure, hyperbaric treatment, vacuum cooling, hypobaric storage, and vacuum packaging focusing on their applicability to fresh fruits and vegetables have been reviewed. This review suggests that these technologies have potential to extend the shelf life and achieve a better preservation of the quality of fresh fruits and vegetables.     

Modeling the Thin‐Layer Drying of Fruits and Vegetables: A Review

The drying of fruits and vegetables is a complex operation that demands much energy and time. In practice, the drying of fruits and vegetables increases product shelf‐life and reduces the bulk and weight of the product, thus simplifying transport. Occasionally, drying may lead to a great decrease in the volume of the product, leading to a decrease in storage space requirements. Studies have shown that dependence purely on experimental drying practices, without mathematical considerations of the drying kinetics, can significantly affect the efficiency of dryers, increase the cost of production, and reduce the quality of the dried product. Thus, the use of mathematical models in estimating the drying kinetics, the behavior, and the energy needed in the drying of agricultural and food products becomes indispensable. This paper presents a comprehensive review of modeling thin‐layer drying of fruits and vegetables with particular focus on thin‐layer theories, models, and applications since the year 2005. The thin‐layer drying behavior of fruits and vegetables is also highlighted. The most frequently used of the newly developed mathematical models for thin‐layer drying of fruits and vegetables in the last 10 years are shown. Subsequently, the equations and various conditions used in the estimation of the effective moisture diffusivity, shrinkage effects, and minimum energy requirement are displayed. The authors hope that this review will be of use for future research in terms of modeling, analysis, design, and the optimization of the drying process of fruits and vegetables.     

脉冲电场预处理在果蔬干燥中的应用研究进展

脉冲电场（Pulsed Electric Field,PEF）作为新型的非热预处理技术，具有耗时短、能耗低、绿色环保等优良特性。本文综述了脉冲电场的作用机理及其作为预处理技术在果蔬干燥领域的应用，如热风干燥、冷冻干燥、微波干燥、渗透干燥、喷雾干燥和真空干燥。与未处理相比，PEF预处理可以提高脱水速率，降低生产成本，提高样品中营养成分的保留率，使干燥产品的品质更佳。但PEF存在参数与处理基质之间的特异性，预处理食品的安全性等问题，后续需加强PEF的参数匹配及安全性研究，为PEF预处理在果蔬干燥领域的深入研究提供新的思路和参考。     

Review of recent applications and research progress in hybrid and combined microwave-assisted drying of food products: Quality properties

Abstract

The growing concerns over product quality have increased demand for high quality dried food products and encouraged researchers to explore and producers of such products to implement novel microwave (MW)-assisted drying methods. This paper presents a critical review of the key principles and drawbacks of MW-assisted drying as well as needs for future research. In this article, recent research into application of microwaves as an alternative heat source, applications and progress in hybrid MW-assisted drying that rely on various drying media and combined two or three stages of MW-assisted drying for the preservation of food products is reviewed critically. The effect of different MW-assisted drying methods, conditions and initial pretreatments on the thermophysical properties, color, nutritional value and rehydration potential of dried food products is discussed in detail along with the discussion on how the material properties evolve and change in structure, color, and composition during MW-assisted drying and recent attempts at mathematical modeling of these changes made for different fruits and vegetables. It should be noted that most of the published results were obtained in laboratory-scale dryers. Pilot-scale testing is needed to bridge the gap between laboratory research and industrial applications to fulfill the potential for novel hybrid and combined MW-assisted drying methods and to expand their role in food processing.     

果蔬压差膨化过程中水分迁移的机理分析

水分的除去是食品干燥工业中最重要的指标之一,果蔬物料在干燥脱水中各工艺阶段的水分散失情况的确定,将有助于制定准确的工艺参数。果蔬压差膨化是一种新型的果蔬干燥工艺,通过以低温高压膨化设备为研究对象,根据其工艺参数并利用热力学相关定律,分析并计算出整个膨化操作过程中水分的迁移情况。结合示意图,给出了膨化过程中物料各阶段含水量。并根据分析,给出影响产品质量的冷凝水的处理方法,为果蔬压差膨化的工艺完善提供了理论基础。     

鲜切果蔬品质劣变影响因素及其可能机理

鲜切果蔬是指新鲜果蔬原料经预处理、清洗、切分、保鲜、包装和贮藏等多道工序制成的不影响其鲜活状态的一种制品。品质快速劣变是影响其货架寿命的主要原因。本文综述鲜切果蔬品质快速劣变的影响因素及其可能机理,旨在为鲜切果蔬贮藏保鲜新技术的建立和应用提供理论依据。     

Acceleration of mass transfer rates in osmotic dehydration of elephant foot yam (Amorphophallus paeoniifolius) applying pulsed-microwave-vacuum

The elephant foot yam slices were processed with combined pulsed-microwave-vacuum osmotic drying. Osmotic dehydration at ambient (28 °C and 45% RH) was carried out using different levels of sucrose concentration (30, 40, 50 and 60% w/w), salt concentration (5, 7.5, 10 and 12.5% w/w) and dehydration time (10, 20, 30, 50, 70, 90 and 120 min). During the osmotic dehydration, pulsed microwave vacuum (15 kPa pressure, 1 W/g power density and 1.853 pulsating ratio) was maintained for 2 min over the sample and solution to enhance the mass transfer. For this purpose, the osmotic dehydration experiments were conducted in the microwave-vacuum cavity. Azuara model predicted the moisture loss and solid gain by elephant foot yam slices during osmosis. It was observed that both the moisture loss and the solid gain increased with increasing concentration of the osmotic solution. The optimum conditions found in the process were 40% w/w sucrose concentration, 6% w/w salt concentration and 70 min osmotic dehydration time, resulting in to 42.80% moisture loss (initial weight) and 14.65% solid gain (initial weight). Further, samples were dried using microwave vacuum dryer up to moisture content of 5–6% d.b. by varying microwave power density (2, 4, 6 and 8 W/g) and pulsating ratio (1.312, 1.625, 1.983 and 2.250). Page model was fitted to the data to study the microwave vacuum drying kinetics. The microwave vacuum drying at 1.625 pulsating ratio with microwave power density 4 W/g yielded a product with the highest overall acceptability score. Guggenheim, Anderson and deBoer (GAB) model was used in the study of the sorption behavior of dehydrated elephant foot yam and shelf life prediction.Industrial relevanceThe production of elephant foot yam in India and South East Asia is comparatively higher than other vegetables. Although, it is nutritious product and good source of energy, food industries are not interested to process elephant foot yam using a time consuming traditional osmotic dehydration process followed by hot air drying. Therefore, present research work was undertaken from industry suggestion to develop accelerated osmotic dehydration process for elephant foot yam using novel pulsed-microwave-vacuum combination followed by finish drying by microwave-vacuum. This research has been carried out to decrease industrial processing time, energy consumption and improving quality of the product. Industry will start adopting this new hybrid process of drying elephant foot yam on large scale.     

脉冲强光杀菌技术在食品及包装材料中应用研究进展

脉冲强光是一种高效、环保的新型非热杀菌技术,在食品领域具有巨大的发展潜力。本文综述了脉冲强光技术的杀菌机理及其在果蔬、肉制品、乳制品、食品包装材料等领域中的应用,脉冲强光与其他保鲜技术的耦合效果,脉冲强光技术在食品工业中的应用实例以及脉冲强光使用的安全性。脉冲强光不仅能广泛杀灭多种致病菌而且基本不改变各类食品及食品包材的各项性质,在提高食品安全性和延长食品保质期方面有巨大的应用潜力,脉冲强光与其他保鲜技术的耦合与单一保鲜技术相比在杀菌效果、感官品质、营养素含量的保留等方面也都具有更好的效果。本文为研究者进一步了解脉冲强光杀菌技术、拓展其应用领域提供理论参考。     

Flavonoids in fruits and vegetables after thermal and nonthermal processing: A review

ABSTRACT

Consumers currently demand more nutritious food, which is minimally processed and naturally produced. Flavonoids are one of the major plant metabolites found throughout the plant kingdom, especially in fruits and vegetables. Flavonoids exert tremendous positive effects on health and protect against various diseases. Fruits and vegetables are difficult to store for a long period, owing to their perishable nature even at low temperatures. Therefore, processing is necessary to prolong their shelf lives and increase nutritional values. Thermal processing has been used in the food sector since ancient times. However, nonthermal processing has become more attractive to consumers and product developers recently, owing to the retention of beneficial health properties after nonthermal processing. The present review will address the effects of thermal and nonthermal processing methods such as blanching, drying, high-pressure processing, ultrasound, pulsed electric field, and ultraviolet irradiation on total and individual flavonoid content in fruits and vegetables. In addition, this text will elucidate the stability characteristics as well as bioavailability, cytotoxicity, and transformations of flavonoids during thermal and nonthermal treatments.