Mathematical Modeling of the Convective Drying of Fruits and Vegetables

A proposed mathematical model, based on physical and transport properties and mass and energy balances, was developed for unsteady transport of momentum, heat and mass in granular beds of agricultural products (fruits and vegetables) under convective drying conditions. The model utilized water sorption isotherm equations and the change in solid density due to shrinkage. The unsteady-state differential equations for temperature and moisture profiles within the product were numerically solved using a central finite difference scheme. Experimental data on drying conditions and product drying rates agreed with the calculated results. A design and operation parameters optimization scheme, tested for grapes, resulted in minimized drying time and high quality dried product.     

贮藏实践中的失败事例与分析

<正> 改革开放后尤其是近年来,随着我国经济实力的空前提高和社会对保鲜技术的巨大需求,果蔬贮藏保鲜业得到了迅速的发展。据不完全统计,我国果品总贮量1200万吨,约占果品总产量的20%,其中冷藏量约800万吨。初步估计全国已经气调贮藏150万吨,拥有气调库80万吨,仅山东省胶东地区已经突破12万吨。随着果蔬业逐渐成为广大农村和农民主要的经济来源,这种冷库与气调库等贮藏设施的     

Maintaining Antioxidant Potential of Fresh Fruits and Vegetables After Harvest

The consumption of fruits and vegetables has increased in the past few years, not only because of their attractive sensorial properties, but also for their nutritional and health benefits. Antioxidants are compounds found in fresh fruits and vegetables, and evidence of their role in the prevention of degenerative diseases is continuously emerging. However, the antioxidants in some fruits and vegetables can be lost during handling after harvest, even during minimal processing and storage. In this sense, postharvest treatments are needed to preserve the quality and antioxidant potential of fresh produce. Postharvest treatments and technologic strategies (including ultraviolet light, controlled and modified atmospheres, heat treatments, and application of natural compounds, such as edible coatings, active packaging, microencapsulation, and nanoemulsion) have shown positive and promising results to maintain fruit and vegetable antioxidant potential. The purpose of this review is to analyze and propose the application of postharvest strategies to maintain, or even improve, the antioxidant status of fruits and vegetables, thus offering options to maximize health benefits to consumers.     

果蔬功能因子及保健食品的发展

果蔬含有丰富的保健食品功能因子，具有很高的营养价值和医疗保健作用。本文概述了果蔬保健食品功能因子的研究现状，展望了果蔬保健食品的发展趋势。     

常见果蔬的抗氧化方法研究进展

综述了常见果蔬的抗氧化机理以及果蔬中抗氧化物质的测定方法,通过研究果蔬的抗氧化能力找到优良的抗氧化物质。     

果蔬涂膜保鲜的研究现状

本文介绍了糖类、脂类、蛋白类及复合类涂膜保鲜剂的应用发展状况．并通过对各种涂膜保鲜剂优缺点的比较,力求寻求较为适合有效的果蔬涂膜材料,为涂膜保鲜研究提供一些参考性建议。分析了涂膜保鲜技术在发展过程中存在的问题,并阐述了涂膜保鲜技术的未来发展趋势。     

臭氧在果蔬贮藏保鲜上的应用

臭氧是一种强氧化剂,具有广谱、高效的杀菌作用,介绍了臭氧的理化性质和产生方法、臭氧对果蔬的保鲜机理如杀菌、诱导抗病性、降解有害气体以及在果蔬上的保鲜效果。     

Dietary Fibers from Fruits and Vegetables and Their Health Benefits via Modulation of Gut Microbiota

Dietary fibers (DFs) regulate host health through various mechanisms related to their dietary sources, specific physicochemical structures, fermentability, and physiological properties in the gut. Considering the numerous types and sources of DFs and their different physicochemical and physiological properties, it is challenging yet important to establish the key mechanisms for the beneficial health effects of DFs. In this review, the types and structures of DFs from different fruits and vegetables were summarized and the effects of different processing methods on DF properties were discussed. Moreover, the impacts of DFs on gut microbial ecology, host physiology, and health were described. Understanding the complex interaction between different DFs and gut microbiota is vital for personalized nutrition. It is also important to comprehend factors influencing gut microbiota and strategies to regulate the microbiota, thereby augmenting beneficial health responses. The exploration of molecular mechanism linking DFs, gut microbiota, and host physiology may allow for the identification of effective targets to fight against major chronic diseases.     

蒲公英的营养与保健功能

蒲公英是常见的药用野菜,具有药用及保健的双重功效。本文综述了蒲公英的营养价值、保健功能以及开发前景。     

Osmotic Dehydration of Tropical Fruits and Vegetables

Because of the microstructural complexity of plant tissue, osmotic dehydration cannot simply be explained as a pure osmotic process in which cell membranes act as a semipermeable barrier allowing water to pass through. Instead, osmotic dehydration is considered a process in which many simultaneous mechanisms, acting at different levels, are responsible for mass transport. Different compositional and structural profiles are induced in fruits and vegetables, depending on process variables and the tissue microstructure. Compositional-structural profiles that are developed with gas-liquid exchanges in the tissue during osmotic process have a significant impact on physical (optical), textural and chemical properties (e.g., flavour profile) of the final product, which is in part influenced by the differences in the number of cells that are altered and unaltered during the treatment. This review focuses on changes in the physical, chemical, and cellular structure of fruits and vegetables, some technologies commonly applied to increase mass transfer during osmotic dehydration (OD), potentials and industrial applications of OD, and the challenges of osmo-drying technology.     

Gloss Evaluation of Curved-surface Fruits and Vegetables

Gloss measurements are used to evaluate the quality and appearance of a product, especially in cases where esthetic appearance is of importance. Most commercial glossmeters are designed for measuring products of flat surface and therefore are not suitable for food products because of their uneven, curved surface. A new generation of commercial glossmeters is recently available for confined areas, curved surfaces, and surfaces that are not uniform. This article provides a brief review of gloss measurement principles and methods for fresh fruits and vegetables. It reports on the gloss measurement of apples and other fresh products using a commercial glossmeter and a specially designed spectrometer-based gloss measurement prototype integrated with imaging and automatic sample positioning capabilities. Results showed that the prototype had a nonlinear relationship with standard gloss measurements. With the new setup, the gloss of apples was measured with the repeatability for 90% of the measurements being better than 16%, calculated as the ratio of the difference between maximum and minimum gloss values to the mean value in percent. Further research is needed to simplify the imaging/mechanical configuration and improve the coordinate calculation algorithm to achieve more accurate, repeatable gloss measurements.     

植物精油对果蔬霉菌的抑制及在果蔬保鲜中的应用

精油是一类植物源的次生代谢产物,是萃取于植物的叶、花、根、茎或果实等不同组织部位的具有挥发性油状液体的芳香类物质,因其具有广谱的抑菌活性,在果蔬贮藏保鲜中得到广泛应用。该文综述了植物精油对果蔬中霉菌的抑菌效果及其抑菌机理,简要分析了精油采前喷洒法、精油浸渍法、精油熏蒸处理、精油微胶囊包埋法、精油复合涂膜和精油保鲜纸等多种用于果蔬保鲜的处理方法及作用效果,最后对植物精油的发展前景作出展望,为植物精油在果蔬保鲜中的研究和应用提供理论基础。     

蒲公英绿原酸及其包合物对葡萄保鲜作用的研究

采用自己制备的高纯度蒲公英绿原酸及其白芨多糖和β-环糊精包合物对葡萄果实进行保鲜作用的研究。结果表明:三者均能有效降低贮果的失重率、霉变率,明显抑制了贮果中总有机酸和维生素C(VC)含量进行性减少的趋势,较大程度上维护贮果细胞中超氧物歧化酶(SOD)活性的稳定性。对贮果的保鲜效应与所应用的绿原酸及其包合物的浓度呈显著的正相关性,并且包合物比未包合的绿原酸效果好,其中尤以白芨多糖绿原酸包合物的保鲜效果更好。这可能与绿原酸包合物对氧对光的稳定性增加相关,白芨多糖包合物还在贮果表面形成保护性薄膜。     

复合可食性膜在果蔬保鲜中应用研究进展

介绍糖类复合膜、蛋白质类复合膜以及混合复合膜的保鲜机理及其在果蔬保鲜中的应用,为果蔬保鲜技术的发展和应用提供技术借鉴。     

果蔬中复硝酚盐残留量检测方法的建立

建立了固相萃取-气相色谱-电子捕获检测水果蔬菜中复硝酚盐残留量的方法,样品经甲醇-水-磷酸体系提取,HLB固相萃取柱净化,乙酸酐衍生,气相色谱-电子捕获检测器测定,外标法定量,液相色谱-质谱定性。结果表明,在0.01～1.0mg/L范围内线性良好,方法定量限为0.01mg/kg。对草莓、苹果、番茄、马铃薯、菠菜、茄子6种水果蔬菜进行3个水平(0.01、0.02、0.05mg/kg)的添加回收,回收率在81.0%～106.6%之间,相对标准偏差3.9%～8.1%,该方法可靠、稳定,可满足水果蔬菜中复硝酚盐残留检测与确证的需要。     

可食性膜及其在果蔬保鲜中的应用

本文概述了可食性膜的分类、特性及其影响因素以及成形技术,并就其在果蔬保鲜中的应用进行了综述。     

潮汕果蔬腌制品在传统工艺中NO2-前后量的相关分析

以盐酸萘乙二胺法测定了桃、黄皮、橄榄、柑皮、柑、豆角、萝卜的腌制样品和新鲜样品中NO2-的含量.结果表明,其中陈皮(即柑皮制品)的NO2-的含量最高,萝卜的腌制样品和新鲜样品中的NO2-含量相差不大,黄皮的新鲜样中NO2-的量比腌制品高,并模拟洗涤、腌制工序,分别以柑皮和萝卜为例,测前后NO2-量的变化程度.     

果蔬采后内部损伤无损检测研究进展

果蔬产品含人体所必需的一些维生素、无机盐及植物纤维等营养元素,是人们日常膳食的重要组成部分。果蔬在采后处理过程中容易遭受机械损伤,不仅会降低果蔬自身外观品质,而且使果蔬容易受到真菌或细菌侵染,造成腐烂(如晚疫病、干腐病、软腐病等),影响其食用安全性。受侵染果蔬在运输、贮存等过程中会感染正常果蔬,进一步扩大经济损失。由碰压引起的内部损伤因损伤果蔬和正常果蔬外部特征差别不明显,容易相互混杂,对果蔬外观及食用品质造成潜在危害。因此,识别并剔除有内部损伤的果蔬日益引起国内外学者的注意。本文从果蔬损伤后发生的生理和物理变化角度入手,阐述了无损检测技术应用于内部损伤检测的机理,并综述了利用光、热、声和电磁学特性检测果蔬采后内部损伤的研究进展,最后指出了研究难点和今后研究方向。     

果蔬对亚硝酸盐清除作用的研究进展

发色剂亚硝酸盐对腌腊肉制品有护色、改善风味、防止腐败和预防肉毒中毒的重要作用。但是肉制品中过量添加发色剂,可致亚硝酸盐急性中毒,同时亚硝酸盐也是形成强致癌物亚硝胺的前提。因此,清除亚硝酸盐或阻断亚硝胺的合成是促进膳食健康的有效途径之一。将近年来有关果蔬清除亚硝酸盐和阻断亚硝胺形成的研究进展进行综述,为腌腊肉制品的合理搭配、科学烹饪提供依据,对提高腌腊肉制品食用安全具有重要意义。     

果蔬酚类物质抗氧化活性研究

采用基于不同机理的抗氧化方法对果蔬中常见的酚类物质单体,包括黄烷酮、多甲氧基黄酮、黄酮醇、酚酸等活性成分行了较全面的评价。结果显示酚类物质的抗氧化能力与其结构有密切关系。对天然产物或抗氧化剂的抗氧化能力的评价应该采用至少两种机理不同的抗氧化方法进行测试,才能取得较为客观有效的结论。