A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables

Phenolic compounds, ubiquitous in plants, are of considerable interest and have received more and more attention in recent years due to their bioactive functions. Polyphenols are amongst the most desirable phytochemicals due to their antioxidant activity. These components are known as secondary plant metabolites and possess also antimicrobial, antiviral and anti-inflammatory properties along with their high antioxidant capacity. Many efforts have been made to provide a highly sensitive and selective analytical method for the determination and characterisation of polyphenols. The aim of this paper is to provide information on the most recent developments in the chemical investigation of polyphenols emphasising the extraction, separation and analysis of these compounds by chromatographic and spectral techniques.     

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.     

蔬菜、水果中农药多残留检测方法研究

目的 建立蔬菜、水果中6种农药的气相色谱-质谱联用分析方法。方法 通过对其前处理、仪器条件的优化, 以及灵敏度、精密度和基质适用性的研究, 建立一种优化后的多种农药多残留检测方法; 该方法采用超声波萃取, 凝胶渗透色谱净化(gel permeation chromatography, GPC), 气相色谱-质谱联用(gas chromatography-mass spectrometry, GC/MS)分析。结果 6种农药在0.2~1.0 mg/L浓度范围内线性良好, 相关系数大于0.995。加标回收率在70.2%~105.7%之间, 相对标准偏差(relative standard deviation, RSD)均≤7%。结论 本研究建立的方法操作简便、灵敏度高、重现性好, 可以用于日常的检验工作。     

从果蔬中开发抗氧化剂及评价方法研究进展

综述了果蔬中起抗氧化作用的活性成分及其抗氧化和清除自由基的作用机理,介绍了几种目前常用的果蔬抗氧化作用评价方法及其采用这些方法所取得的研究结果。对于选择抗氧化活性测定的方法具有指导意义。     

Advanced preservation methods and nutrient retention in fruits and vegetables

Despite the recommendations of international health organizations and scientific research carried out around the world, consumers do not take in sufficient quantities of healthy fruit and vegetable products. The use of new, 'advanced' preservation methods creates a unique opportunity for food manufacturers to retain nutrient content similar to that found in fresh fruits and vegetables. This review presents a summary of the published literature regarding the potential of high-pressure and microwave preservation, the most studied of the 'advanced' processes, to retain the natural vitamin A, B, C, phenolic, mineral and fiber content in fruits and vegetables at the time of harvest. Comparisons are made with more traditional preservation methods that utilize thermal processing. Case studies on specific commodities which have received the most attention are highlighted; these include apples, carrots, oranges, tomatoes and spinach. In addition to summarizing the literature, the review includes a discussion of postharvest losses in general and factors affecting nutrient losses in fruits and vegetables. Recommendations are made for future research required to evaluate these advanced process methods.     

Invited review: Modelling quality changes of fruits and vegetables during drying: a review

Fruits and vegetables have received much attention as these materials have been reported to contain various phytochemicals, which are claimed to exert many health benefits. When extraction of bioactive compounds cannot be performed on fresh fruits and vegetables, drying needs to be conducted to keep the materials for later use. Dried fruits and vegetables have also been regarded as alternative fat‐free snacks and received more attention from the food industry during the past decade. This implies that not only nutritional changes, but also other changes including physical and microstructural changes are of importance and need to be optimised, preferably through the use of various modelling approaches. The objective of this article is to provide a brief review of some advances in modelling quality changes of fruits and vegetables during drying. These include modelling of nutritional, colour and selected physical changes. Approaches to monitoring and modelling microstructural changes are also mentioned.     

Anti-inflammatory effects of phytochemicals from fruits,vegetables, and food legumes: A review

Inflammation is the first biological response of the immune system to infection, injury or irritation. Evidence suggests that the anti-inflammatory effect is mediated through the regulation of various inflammatory cytokines, such as nitric oxide, interleukins, tumor necrosis factor alpha-α, interferon gamma-γ as well as noncytokine mediator, prostaglandin E₂. Fruits, vegetables, and food legumes contain high levels of phytochemicals that show anti-inflammatory effect, but their mechanisms of actions have not been completely identified. The aim of this paper was to summarize the recent investigations and findings regarding in vitro and animal model studies on the anti-inflammatory effects of fruits, vegetables, and food legumes. Specific cytokines released for specific type of physiological event might shed some light on the specific use of each source of phytochemicals that can benefit to counter the inflammatory response. As natural modulators of proinflammatory gene expressions, phytochemical from fruits, vegetables, and food legumes could be incorporated into novel bioactive anti-inflammatory formulations of various nutraceuticals and pharmaceuticals. Finally, these phytochemicals are discussed as the natural promotion strategy for the improvement of human health status. The phenolics and triterpenoids in fruits and vegetables showed higher anti-inflammatory activity than other compounds. In food legumes, lectins and peptides had anti-inflammatory activity in most cases. However, there are lack of human study data on the anti-inflammatory activity of phytochemicals from fruits, vegetables, and food legumes.     

Antimicrobial edible films and coatings for fresh and minimally processed fruits and vegetables: a review

The use of edible films and coatings is an environmentally friendly technology that offers substantial advantages for shelf-life increase of many food products including fruits and vegetables. The development of new natural edible films and coatings with the addition of antimicrobial compounds to preserve fresh and minimally processed fruits and vegetables is a technological challenge for the industry and a very active research field worldwide. Antimicrobial agents have been successfully added to edible composite films and coatings based on polysaccharides or proteins such as starch, cellulose derivatives, chitosan, alginate, fruit puree, whey protein isolated, soy protein, egg albumen, wheat gluten, or sodium caseinate. This paper reviews the development of edible films and coatings with antimicrobial activity, typically through the incorporation of antimicrobial food additives as ingredients, the effect of these edible films on the control of target microorganisms, the influence of antimicrobial agents on mechanical and barrier properties of stand-alone edible films, and the effect of the application of antimicrobial edible coatings on the quality of fresh and fresh-cut fruits and vegetables.     

Preservation effect of high pressure processing on ascorbic acid of fruits and vegetables: A review

High Pressure Processing (HPP) is a well‐established nonthermal technology for ensuring microbial safety and nutritional quality of foods. Ascorbic acid (AA) is highly labile antioxidant, susceptible to degradation when exposed to oxygen, change in pH, temperature, or pressure. Preservation of AA in fruit and vegetable products is a prime concern for food processors. This review summarizes recent data on the effect of HPP on AA content of different fruits and vegetables, and their products. In most of the food products, HPP has supported either preservation or better retention of AA after pressurization (400–600 MPa/5–10 min) at lower or room temperature. High pressure processed foods have demonstrated better stability of AA during refrigeration storage as compared to thermally processed ones. These studies establish the positive implications of HPP and justify its potential use as a promising preservation technique to safeguard AA in food products.     

Recent developments in high efficient freeze-drying of fruits and vegetables assisted by microwave: A review

Microwave heating has been applied in the drying of high-value solids as it affords a number of advantages, including shorter drying time and better product quality. Freeze-drying at cryogenic temperature and extremely low pressure provides the advantage of high product quality, but at very high capital and operating costs due partly to very long drying time. Freeze-drying coupled with a microwave heat source speeds up the drying rate and yields good quality products provided the operating unit is designed and operated to achieve the potential for an absence of hot spot developments. This review is a survey of recent developments in the modeling and experimental results on microwave-assisted freeze-drying (MFD) over the past decade. Owing to the high costs involved, so far all applications are limited to small-scale operations for the drying of high-value foods such as fruits and vegetables. In order to promote industrial-scale applications for a broader range of products further research and development efforts are needed to offset the current limitations of the process. The needs and opportunities for future research and developments are outlined.     

果蔬中多酚成分及其分析方法的研究进展

果蔬是膳食的重要组成部分,富含多种多酚功能活性成分。多酚是植物的次级代谢产物,具有多种功效。多酚由于其强抗氧化活性,使其具有抗菌、抗病毒和抗炎的作用。天然来源多酚的开发以及在食品中的应用已经成为研究的热点。多酚种类繁多,分离、鉴定较复杂,研究者为了得到高灵敏度、高选择性多酚分析方法进行了大量研究。本文简述了果蔬中的多酚成分,重点介绍了类黄酮、酚酸和单宁;综述了多酚分析方法最近研究进展,重点是基于色谱方法和分离技术的多酚的提取、分离和鉴定。以期为果蔬多酚在食品中的应用提供参考和思路。      

原花青素与果胶相互作用对果蔬加工特性的影响

原花青素、果胶作为果蔬中常见的功能成分,因具有良好的功能特性被广泛应用于食品工业。该文综述了原花青素与果胶之间共价、非共价相互作用机制,分析了原花青素和果胶结构、环境因素(温度、pH等)对相互作用的影响,以及相互作用对果蔬感官特性、功能特性、生物利用度的影响,并对二者相互作用未来研究方向进行展望。研究结果表明,二者相互作用对食品涩味,果汁果酒体系稳定性,复合物抗氧化活性,原花青素生物利用度等方面均存在一定的正向影响,这为果汁果酒澄清、稳定和食品营养添加剂开发等方面提供一定的参考。     

Emerging chemical and physical disinfection technologies of fruits and vegetables: a comprehensive review

Abstract

With a growing demand for safe, nutritious, and fresh-like produce, a number of disinfection technologies have been developed. This review comprehensively examines the working principles and applications of several emerging disinfection technologies. The chemical treatments, including chlorine dioxide, ozone, electrolyzed water, essential oils, high-pressure carbon dioxide, and organic acids, have been improved as alternatives to traditional disinfection methods to meet current safety standards. Non-thermal physical treatments, such as UV-light, pulsed light, ionizing radiation, high hydrostatic pressure, cold plasma, and high-intensity ultrasound, have shown significant advantages in improving microbial safety and maintaining the desirable quality of produce. However, using these disinfection technologies alone may not meet the requirement of food safety and high product quality. Several hurdle technologies have been developed, which achieved synergistic effects to maximize lethality against microorganisms and minimize deterioration of produce quality. The review also identifies further research opportunities for the cost-effective commercialization of these technologies.     

果蔬中农药残留降解方法研究进展

随着食品安全问题日益受到重视,果蔬中的农药残留已成为世界各国的研究热点。目前国内外有关果蔬中农药残留降解方法的研究报道很多,本文全面综述了果蔬中农药残留降解的方法和技术,主要从物理、化学和生物降解3个方面阐述。其中物理方法主要包括洗涤、加工和储藏等;化学方法主要是指采用化学试剂、臭氧和光照等方法;而生物方法是利用生物酶破坏农药的结构或者利用基因工程将生物体内能降解农药的酶基因转移到载体基因中,从而降解农药。并对新降解技术如油茶素内酯降解法等进行了展望,以期为进一步研究提供参考和借鉴。     

鲜切果蔬精准保鲜包装技术的研究进展

鲜切果蔬因具有即食即用、方便营养及新鲜安全等特点受到广大消费者的青睐。但最小加工处理造成的机械损伤不利于鲜切果蔬品质的保持,限制了果蔬加工业的发展。因此,如何有效地保持品质、延长货架期是鲜切果蔬加工过程中需要解决的关键问题。而适当的精准包装可以改善鲜切果蔬周围环境、减少微生物数量,达到延长货架期和维持品质的作用。但不同种类的鲜切果蔬通常因其自身特点需要采用不同的包装技术。该文综述了鲜切果蔬分类及其适用包装技术的研究进展,系统分析了低温贮藏、气调包装、臭氧水处理、真空包装、超高压包装、可食性涂膜、纳米包装及微胶囊包装技术的保鲜原理及其在鲜切果蔬中的应用,旨在为今后鲜切果蔬包装技术的研究提供参考。     

A comprehensive review of intelligent packaging for fruits and vegetables: Target responders,classification, applications,and future challenges

Post-harvest fruits and vegetables are extremely susceptible to dramatic and accelerated quality deterioration deriving from their metabolism and adverse environmental influences. Given their vigorous physiological metabolism, monitoring means are lacking due to the extent that unnecessary waste and damage are caused. Numerous intelligent packaging studies have been hitherto carried out to investigate their potential for fruit and vegetable quality monitoring. This state-of-the-art overview begins with recent advances in target metabolites for intelligent packaging of fruits and vegetables. Subsequently, the mechanisms of action between metabolites and packaging materials are presented. In particular, the exact categorization and function of intelligent packaging of fruits and vegetables, are all extensively and comprehensively described. In addition, for the sake of further research in this field, the obstacles that impede the scaling up and commercialization of intelligent packaging for fruits and vegetables are also explored, to present valuable references.