The microbiology of minimally processed fresh fruits and vegetables

Minimally processed fresh (MPF) fruits and vegetables are good media for growth of microorganisms. They have been involved in outbreaks because of the consumption of products contaminated by pathogens. They are also sensitive to various spoilage microorganisms such as pectinolytic bacteria, saprophytic Gram‐negative bacteria, lactic acid bacteria, and yeasts. Contamination of MPF fruits and vegetables occurs at every stage of the food chain, from cultivation to processing. Polluted environments during cultivation or poor hygienic conditions in processing increase the risk of contamination with foodborne pathogens. Although MPF fruits and vegetables may harbor psychrotrophic microorganisms such as fluorescent pseudomonads or Listeria monocytogenes, good control of refrigeration temperature limits growth of spoilage and pathogenic microorganisms. Modified atmospheres are often efficient to maintain or improve visual and organoleptic quality of MPF fruits and vegetables, but their effects on microorganisms are inconsistent. Chemical disinfection can partially reduce the initial bacterial contamination; irradiation seems to be more efficient. The applications of legislations and quality assurance systems to control contamination, survival, and growth of foodborne pathogens in MPF fruits and vegetables are discussed.     

天津市2015~2019年生鲜果蔬病原微生物污染排查分析

为排查天津市即食生鲜果蔬病原微生物污染情况,2015~2019年在生产环节和流通环节抽取生菜、番茄、黄瓜、苦菊、桃和梨等6种即食果蔬品种共计654批次样品,采用国家标准方法分析样品中菌落总数、大肠菌群、沙门氏菌、金黄色葡萄球菌、单增李斯特氏菌、蜡样芽孢杆菌和大肠杆菌O157:H7污染状况进行风险分析。结果显示,654批次样品中检出食源性致病菌135批次,检出率为20.6%,其中包括沙门氏菌1份,金黄色葡萄球菌6份,蜡样芽孢杆菌128份,其他致病菌均未检出。食源性致病菌检出率较高的样品多出现在超市和农贸市场,表明即食果蔬致病菌的污染易发生在流通环节。即食生鲜果蔬中食源性致病菌污染对消费者健康存在潜在的安全隐患,需加强采后流通环节污染防控,保障即食果蔬食品安全,防止食源性疾病暴发。     

鲜切果蔬中生物保鲜剂的研究进展

随着人们对食品质量与安全的要求日益提高,鲜切果蔬保鲜技术迅速发展,生物保鲜剂因具有安全、高效等特点成为鲜切果蔬保鲜的研究热点。鲜切果蔬经分级、清洗、修整、去皮、切分、保鲜、包装等过程处理后,机械损伤、生理代谢、病原微生物污染等问题会引起鲜切果蔬腐烂、品质下降,给鲜活农产品的经济贸易带来了巨大损失,并对人类生命安全造成了重大威胁,因此本文综述了温度、气体环境、生理生化反应、微生物等几项能够导致鲜切果蔬褐变腐烂、品质下降的重要影响因素;总结了3种生物保鲜剂在鲜切果蔬保鲜中的应用,包括植物类天然保鲜剂、动物类天然保鲜剂和微生物保鲜剂;讨论了生物保鲜剂的不足,并对今后生物保鲜剂的发展进行了展望。     

Decontamination of Microorganisms and Pesticides from Fresh Fruits and Vegetables: A Comprehensive Review from Common Household Processes to Modern Techniques

Fresh fruits and vegetables are a rich source of micronutrients. However, many foodborne illnesses have been linked to the consumption of fresh fruits and vegetables as they are reported to harbor contaminants such as microorganisms and pesticides. Recently reported foodborne outbreaks have been linked to a diverse group of fruits and vegetables due to the presence of various pathogens including Salmonella, Escherichia coli, and Listeria monocytogenes. Also, the increased use of pesticides has resulted in the deposition of chemical residues on the surface of fruits and vegetables, which has led to the adverse health conditions such as cancer, birth defects, and neurodevelopmental disorders. Fresh commodities are subjected to various treatments to prevent or minimize these outbreaks, and the main targets of such treatments have been the elimination of pathogens and degradation of toxic chemical residues. Here, we have discussed various decontamination methods including simple household washing, chemical treatments, and modern technologies with their mode of action for microbial and pesticide removal. The simple household processes are not very effective in the removal of pathogenic organisms and pesticides. The use of modern techniques like cold plasma, ozone, high hydrostatic pressure, and so on, showed better efficacy in the removal of microorganisms and pesticides. However, their industrial use is limited considering high installation and maintenance cost. In this review, we suggest combined methods based on their mode of decontamination and suitability for a selected fruit or vegetable for effective decontamination of microbes and pesticide together to reduce the treatment cost and enhance food safety.     

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.     

Nutritional comparison of fresh,frozen, and canned fruits and vegetables II. Vitamin A and carotenoids,vitamin E,minerals and fiber

In this second part of our review, we examine the literature for changes in carotenoids, vitamin E, minerals, and fiber due to processing, storage, and cooking of fresh, frozen, and canned fruits and vegetables. While inconsistencies in methodology and reporting methods complicate interpretation of the data, the results show that these nutrients are generally similar in comparable fresh and processed products. The higher levels of carotenoids typically found in canned as compared to fresh products may be attributed to either reporting results on a wet rather than dry weight basis, greater extractability, or differences in cultivars. There are relatively few studies on processing, storage, and cooking effects on vitamin E in fruits and vegetables. Further research is needed to understand nutritional changes in those few fruits and vegetables rich in vitamin E, such as tomatoes. Minerals and fiber are generally stable to processing, storage, and cooking, but may be lost in peeling and other removal steps during processing. Mineral uptake (e.g., calcium) or addition (e.g., sodium) during processing can change the natural mineral composition of a product. Sodium concerns in canned food can be addressed by choosing products with no salt added. Since nutrient content varies considerably by commodity, cultivar, and postharvest treatments, inclusion of a wide variety of fruits and vegetables in the diet is encouraged. Copyright © 2007 Society of Chemical Industry     

Evaluation of chlorine dioxide gas residues on selected food produce

In recent years, the consumption of fresh fruits and vegetables has greatly increased, and so has its association with contamination of several foodborne pathogens (Listeria, Salmonella, and Escherichia coli). Hence, there is a need to investigate effective sanitizer systems for produce decontamination. Chlorine dioxide (ClO(2)), a strong oxidizing gas with broad spectrum and sanitizing properties, has previously been studied for use on selected fruits and vegetables. ClO(2) gas treatments show great potential for surface pathogen reduction; however its use from a residue safety standpoint has yet to be assessed. Thus, the objective of this study was to evaluate residues of ClO(2), chlorite, chlorate, and chloride on selected fresh produce surfaces after treatment with ClO(2) gas. A rinse procedure was used and water samples were analyzed by N, N-diethyl-p-phenylenediamine and ion chromatography method (300.0). Seven different foods--tomatoes, oranges, apples, strawberries, lettuce, alfalfa sprouts, and cantaloupe--were analyzed after ClO(2) treatment for surface residues. Very low residues were detectable for all the food products except lettuce and alfalfa sprouts, where the measured concentrations were significantly higher. Chlorine dioxide technology leaves minimal to no detectable chemical residues in several food products, thus result in no significant risks to consumers. Practical Application: Potential for chlorine dioxide gas treatments as an effective pathogen inactivation technology to produce with minimal risk for consumers.     

Green tea and grape seed extracts — Potential applications in food safety and quality

Using “natural green” plant extracts or their derived products in various food and beverage applications is an increasing trend in the food industry. Selection of these plant extracts and their application depends on their functional properties, availability, cost effectiveness, consumer awareness and their effect on the sensory attributes of the final product. Green tea extract (GTE) and grape seed extract (GSE) are two popular plant extracts that have been widely used in various food and beverage applications. Green tea is a widely consumed beverage that has attracted more attention in the recent years due to its health benefits like antioxidant, antimicrobial, anticarcinogenic and anti-inflammatory properties. Grape seed extract is derived from the grape seeds that is extracted, dried and purified to produce polyphenolic compounds-rich extract that also has well documented antioxidant, antimicrobial and anti-inflammatory properties. These two plant extracts (polyphenolic and proanthocyanidin rich compounds) have potential antioxidant properties by inhibiting the lipid oxidation and warmed over flavors and antimicrobial activities against major food borne pathogens like Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni in preventing pathogen contamination. Furthermore, they have demonstrated synergism in antimicrobial activity when used in combination with organic acids (malic, tartaric acid, benzoic acids etc.), bacteriocins like nisin or chelating agents like EDTA in various model systems including fresh produce (fruits and vegetables), raw and ready-to-eat meat and poultry products. Apart from beneficial effects of grape seed extract in food safety and quality, concerns regarding the side effects of GSE are also addressed. Nevertheless, persistent recalls of the food products involving foodborne pathogens despite various control measures calls for efficient bacteriostatic and bactericidal agents and technologies to deliver the active components for an effective inhibition of pathogens. Therefore, further research involving electrostatic spray and nanoscale delivery of the active components present in these natural, green, plant extracts and using them as a component in multiple hurdle approach would enhance the food safety and quality in addition to providing alternative “green” solutions to the food processors.     

Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables

Abstract

Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approach. Biological control refers to postharvest control of pathogens using microbial cultures. With respect to application of biological control for increasing the shelf-life of food, the term biopreservation is favored, although the approach is identical. The methods for screening and development of biocontrol agents differ greatly according to their intended application, but the efficacy of all current approaches following scale-up to commercial conditions is recognized as insufficient. The combination of biological and physical methods to maintain quality has the potential to overcome the limitations of current approaches. This review compares biocontrol and biopreservation approaches, alone and in combination with physical methods. The recent increase in the use of meta-omics approaches and other innovative technologies, has led to the emergence of new strategies to increase the shelf-life of fruit and vegetables, which are also discussed herein.     

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。     

Advances in Edible Coatings for Fresh Fruits and Vegetables: A Review

Edible coatings are an environmentally friendly technology that is applied on many products to control moisture transfer, gas exchange or oxidation processes. Edible coatings can provide an additional protective coating to produce and can also give the same effect as modified atmosphere storage in modifying internal gas composition. One major advantage of using edible films and coatings is that several active ingredients can be incorporated into the polymer matrix and consumed with the food, thus enhancing safety or even nutritional and sensory attributes. But, in some cases, edible coatings were not successful. The success of edible coatings for fresh products totally depends on the control of internal gas composition. Quality criteria for fruits and vegetables coated with edible films must be determined carefully and the quality parameters must be monitored throughout the storage period. Color change, firmness loss, ethanol fermentation, decay ratio and weight loss of edible film coated fruits need to be monitored. This review discusses the use of different edible coatings (polysaccharides, proteins, lipids and composite) as carriers of functional ingredients on fresh fruits and vegetables to maximize their quality and shelf life. This also includes the recent advances in the incorporation of antimicrobials, texture enhancers and nutraceuticals to improve quality and functionality of fresh-cut fruits. Sensory implications, regulatory status and future trends are also reviewed.     

Innovations in the Development and Application of Edible Coatings for Fresh and Minimally Processed Fruits and Vegetables

ABSTRACT: One of the major growth segments in the food retail industry is fresh and minimally processed fruits and vegetables. This new market trend has thus increased the demands to the food industry for seeking new strategies to increase storability and shelf life and to enhance microbial safety of fresh produce. The technology of edible coatings has been considered as one of the potential approaches for meeting this demand. Edible coatings from renewable sources, including lipids, polysaccharides, and proteins, can function as barriers to water vapor, gases, and other solutes and also as carriers of many functional ingredients, such as antimicrobial and antioxidant agents, thus enhancing quality and extending shelf life of fresh and minimally processed fruits and vegetables. This review discusses the rationale of using edible coatings on fresh and minimally processed produce, the challenges in developing effective coatings that meet the specific criteria of fruits and vegetables, the recent advances in the development of coating technology, the analytical techniques for measuring some important coating functionalities, and future research needs for supporting a broad range of commercial applications.     

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.     

Fruit and Vegetable Waste: Bioactive Compounds,Their Extraction,and Possible Utilization

Fruits and vegetables are the most utilized commodities among all horticultural crops. They are consumed raw, minimally processed, as well as processed, due to their nutrients and health‐promoting compounds. With the growing population and changing diet habits, the production and processing of horticultural crops, especially fruits and vegetables, have increased very significantly to fulfill the increasing demands. Significant losses and waste in the fresh and processing industries are becoming a serious nutritional, economical, and environmental problem. For example, the United Nations Food and Agriculture Organization (FAO) has estimated that losses and waste in fruits and vegetables are the highest among all types of foods, and may reach up to 60%. The processing operations of fruits and vegetables produce significant wastes of by‐products, which constitute about 25% to 30% of a whole commodity group. The waste is composed mainly of seed, skin, rind, and pomace, containing good sources of potentially valuable bioactive compounds, such as carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils, among others. These phytochemicals can be utilized in different industries including the food industry, for the development of functional or enriched foods, the health industry for medicines and pharmaceuticals, and the textile industry, among others. The use of waste for the production of various crucial bioactive components is an important step toward sustainable development. This review describes the types and nature of the waste that originates from fruits and vegetables, the bioactive components in the waste, their extraction techniques, and the potential utilization of the obtained bioactive compounds.     

Alfalfa seed germination and yield ratio and alfalfa sprout microbial keeping quality following irradiation of seeds and sprouts.

Foods can be treated with gamma radiation, a nonthermal food process, to inactivate foodborne pathogens and fungi, to kill insects on or in fruits and vegetables, and to increase shelf life. Gamma irradiation is especially well suited for these treatments because of its ability to penetrate commercial pallets of foods. Irradiated fruits, vegetables, poultry, and hamburger have been received favorably by the public and are now available in supermarkets. The use of irradiation on fresh alfalfa sprouts was studied to determine its effect on keeping quality as related to aerobic microbial load. After an irradiation dose of 2 kGy, the total aerobic count decreased from 10(5-8) to 10(3-5) CFU/g, and the total coliform counts decreased from 10(5-8) to 10(3-0) CFU/g. The results showed that the sprouts maintained their structure after irradiation, and the keeping quality was extended to 21 days, which is an increase of 10 days from the usual shelf life. The effect of various doses of irradiation on alfalfa seeds as measured by percent germination and yield ratio (wt/wt) of sprouts was determined. There was little effect on the percent germination, but as the dose increased, the yield ratio of alfalfa sprouts decreased. As the length of growing time increased, so did the yield ratio of the lower dose irradiated seeds (1 to 2 kGy). The irradiation process can be used to increase the shelf life of alfalfa sprouts, and irradiating alfalfa seeds at doses up to 2 kGy does not unacceptably decrease the yield ratio for production of alfalfa sprouts.     

Nonextractable polyphenols,usually ignored,are the major part of dietary polyphenols: A study on the Spanish diet

Scope: Dietary polyphenols (PP) can be divided into two groups: extractable polyphenols (EPP) or compounds solubilized by aqueous organic solvents, and nonextractable polyphenols (NEPP) or compounds that remain in their corresponding extraction residues. Most studies on food polyphenols and dietary intakes address exclusively EPP. The objective of this work was to determine the actual amount of PP, including NEPP, in food and in a whole diet. Methods and results: HPLC‐MS analyses were performed to identify EPP in methanol–acetone extracts and NEPP in the acidic hydrolyzates of their extraction residues in cereals, fruits, vegetables, nuts, and legumes. NEPP contents, estimated as hydrolyzable PP plus nonextractable proanthocyanidins (PA), ranged from 880 mg/100 g dry weight in fruits to 210 mg/100 g in cereals and were substantially higher than the contents of EPP. NEPP intake (day/person) in the Spanish diet (942 mg) is higher than EPP intake (258 mg) fruits and vegetables (746 mg) are the major contributors to the total PP intake (1201 mg). Conclusion: Non extractable polyphenols are the major part of dietary polyphenols. The knowledge of intakes and physiological properties of NEPP may be useful for a better understanding of the potential health effects of dietary PP.     

Worldwide Status of Fresh Fruits Irradiation and Concerns about Quality,Safety, and Consumer Acceptance

Development of knowledge-based food preservation techniques have been a major focus of researchers in providing safe and nutritious food. Food irradiation is one of the most thoroughly investigated food preservation techniques, which has been shown to be effective and safe through extensive research. This process involves exposing food to ionizing radiations in order to destroy microorganisms or insects that might be present on and/or in the food. In addition, the effects of irradiation on the enzymatic activity and improvement of functional properties in food have also been well established. In the present review, the potential of food irradiation technology to address major problems, such as short shelf life, high-initial microbial loads, insect pest management (quarantine treatment) in supply chain, and safe consumption of fresh fruits was described. With improved hygienic quality, other uses, such as delayed ripening and enhanced physical appearance by irradiation were also discussed. Available data showed that the irradiation of fruits at the optimum dose can be a safe and cost-effective method, resulting in enhanced shelf life and hygienic quality with the least amount of compromise on the various nutritional attributes, whereas the consumer acceptance of irradiated fruits is a matter of providing the proper scientific information.     

Pre-processed fruits as raw materials: part II—process conditions,demand and safety aspects

The demand for pre-processed fruits has grown rapidly in recent years as a result of consumer attention towards fresh, healthy and convenient foods. Most of the fruits are available seasonally and they are perishable, so it is necessary to have a continuous supply of the fruits to avoid the blockages in the fruit processing industry. The review is written in the purview of this issue, and it presents pre-processed fruits as a sustainable solution. The present review is part II of the series of articles on pre-processed fruits as the raw material for various food industries. The fruits covered here are mango, pineapple, pear, olive and papaya. The article continues to emphasise the critical processing and storage condition for these fruits ranked higher in terms of their production quantity and economic value. The fruits are critically reviewed for their processing, storage and safety aspects along with key research findings of different processing techniques. The important safety aspects associated with such processed commodities are also discussed.     

A multifaceted approach to harness probiotics as antagonists on plant based foods,for enhanced benefits to be reaped at a global level

Investigations into probiotics have focused on their health benefits thus far, with some of the findings finally reaching the food and pharmaceutical industries, which have used them for commercial purposes. In biocontrol research some microbes, mainly isolated from plants, have shown antagonism towards both enteric and plant pathogens, and some of them represent probiotic species. Fresh fruits and vegetables are regarded as health‐promoting dietary constituents, and if probiotics could be used to control the pathogens on them then they could turn out to be even healthier. The fresh produce industry still depends on agrochemicals and the increase in the demand for high‐priced organically grown produce indicates consumer concerns regarding the use of agrochemicals. If the potential of probiotic organisms to serve as biocontrol agents for fresh produce is exploited, all fresh produce can be made as safe as organically grown produce, and much more wholesome. This review appraises the feasibility of such a move by evaluating how research has progressed in both disciplines (probiotic and biocontrol) and suggests sharing results from research via information technology, efficient collaboration, and the use of novel molecular biological tools to achieve the objective of probiotic antagonists. © 2018 Society of Chemical Industry     

Status of Bioactive Compounds in Foods,with Focus on Fruits and Vegetables

Components of cereals, legumes, pulses, proteins, sea food, milk, carbohydrates and lipids are being evaluated for their influence on human health, as biofunctional compounds. However, references dealing with fruits and vegetables exceed any other food group and accordingly their focus. Fruits and vegetables abound in a spectacular range of such health influencing compounds and thus, study of their bioactivity, in lieu of their consumption in fresh or processed form. Anti-cancerous phenolics from Phyllanthus, radioprotective Litchi phenolics/flavonoids, hypoglycemic Sygium, quercitin and hydroxyl cinnamates of Sweet cherries, xanthones of Mangosteen, ellagitannins of Pomegranate, ursolic acid of Sea buckthorn, muscle relaxative watermelon, anti-cholesterolemic soluble fibre and sterols, cardioprotective saponins, ACE-inhibitory potato hydrolysates, anti-pancreatic cancerous ascorbic acid, carotenoids including pro-vitamin A are few examples unraveled. Thus, the imminent scope to obviate their structural chemistry, influence on storage and processing conditions, factors favoring their bio-accessibility/bio-availability in the food formulations, influencing human health. It is the meticulous combination of these compounds in daily consumption that determines their usefulness to human body. What is of paramount importance is the actual health benefits accrued from consumption of such functional- compound based fresh/processed fruits,vegetables or other foods.