水产品储运过程中的防腐保鲜

我国养殖水产的产量超过了捕捞产量,因养殖水产起捕比较集中,且鱼体易腐败变质,在储运过程中经常发生腐败变质现象,从而造成重大的经济损失。微生物的生长繁殖是导致鱼体腐败变质的主要原因,为减少储运过程中鱼体的腐败变质,需要采用一定防腐保鲜措施抑制微生物的生长繁殖。本文简要地介绍了鱼体储运过程中防腐保鲜方法：低温保鲜、气调保鲜、防腐剂保鲜、栅栏技术保鲜。     

Production of Shelf-Stable Ranch Dressing Using High-Pressure Processing

ABSTRACT:  High-pressure processing (HPP) can reduce or eliminate microorganisms of concern in food without deteriorating product quality; however, quality benefits must justify the substantial capital investment for the utilization of this technology. HPP is particularly a beneficial preservation technology for products damaged by thermal treatments or when product quality could be improved by reformulation to raise pH or eliminate chemical preservatives. The primary objectives of this study were to determine the efficacy of HPP to protect premium ranch dressing (pH 4.4) from microbial spoilage and to assess changes in physical, chemical, and sensory attributes throughout the product's shelf life. In inoculated-packages studies, the efficacy of HPP was measured against ranch dressing spoilage organisms: Pediococcus acidilactici, Lactobacillus brevis, and Torulaspora delbrueckii . HPP treatment (600 MPa, 3 min) decreased population of P. acidilactici , the most pressure-resistant spoilage organism tested, by ≥ 6.4 log CFU/g. During a shelf-life study of edible product, treating ranch dressing at 600 MPa for 5 min effectively prevented microbial spoilage throughout the storage period (26 wk at 4 and 26 °C). The pH and emulsion stability of ranch dressing were not adversely influenced by HPP. Extended storage of HPP product for 16 to 26 wk at 26 °C resulted in a decrease in consumer acceptance and significant changes in color and organic acid profile (specifically, increased pyroglutamic acid). These changes were consistent with those expected during extended storage of commercially available products. HPP may be used to produce premium ranch dressing, with defined shelf-life and storage conditions, without significantly changing product attributes.     

Self-preserving cosmetics

Preservatives are added to products for two reasons: first, to prevent microbial spoilage and therefore to prolong the shelf life of the product; second, to protect the consumer from a potential infection. Although chemical preservatives prevent microbial growth, their safety is questioned by a growing segment of consumers. Therefore, there is a considerable interest in the development of preservative-free or self-preserving cosmetics. In these formulations traditional/chemical preservatives have been replaced by other cosmetic ingredients with antimicrobial properties that are not legislated as preservatives according to the Annex VI of the Commission Directive 76/768/EEC and the amending directives (2003/15/EC, 2007/17/EC and 2007/22/EC). 'Hurdle Technology', a technology that has been used for the control of product safety in the food industry since 1970s, has also been applied for the production of self-preserving cosmetics. 'Hurdle Technology' is a term used to describe the intelligent combination of different preservation factors or hurdles to deteriorate the growth of microorganisms. Adherence to current good manufacturing practice, appropriate packaging, careful choice of the form of the emulsion, low water activity and low or high pH values are significant variables for the control of microbial growth in cosmetic formulations. This paper describes the application of the basic principles of 'Hurdle Technology' in the production of self-preserving cosmetics. Multifunctional antimicrobial ingredients and plant-derived essential oils and extracts that are used as alternative or natural preservatives and are not listed in Annex VI of the Cosmetic Directive are also reported.     

茶多酚-壳聚糖复合液对虹鳟鱼肉贮藏品质和菌群结构的影响

针对虹鳟鱼在贮藏过程中易受到微生物的污染而发生腐败变质的问题,将3 g/L茶多酚和10 g/L壳聚糖混合制成复配保鲜剂,浸泡涂膜覆盖于虹鳟鱼表面。以感官评价、挥发性盐基氮含量、菌落总数及菌群结构等为指标,研究保鲜剂对4℃贮藏虹鳟鱼肉贮藏品质变化的影响。结果表明:茶多酚和壳聚糖单独使用或复合使用均能延缓腐败的发生;复配保鲜剂能将4℃贮藏虹鳟鱼的货架期从8 d延长至13 d,效果优于单独使用;未经处理的新鲜虹鳟鱼片菌群由16个菌属组成,腐败末期则以假单胞菌属为优势菌属,而复合保鲜剂涂膜会明显抑制假单胞菌属的生长,进而减缓鱼肉品质劣变。综上,茶多酚和壳聚糖的复配保鲜剂有助于通过抑制优势腐败菌的生长延缓4℃贮藏条件下虹鳟鱼的腐败变质。     

Spoilage microbiota associated to the storage of raw meat in different conditions

The spoilage of raw meat is mainly due to undesired microbial development in meat during storage. The type of bacteria and their loads depend on the initial meat contamination and on the specific storage conditions that can influence the development of different spoilage-related microbial populations thus affecting the type and rate of the spoilage process. This review focuses on the composition of raw meat spoilage microbiota and the influence of storage conditions such as temperature, packaging atmosphere and use of different preservatives on the bacterial diversity developing in raw meat. In addition, the most recent tools used for the detection and identification of meat microbiota are also reviewed.     

Selection and Use of Postharvest Technologies as a Component of the Food Chain

ABSTRACT: Postharvest technologies refer to the stabilization and storage of unprocessed or minimally processed foods from the time of harvest until final preparation for human consumption. There is a special emphasis on seasonal crops, and simple, labor-intensive, capital-sparing technologies suitable for developing countries where food spoilage rates are high and malnutrition is prevalent. The first step is to determine the major spoilage vectors for each type of food and then identify a technology that will control that vector. For cereal grains the major spoilage vectors are mold, insects, rodents, and other vertebrate pests. Mold is controlled by prompt and adequate drying to a water activity below 0.7. Insects are controlled by good housekeeping, and use of insecticides and fumigants. Rodents are controlled by baits, traps, fumigants, and rodent-proof storage structures. For fruits, vegetables, roots, and tubers the main spoilage vectors are bruising, rotting, senescence, and wilting. Bruising is avoided by careful handling and use of shock-resistant packaging. Rotting is controlled by good housekeeping, gentle handling to avoid breaking the skin, cool storage, and use of preservatives. Senescence is retarded by cold storage or controlled-atmosphere storage. Wilting is controlled by high humidity and cold storage. Growth of microbes is the major spoilage of fish and other foods of animal origin. This is controlled by refrigerated or frozen storage, drying, freezing, or canning. Most spoilage vectors accelerate as the temperature and humidity increase; this makes it more difficult to control spoilage in tropical than in temperate regions.     

酱油变质微生物因素及乳酸菌在防腐中的应用

酱油是经微生物发酵制成的具有独特色、香、味的液体调味品。酱油中含有充足的营养物质,并且酱油发酵体系多为混菌体系,因此在酱油发酵、生产和贮藏过程中容易因污染腐败菌出现“生花”、变馊、胀袋、沉淀、浑浊等现象,导致酱油的腐败变质。该文详细阐述了酱油中存在的腐败微生物种类和由它们引起的酱油变质现象,以及通过发酵工艺优化、添加防腐剂和生物技术等手段防止酱油腐败的相应措施。最后概述了乳酸菌的抗菌代谢产物种类与抑菌特性,并讨论了乳酸菌在酱油防腐中的应用潜力,以期为开发保障酱油品质稳定和提升的方法提供经验和参考。     

天然防腐剂在鲜切水果和果汁保鲜中的研究进展

随着国民生活水平的提高,人们对低热量食品的需求不断增大,即食鲜切水果和果汁的消费也逐渐增加,它们的安全性越来越受到人们的重视。鲜切水果和果汁由于组织和形态被破坏极易受到病原微生物和腐败微生物的污染,如果加工或储存条件不当,极易造成微生物致病和腐败。微生物学、酶学、化学或物理学变化均能引起鲜切水果与未高温消毒果汁的质量损失。其中,微生物造成的损失非常重要,有两方面原因:一是微生物毒素或病原微生物对消费者的健康构成威胁,二是微生物腐败给消费者造成经济损失。使用防腐剂可以有效减少微生物污染增强安全性。天然防腐剂既能保证食品安全又能保持品质特征,近年来,将其用于鲜切水果与未高温消毒果汁以防止微生物腐败方面的研究备受关注。本文综述了来自动物、植物和微生物的天然防腐剂对鲜切水果和果汁中病原微生物及腐败微生物的抑菌作用。     

Post-harvest control strategies: minimizing mycotoxins in the food chain

Contamination of cereal commodities by moulds and mycotoxins results in dry matter, quality, and nutritional losses and represents a significant hazard to the food chain. Most grain is harvested, dried and then stored on farm or in silos for medium/long term storage. Cereal quality is influenced by a range of interacting abiotic and biotic factors. In the so-called stored grain ecosystem, factors include grain and contaminant mould respiration, insect pests, rodents and the key environmental factors of temperature, water availability and intergranular gas composition, and preservatives which are added to conserve moist grain for animal feed. Thus knowledge of the key critical control points during harvesting, drying and storage stages in the cereal production chain are essential in developing effective prevention strategies post-harvest. Studies show that very small amounts of dry matter loss due to mould activity can be tolerated. With <0.5% dry matter loss visible moulding, mycotoxin contamination and downgrading of lots can occur. The key mycotoxigenic moulds in partially dried grain are Penicillium verrucosum (ochratoxin) in damp cool climates of Northern Europe, and Aspergillus flavus (aflatoxins), A. ochraceus (ochratoxin) and some Fusarium species (fumonisins, trichothecenes) on temperate and tropical cereals. Studies on the ecology of these species has resulted in modelling of germination, growth and mycotoxin minima and prediction of fungal contamination levels which may lead to mycotoxin contamination above the tolerable legislative limits (e.g. for ochratoxin). The effect of modified atmospheres and fumigation with sulphur dioxide and ammonia have been attempted to try and control mould spoilage in storage. Elevated CO2 of >75% are required to ensure that growth of mycotoxigenic moulds does not occur in partially dried grain. Sometimes, preservatives based on aliphatic acids have been used to prevent spoilage and mycotoxin contamination of stored commodities, especially feed. These are predominantly fungistats and attempts have been made to use alternatives such as essential oils and anti-oxidants to prevent growth and mycotoxin accumulation in partially dried grain. Interactions between spoilage and mycotoxigenic fungi and insect pests inevitably occurs in stored grain ecosystems and this can further influence contamination with mycotoxins. Effective post-harvest management of stored commodities requires clear monitoring criteria and effective implementation in relation to abiotic and biotic factors, hygiene and monitoring to ensure that mycotoxin contamination is minimised and that stored grain can proceed through the food chain for processing.     

果蔬微生物保鲜技术的研究进展

果蔬保鲜技术的发展,具有显著的经济和社会效益。然而随着人们对食品安全的普遍关注,果蔬保鲜产业也有了天然、安全和营养的新要求。微生物保鲜是一种安全、无毒、有效的生物保鲜技术,应用前景广阔。采用拮抗菌制剂对果蔬进行保鲜可以减少化学合成杀菌剂对人类健康的不良影响,并有效防止植物病原菌的抗药性。综述了用于果蔬保鲜的微生物种类、保鲜机理及处理方法,对果蔬微生物保鲜研究作了简单概述,对目前存在的问题和发展趋势进行了分析,以期为安全有效的果蔬微生物保鲜剂的开发提供参考。     

Calorimetric Examination of Cut Fresh Pineapple Metabolism

Isothermal microcalorimetric analysis of cut fresh pineapple was used to examine metabolic events occurring in the fruit under different storage conditions. The results define conditions most suited for cut pineapple storage. The baseline heat production for pineapple tissue is quite low (0.2 μW per mg wet weight). During storage, heat producing metabolic reactions develop which cause spoilage of the fruit. The time course of heat production during storage is affected by changes in atmosphere and by chemical treatments. Effects of inhibitor and antibiotic additions indicate that most of the heat production associated with spoilage is related to the growth of microbial flora.     

Integrated management of the risks of stored grain spoilage by seedborne fungi and contamination by storage mould mycotoxins – An update

Fungal spoilage of stored grains may occur when activity of water (aw) in cereal grain exceeds a critical limit enabling mould growth. Because it is not feasible to maintain all parts of large grain bulks below this critical moisture limit during prolonged storage time, an infection by seed-borne fungi is not rare in cereal grain stored under humid temperate or hot climates, inducing irreversible qualitative losses. Additionally, some fungal species produce harmful mycotoxins. The most harmful toxigenic species belong to the group of xerophilic species (genera Aspergillus and Penicillium). Because mycotoxin contamination of cereal grain is a worldwide issue for public health and a permanent concern for cereal-food industries facing the challenge of a permanent monitoring mycotoxin content in their primary matters, tolerable levels of mycotoxins are severely regulated worldwide. Mycotoxin-producing species growth is closely dependent of grain moisture levels enabling biological activity in grain ecosystem. Consequently, mould growth in stored grain bulks can be anticipated through early detection of grain and mould respiration. The prevention of mycotoxigenic fungi spoilage of stored grain can be managed by a preventive strategy. The main objective of the review was to describe the different methods, material and practices combined in such an integrated preventive approach. Some solutions potentially acceptable for the decontamination of moderately contaminated grain are also discussed.Integrated management of mould spoilage risks in stored grain is based on five pillars: i/Prevention of mould development by keeping grain moisture below the critical limit of fungal growth; ii/Accurate monitoring of grain aw and temperature changes during the storage period, associated to the monitoring of early indicators of respiration activity of storage fungi; iii/Reduction of grain bulk moistening trends by physical intervention means; iv/Use of physical treatments (ozone, grain peeling or abrasion) to limit mycotoxin contamination transfer to processed cereal products; v/Possible use of bio-competitive strains of fungi or bacteria to prevent the development of mycotoxigenic fungi in grain bulks. The future research needs on this topic are also evocated.     

粮食真菌毒素污染的预防与脱毒

粮食真菌毒素的预防包括预防粮食作物田间生长及收获后储藏过程中毒素的生物合成及代谢。真菌毒素的脱毒主要指除去、破坏及减少毒素作用的收获后处理。田间及储藏中没能有效控制真菌毒素的合成必将导致对人类健康的危害及经济损失，而有效的监控将避免真菌毒素成为威胁人类健康的污染源。应用综合预防措施将是控制真菌毒素的有效策略。本文强调的收获前后措施将依特别年份的特定的气候条件而定。弄清适于真菌污染、生长和产毒环境因素是有效控制食物及饲料中真菌毒素的关键措施。有很多新的有效的收获前预防策略正在开发，如利用转基因技术创造粮食作物抗性新品种及利用非产毒真菌菌株生物防治等。收获后的防止真菌毒素产生主要依赖于收获前后的良好的管理措施。脱毒策略可分为物理、化学或微生物脱毒技术，这些脱毒技术主要通过破坏、修饰或吸附真菌毒素，从而达到减少或消除毒素作用。     

Strategies to reduce mycotoxin levels in maize during storage: a review

Maize (Zea mays L.) is one of the main cereals as a source of food, forage and processed products for industry. World production is around 790 million tonnes of maize because as a staple food it provides more than one-third of the calories and proteins in some countries. Stored maize is a man-made ecosystem in which quality and nutritive changes occur because of interactions between physical, chemical and biological factors. Fungal spoilage and mycotoxin contamination are of major concern. Aspergillus and Fusarium species can infect maize pre-harvest, and mycotoxin contamination can increase if storage conditions are poorly managed. Prevention strategies to reduce the impact of mycotoxin in maize food and feed chains are based on using a hazard analysis critical control point systems (HACCP) approach. To reduce or prevent production of mycotoxins, drying should take place soon after harvest and as rapidly as feasible. The critical water content for safe storage corresponds to a water activity (a _w) of about 0.7. Problems in maintaining an adequately low a _w often occur in the tropics where high ambient humidity make the control of commodity moisture difficult. Damage grain is more prone to fungal invasion and, therefore, mycotoxin contamination. It is important to avoid damage before and during drying, and during storage. Drying maize on the cob before shelling is a very good practice. In storage, many insect species attack grain and the moisture that can accumulate from their activities provides ideal conditions for fungal activity. To avoid moisture and fungal contamination, it is essential that the numbers of insects in stored maize should be kept to a minimum. It is possible to control fungal growth in stored commodities by controlled atmospheres, preservatives or natural inhibitors. Studies using antioxidants, essential oils under different conditions of a _w, and temperature and controlled atmospheres have been evaluated as possible strategies for the reduction of fungal growth and mycotoxin (aflatoxins and fumonisins) in stored maize, but the cost of these treatments is likely to remain prohibitive for large-scale use.     

Hyperbaric storage at room temperature: Effect of pressure level and storage time on the natural microbiota of strawberry juice

Hyperbaric storage at room temperature (HS-RT) has recently been proposed as a potential alternative to refrigeration for food preservation. However, there are still very few data about the effects of HS-RT conditions on food microbiota during and after storage. To estimate the effect of pressure level and storage time, we stored strawberry juices at 20 °C and 0.1, 25, 50, 100, and 200 MPa for 1, 10, or 15 days. Total aerobic mesophiles, lactic acid bacteria, and yeasts and molds were quantified before and immediately after storage as well as after a 3-day recovery period at atmospheric pressure and at 20 °C. Both pressure level and storage time affected microbial growth during and after HS-RT. In strawberry juice, storage at 25 MPa retarded microbial growth, but total growth inhibition could not be guaranteed, especially for long storage times. Storage pressures of at least 50 MPa were needed to reduce the initial microbial load during storage. After HS-RT at 25 or 50 MPa, microorganisms could quickly recover their cell-proliferating capacity and, therefore, larger pressures are required to increase microbial stability after decompression.Industrial relevanceHyperbaric storage at room temperature (HS-RT) involves very low energy consumption and, therefore, it can provide an interesting opportunity to reduce energy costs during food storage in comparison with other preservation methods such as freezing or refrigeration. HS-RT could be employed in a wide variety of scenarios: food industry, ship or truck transport for long distances, school or hospital kitchens, restaurants, or even at home. Moreover, its application in developing countries, in which the continuous supply of electric energy is difficult, would be especially noteworthy. However, before industrial implementation, much more research is needed to clarify the effects of the storage conditions on the agents that cause food deterioration (mainly microorganisms and enzymes). The current study contributes to increasing this knowledge.     

鲜湿米粉贮藏过程中品质变化的考察

桂林米粉属于鲜湿米粉,由于其水分含量高、易受微生物污染而不易保存,因此分析其腐败菌及筛选抑菌剂对延长其货架期、保持其口感与营养价值十分重要。为了研究桂林米粉贮藏过程中微生物生长情况,本文从室温贮藏1~3 d的桂林米粉中分离纯化得到13株腐败菌,再通过反证试验得到6株主要腐败菌MF1、MF2、MF3、MF4、MF6和MF12,通过常规鉴定结合分子鉴定确定桂林米粉的主要腐败菌为苏云金芽孢杆菌（Bacillus thuringiensis）、蜡样芽孢杆菌（Bacillus cereus）、贝莱斯芽孢杆菌（Bacillus velezensis）、柠檬酸杆菌属（Citrobacter sp.）和乙酰微小杆菌（Exiguobacterium acetylicum）。通过平板培养从五种食品添加剂中筛选有效抑菌剂及最适抑菌浓度,结果表明,不同浓度的抗坏血酸和柠檬酸对6种腐败细菌均有良好的抑菌效果,最适抑菌浓度分别为90和120 mg/mL。这说明抗坏血酸和柠檬酸可作为桂林米粉的防腐剂,在桂林米粉贮藏保鲜上有一定的应用前景。

     

Application of biopreservatives in meat preservation: a review

As a highly perishable food, raw meat, if not preserved, will spoil due to the altered metabolism, microbial activity and external factors during storage. Biopreservatives, as a new type of preservatives, are characterised by nontoxicity, extensive source and good application prospects in the raw meat. This review discusses the factors responsible for the spoilage of raw meat, recaps the spoilage bacteria in the raw meat and summarises the major antibacterial mechanism of various biopreservatives. Moreover, application of various biopreservatives in the preservation of raw meat is emphatically reviewed. In addition, some existing challenges for application of biopreservatives and their prospective development are also discussed. The present work provides a theoretical reference for application of various biopreservatives in different types of raw meat for shelf life extension.     

冷却肉微生物腐败与冷链系统

冷却肉极易发生微生物腐败,温度是最关键的影响因素。冷链系统持续的低温能抑制微生物的生长繁殖,预防冷却肉腐败。本文简述了微生物代谢活动对冷却肉腐败的影响,重点将冷链系统分为加工冷链、运输冷链、销售冷链和家庭保藏四部分,分别从概念及存在的问题等方面加以阐述,并展望了其未来有待提高完善的地方。     

Application of microbial TTIs as smart label for food quality: Response mechanism,application and research trends

BackgroundCompared to other available non-microbial TTIs, the distinct advantage of microbial TTI is that its response (color change) is a result of a process (the growth and metabolic activity of the TTI microorganism) simulating the actual quality loss process (the bacterial growth and metabolism of the “specific spoilage organisms”) of many foods, especially most chilled high-protein foods. This indicates a high possibility that food quality changes due to microorganisms could be reflected by microbial TTIs accurately.Scope and approachThe components of microbial TTIs, response and prediction mechanism are described. The application modeling methods, applications, benefits and limitations, research trends of microbial TTIs are systematically summarized and discussed.Key findings and conclusionsThe article puts forward five development trends of microbial TTIs: The microbial TTIs with microencapsulation of microorganisms and two separate compartments could keep microorganisms stable and allow for room temperature storage; The TTIs integrated with RFID and bar code technologies could identify and transmit the color message of TTIs automatically and systematically; The microbial TTIs could be fabricated by a simplified method; The sensitive TTIs to different microbial metabolites are valuable complementarity for microbial TTIs application; The available open shared TTI kinetic parameters database and shelf life prediction models could facilitate the microbial TTIs application.