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。     

Evaluation of pesticide residues in fruits and vegetables from Algeria

ABSTRACT

A total of 160 samples of 13 types of fresh fruits and vegetables from domestic production and import were analysed to detect the presence of pesticide residues. Analysis was performed by multi-residual extraction followed by gas chromatography–mass spectrometry. In 42.5% of the tested samples, no residues were found and 12.5% of samples contained pesticide residues above maximum residue limits. Risk assessment for long-term exposure was done for all pesticides detected in this study. Except chlorpyrifos and lambda-cyhalothrin, exposure to pesticides from vegetables and fruits was below 1% of the acceptable daily intake. Short-term exposure assessment revealed that in seven pesticide/commodity combinations, including three pesticides (chlorpyrifos, deltamethrin and lambda-cyhalothrin), the acute reference dose had been exceeded.     

Juice extraction from apples and other fruits and vegetables

Presses are the usual and traditional method of removing juice from fruit and vegetable materials. However, recently diffusion extraction, centrifugation, and specialized ultrafiltration techniques have been explored and have been exploited commercially to a limited extent. Yield efficiency diagrams that relate juice yields to mash feed rates provide a mechanism for comparing presses and other processes such as enzyme treatments or decanter centrifuges for efficiency under a stated set of circumstances. Diffusion extraction is capable of removing 90 to 94% of soluble solids from properly prepared apple slices, but the resulting juice is diluted with extraction water and is high in extracted tannins. Concentration is necessary to obtain juice solids equivalency, and the resulting juice has sour/astringent flavors that must be removed with tannin absorbants to provide acceptable flavor. Currently, decanter centifuges are used commercially and have provided an alternative to presses under certain circumstances. When naturally colored and flavored (unoxidized) juices are desired, the decanter provides a useful alternative to presses because it is easily inert gas blanketed. Utilization of a metallic ultrafilter as a press has been patented but has not achieved commercial utilization. The technical literature describing the application of these juice extraction juices, primarily to apples, is reviewed extensively.     

果蔬中硒形态的研究进展

硒是人体必需微量元素之一,人体缺乏硒元素或补充过量皆可导致多种疾病。我国绝大部分地区的居民缺硒,使用不同的方法将硒添加到果蔬中,可以提高果蔬的附加价值与经济效益,也使得硒在日常饮食中得到适当的补充。因此,果蔬富硒研究是一项利于全民健康的、具有重大意义的课题研究。本篇文章为一个简短的综述,主要内容是富硒果蔬近十年来的研究现状,同时讨论了果蔬中硒的富集方法及检测过程中的分析方法。      

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。     

Content of fluorine in vegetables and fruits from an industrial area

Content of fluorine in vegetables and fruits from allotments situated in an industrial area as well as in an agricultural area without industrial emissions was determined. The fluorine determination was made by means of a potentiometric method with application of an ion-selective electrode. Statistically significant differences between the fluorine content in vegetables and fruits from an area contaminated with the emissions of fluorine compounds and the fluorine content in vegetables and fruits from the control area were found. Significant differences between the fluorine content in above- and under-ground parts of some vegetables were stated. The greatest fluorine content appeared in parsley haulm and in black currants.     

Flavor quality of fruits and vegetables

Fruits and vegetables are important sources of vitamins, minerals, dietary fiber, and antioxidants. The relative contribution of each commodity to human health and wellness depends upon its nutritive value and per capita consumption; the latter is greatly influenced by consumer preferences and degree of satisfaction from eating the fruit or vegetable. Flavor quality of fruits and vegetables is influenced by genetic, preharvest, harvesting, and postharvest factors. The longer the time between harvest and eating, the greater the losses of characteristic flavor (taste and aroma) and the development of off‐flavors in most fruits and vegetables. Postharvest life based on flavor and nutritional quality is shorter than that based on appearance and textural quality. Thus, it is essential that good flavor quality be emphasized in the future by selecting the best‐tasting genotypes to produce, by using an integrated crop management system and harvesting at the maturity or ripeness stage that will optimize eating quality at the time of consumption, and by using the postharvest handling procedures that will maintain optimal flavor and nutritional quality of fruits and vegetables between harvest and consumption. Copyright © 2008 Society of Chemical Industry     

Chilling injury of fruits and vegetables

Abstract

Chilling injury affects many fruits and vegetables. Most crops of tropical and subtropical origin are sensitive to chilling injury. Some crops of Temperate Zone origin are also susceptible. These crops are injured by low, but nonfreezing, temperatures. At these temperatures, the tissues weaken because they are unable to carry on normal metabolic processes. Various physiological and biochemical alterations occur in the sensitive species in response to low‐temperature exposure. These alterations lead to the development of a variety of chilling injury symptoms, such as surface pitting, discoloration, internal breakdown, failure to ripen, growth inhibition, wilting, loss of flavor, and decay. This review article describes the changes in membrane lipids, permeability, proteins, carbohydrates, energy supply, respiration, ethylene production, and other metabolic processes that are affected by chilling temperatures. Methods for alleviation of chilling injury‐such as temperature preconditioning, intermittent warming, chemical treatments, hormonal regulation, controlled atmosphere storage, genetic manipulation, and other methods—are also discussed.     

壳聚糖在果蔬涂膜保鲜的应用

壳聚糖是从海洋生物虾、蟹的外壳中提取的甲壳素脱乙酰基得到,是迄今为止发现的唯一的阳离子动物纤维和碱性多糖。且壳聚糖在2013年经美国食品药物管理局批准(USFDA)称为"普遍认可的安全"(GRAS)食品添加剂。作为食品添加剂,壳聚糖有增稠剂、被膜剂、澄清剂抗氧化剂、风味改良剂、乳化剂等用途。其中,壳聚糖作为被膜剂应用于果蔬保鲜引起了消费者和研究员的广泛关注。其主要原因是壳聚糖具有较好的成膜性,能在水果表面形成一种半透膜,可以用来调节果蔬的内部环境,从而达到延缓果蔬呼吸速率,减少重量损失,保持果蔬整体质量,延长保质期等目的。本综述的主要目的是总结壳聚糖作为被膜剂,保护果蔬产品整体产品质量相关研究进展,为其发展指明了一定的方向。     

Carotenoids in traditional Portuguese fruits and vegetables

Carotenoids, α-carotene, β-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin, were determined in 10 varieties of five fruit species (orange, pear, peach, apple and cherry) and five varieties of four species of vegetables (Portuguese coles, turnip greens, purslane, leaf beet and beetroot leaves) cultivated in Portugal and country traditional, the fruits being of protected designation of origin or of protected geographical indication. The determination was done by high performance liquid chromatography, using two metal free reverse phase columns, an organic mobile phase based on acetonitrile, methanol and dichloromethane and a UV–vis photodiode array detector. Identification was done by retention time and spectral analysis and quantification was based on peak area at 450 nm by external calibration. The analysed leafy vegetables are a very good source of lutein (0.52–7.2 mg/100 g) and β-carotene (0.46–6.4 mg/100 g) while the analysed fruits have a considerably lower content of carotenoids (lutein, 0.0032–0.16 mg/100 g and β-carotene, 0.010–0.17 mg/100 g) and a complex and variable qualitative and quantitative carotenoid composition. Most estimated relative measurement expanded uncertainties were between 0.10 and 0.31. Results indicate that the carotenoid content of the analysed items could vary with species, varieties, geographical place of production (region, site) and time of harvest, and should be addressed in the eventual production of data for food composition data bases.     

纳米技术在采后果蔬保鲜中的研究进展

果蔬为人类提供多种营养素,如维生素、矿物质和生物活性物质等,但新鲜果蔬采后易腐烂变质,造成了很大的经济损失。采后贮藏技术如纳米技术可以有效地延缓采后水果的品质变化,就纳米技术在采后果蔬保鲜中的研究进展进行了综述。概述了纳米包装材料、纳米涂膜保鲜剂在采后果蔬保鲜中的开发与应用,纳米技术在果蔬中大分子物质纳米表征中的应用,以及纳米技术在采后果蔬致病菌检测方面的应用。纳米技术在采后果蔬保鲜领域中具有广阔的发展前景。     

Discoloration in raw and processed fruits and vegetables

Discoloration in fruits and vegetables is reviewed in relation to the chemical and biochemical causes of black, brown, red, yellow, and green discolorations. In raw materials, only a limited understanding has so far been achieved of the internal black and brown discolorations. The biochemical signaling pathways triggered by wounding or chilling-storage, the nature of the enzymes and reactive oxygen species involved, and the identity of the phenolic compounds oxidized are areas where further information is desirable. In processed materials, a greater comprehension is needed of the role of ascorbic acid reactions in the browning of fruits and "pinking" of Brassicaceous vegetables, and more information is desirable on the structure and properties of the discoloring pigments in many products. It is concluded that a greater knowledge of these areas, and of the naturally-occurring constituents that can accelerate or inhibit the causative reactions, would lead to the development of more efficient methods of controlling fruit and vegetable discolorations.     

Free carboxyl groups in wood

Ohne Zusammenfassung     

Modified atmosphere packaging of fruits and vegetables

Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.     

切割果蔬保鲜

切割果蔬是指果蔬经清洗、去皮、切割或切片、修整、包装而成的新鲜、方便、营养、无公害的果蔬产品 ,切割果蔬相对于未加工的果蔬由于受到机械损伤而更易腐败变质。从切割果蔬的组织生理、微生物、包装及品质等方面对切割果蔬进行了介绍。     

Plant sterols in vegetables,fruits and berries

The plant sterol contents of the most important vegetables, fruits and berries available in Finland were determined by capillary gas chromatography. The sample preparation procedure included both acid and alkaline hydrolysis to liberate sterols from their conjugates. The plant sterol contents of fresh vegetables ranged from 51 to 370 mg kg^?1 fresh weight (fw) in samples obtained from retail sale. The highest contents (>300 mg kg^?1) were measured in broccoli, Brussels sprouts, cauliflower and dill and the lowest (51 mg kg^?1) in potato. The range of sterol contents on a dry weight (dw) basis was high, 246–4100 mg kg^?1 dw. Considerable variation was also observed when individual samples of some vegetables were compared. Sitosterol was the main sterol (proportion 43–86%) in all vegetables except cucumber and spinach, in which Δ⁷‐sterols dominated. The total sterol contents were in the range 116–228 mg kg^?1 fw in all fresh fruits except avocado, which contained more sterols, 752 mg kg^?1 fw. In fresh berries the corresponding range was 60–279 m kg^?1 fw. The wild berries lingonberry and blueberry were better plant sterol sources than the cultivated berries blackcurrant, redcurrant and strawberry. In fruits and berries the proportion of sitosterol ranged from 61–93% total sterols. On the basis of the results, the contribution of vegetables, fruits and berries to the total average daily plant sterol intake was estimated to be ca 60 mg. © 2003 Society of Chemical Industry