Microbiological Quality and Safety of Fresh Fruits and Vegetables at Retail Levels in Korea

The aim of this study was to evaluate the microbiological quality and safety of fresh produce at retail level in Korea in order to periodically update information and establish available risks associated with consumption of fresh fruits and vegetables. The samples from different markets located in 3 provinces of South Korea were collected. The protocol in the Korean Food Standards Codex was applied and generic Escherichia coli, coliforms, aerobic mesophilic bacteria (AMB), and yeast and mold (YM) in 360 packaged and unpackaged fresh fruits and vegetables were analyzed. Presence of pathogens was examined using real‐time polymerase chain reaction (q‐PCR) after enrichment of samples. For all, the microbial counts ranged from 1.7 to 10.6 log cfu/g for AMB, 2.2 to 7.9 log cfu/g for coliforms, and 5.5 to 7.9 log cfu/g for YM. Three lettuce samples were contaminated by E. coli with a bacterial load ranging from 2 to 4 log cfu/g. Salmonella spp. were not detected in any fresh produce. Listeria monocytogenes, E. coli O157:H7, and Staphylococcus aureus were found in 1 (0.6%), 3 (0.8%), and 5 (1.4%) fresh produce samples, respectively. Bacillus cereus (50.3%) and Clostridium perfringens (13.3%) had the highest prevalence. These results indicate the need for employing strict control measures and developing preventive strategies to improve the quality and safety of fresh produce in Korea.     

A Comparison of Organically and Conventionally Grown Foods—Results of a Review of the Relevant Literature

This review is concerned with the summary and evaluation of the results from more than 150 investigations comparing the quality of conventionally and organically produced food or of foods produced with the aid of different fertilisation systems. Cereals, potatoes, vegetables, fruits, wine, beer, bread, cakes and pastries, milk, meat, eggs and honey, as well as products made from them, have been included in the review. Most of the studies evaluated are physico-chemical investigations of concentrations of desirable and undesirable ingredients, pesticide residues, contaminants, sensory analyses and feed experiments with animals. Nutritional studies in humans and experiments which used holistic methods of analysis are also included. Since different methods of sampling were used in the investigations, a summary evaluation of individual results is extremely difficult. Even when the sampling methods are of the same type, a great many factors have to be taken into consideration which are not directly related to the production system but which do influence food quality to a large degree. Despite the heterogeneity of the sample material, some differences in quality between products from conventional and organic farming or foods produced with the aid of different fertilisation systems have been identified. © 1997 SCI     

Influence of Washing and Packaging on the Sensory and Microbiological Quality of Fresh Peeled White Asparagus

ABSTRACT: We evaluate the microbiological quality and physicochemical and sensorial characteristics of white asparagus washed with and without chlorine and packaged in 2 different types of film (perforated polyvinyl chloride [PVC] and P-Plus 160) when stored at 4 °C for up 15 d. Dehydration was the main cause of quality losses. Asparagus packaged in P-Plus maintained their fresh appearance better than those packaged in perforated PVC. The total sugar and ascorbic acid content decreased about 9% and 41% after 15 d, respectively. Peeled white asparagus packaged in perforated PVC or P-Plus kept a reasonable sensorial quality after storage at 4 °C for 15 d, although mesophile and psycrotroph counts of about 9 log CFU/g were reached in asparagus washed with water. The effect of washing and type of film on different microbial groups is discussed.     

传统养殖与组合湿地-池塘循环水养殖黄颡鱼的品质比较

为比较传统养殖与组合湿地-池塘循环水养殖黄颡鱼（Pelteobagrus fulvidraco）的品质差异,该研究对养殖池塘水质进行评价的同时,利用超高效液相色谱、气相色谱-质谱联用等技术分析了组合湿地-池塘循环水及传统池塘养殖黄颡鱼的表观及质地品质、营养品质、风味品质。结果表明,组合湿地-池塘循环水池塘水质污染程度较低、水体富营养化程度减缓且其中养殖的黄颡鱼肌肉空壳率、亮度及白度值显著高于传统组,肌肉的蒸煮损失率显著降低。湿地组黄颡鱼必需氨基酸/总氨基酸为40.40%,必需氨基酸/非必需氨基酸为78.67%,肌肉氨基酸组成更符合FAO/WTO推荐的理想蛋白模式。湿地组黄颡鱼不饱和脂肪酸、Omega-3脂肪酸及Omega-6脂肪酸含量分别为传统组的3.78倍、2.64倍以及3.25倍。湿地组黄颡鱼中呈油脂味等异味的挥发性气味物质含量下降,且呈苦味及酸味的氨基酸总占比下降,呈鲜味及甜味的氨基酸总占比上升,呈鲜味的IMP含量为传统组的3.16倍,呈苦味的Hx R及Hx含量较传统组下降了17.00%及17.57%。综上,组合湿地-池塘循环水养殖黄颡鱼可食用部分占比更高,肉质更为白亮,肌肉营养...     

Microbiological quality of fresh fruit and vegetable products in Catalonia (Spain) using normalised plate‐counting methods and real time polymerase chain reaction (QPCR)

BACKGROUND: Commercially available fruits and raw and ready‐to‐eat vegetables (n = 445) were examined for aerobic, coliform, and yeast and mould counts using normalised methods. Listeria spp., Listeria monocytogenes and Salmonella spp. were detected by real time polymerase chain reaction (QPCR) after enrichment. RESULTS: Aerobic plate counts ranged from < 10 to > 10⁹ colony‐forming units (CFU) g^?1, with the lowest and highest counts recorded for fruits and sprouts respectively. The highest incidence level of coliforms was found in ready‐to‐eat vegetables, with up to 65.7% of samples containing from 5 to 9 log₁₀CFU g^?1. Yeasts and moulds showed their highest incidence level between 5 and 6 log₁₀ CFU g^?1, with an overall range from < 2 to 9 log₁₀ CFU g^?1. Salmonella spp., Listeria spp. and L. monocytogenes were detected in 0.67, 2.7 and 0.9% respectively of the total samples examined. CONCLUSION: The samples analysed can be gathered into two main groups, one showing low microbial counts (fruits) and a second group (raw whole leaves and roots and packed ready‐to‐eat vegetables) with higher microbial contamination. Although incidence levels of pathogenic bacteria reported here are in the lower range of those reported elsewhere, positive detections highlight the importance of good hygienic measures throughout the whole food chain. Copyright © 2007 Society of Chemical Industry     

A Survey of Nitrate and Nitrite Concentrations in Conventional and Organic‐Labeled Raw Vegetables at Retail

A national survey of the nitrate () and nitrite ( ) concentrations in raw and highly consumed vegetables available at retail in the United States was conducted. A total of 194 samples of fresh broccoli, cabbage, celery, lettuce, and spinach categorized as conventional or organic by label were collected from 5 major cities in different geographic regions of the United States and analyzed to determine and concentrations. There were no differences in the mean values of conventional compared with organic vegetables taken from the 5 metropolitan areas. However, significant differences in mean pairwise comparisons between some conventional and organic vegetables for content were observed. The mean concentration of both conventional and organic vegetables ranged between 0.1 and 1.2 mg/kg of fresh weight (FW) with the exception of conventional spinach that contained 8.0 mg/kg FW. Mean contents of conventional broccoli, cabbage, celery, lettuce, and spinach were 394, 418, 1496, 851, and 2797 mg/kg FW, respectively, while their organic‐labeled counterparts averaged 204, 552, 912, 844, and 1318 mg/kg FW. In most cases, organic vegetables were numerically lower in content than their conventional counterparts. Based on survey results, the finding that low levels were observed in some organic vegetables in different cities may warrant further study to determine if true differences exist, due to production practices, seasonal differences, and the magnitudes of those differences. Furthermore, the geographic differences in content of vegetables may flaw estimates of daily and exposure.     

短波紫外线处理对鲜切果蔬品质及抗氧化活性的影响研究进展

鲜切果蔬因具有营养、便利、新鲜、可食率达100%等特点,越来越受到人们的关注。但鲜切果蔬由于受到机械损伤,其品质下降、易被微生物污染。短波紫外线作为一种非热力杀菌技术,近年来被研究者们用于鲜切果蔬保鲜,得到了良好的效果。本文介绍了鲜切果蔬及短波紫外线技术的特点,综述了短波紫外线处理对鲜切果蔬安全品质、营养品质及感官品质的影响及短波紫外线处理对鲜切果蔬抗氧化物质及抗氧化活性的作用,并讨论短波紫外线技术在鲜切果蔬中的应用前景,为短波紫外线处理鲜切果蔬的深入研究和推广应用提供重要的理论依据和参考。     

供应链中生鲜果蔬品质劣变机制、共性管控及智能检测技术研究进展

供应链中生鲜果蔬由于呼吸作用、蒸腾作用和乙烯释放等因素,持续消耗有机物质(如糖和淀粉),导致生鲜果蔬品质降低。在整个供应链中,生鲜果蔬的生理、生化变化受内在因素(种类与品种、产地与采收期、成熟度或生长期)和环境因素(如温度、湿度、O₂和CO₂体积分数、乙烯体积分数、挤压、撞击、振动等)的影响。目前,供应链中应用了许多采后技术来提高品质和保留率,以减少生鲜果蔬的品质劣变,提高其市场竞争力。作者简要介绍了供应链中生鲜果蔬品质劣变(如霉变、萎蔫、褐变、软化、黄化等)机制、生鲜果蔬品质劣变影响因素,以及通过采用共性管控技术减缓生鲜果蔬的品质劣变,并综述了智能标签在生鲜果蔬新鲜度检测中的研究进展。     

鲜食核桃和干核桃贮藏生理及营养品质变化比较

以‘辽河4号’核桃品种为试材,对鲜食核桃和干核桃在(0±1)℃冷藏条件下的贮藏生理及营养品质变化进行了研究。结果表明:鲜食核桃贮藏期间的呼吸强度、丙二醛(MDA)含量极显著(P<0.01)高于干核桃,过氧化物酶(POD)活性显著(P<0.05)高于干核桃,对其贮藏保鲜不利;但鲜食核桃的营养成分损失相对较少,尤其对氨基酸和γ-VE含量的保存有利,鲜食核桃中二者的含量极显著(P<0.01)高于干核桃;脂肪、蛋白质、VE总量及δ-VE含量与干核桃差异不显著(P>0.05)。     

马来酸酐改性茶多酚对非酶糖基化的抑制作用

食品加工过程中所涉及的高温处理常会引发非酶糖基化反应,导致一些有害成分的产生,因此加工过程中应尽量避免这一现象。本研究用马来酸酐作为改性剂,制备马来酸酐改性茶多酚（maleic anhydride modified tea polyphenols,MA-TP）,采用紫外-可见分光光度法、高效液相色谱法和荧光光谱法等研究改性茶多酚（tea polyphenols,TP）的抗氧化能力和对高温下非酶糖基化反应的抑制作用。结果表明：虽然MA-TP对2,2’-联氮-双-3-乙基苯并噻唑啉-6-磺酸阳离子自由基清除能力较TP显著降低（P＜0.05）,但能有效抑制非酶糖基化反应。MA-TP在赖氨酸-果糖非酶糖基化反应体系中对前体物质的形成和褐变程度的抑制作用较TP明显增强。MA-TP对二羰基化合物乙二醛、甲基乙二醛以及总体荧光性糖基化终产物的最高抑制率分别为82.95%、40.33%和70.25%,抑制效果显著优于TP和阳性对照氨基胍（P＜0.05）,其对3-脱氧葡萄糖醛酮的最高抑制率为45.01%,在反应中后期抑制效果显著优于TP（P＜0.05）;MA-TP对戊糖素的最高抑制率为88.43%,其抑制效果与TP无明显差异,但显著优于阳性对照氨基胍（P＜0.05）。综上,研究可为以改性TP作为非酶糖基化抑制剂在食品领域的应用提供理论参考。     

Level of Acrylamide Precursors Asparagine, Fructose, Glucose, and Sucrose in Potatoes Sold at Retail in Italy and in the United States

The free amino acid asparagine and the reducing sugars glucose and fructose has been reported to serve as precursors for the heat‐induced formation of potentially toxic acrylamide in a variety of plant‐based food. To contribute to our knowledge about the levels of these precursors, we used ion‐exchange chromatography to measure free asparagine and high‐performance liquid chromatography (HPLC) to measure free glucose, fructose, and sucrose in 9 potato varieties sold at retail in Italy and in 22 varieties sold in the United States. Asparagine levels (in mmol/kg of fresh wt) ranged from 1.17 for the Agata potatoes to 57.65 Russet potatoes, a 49.3‐fold variation from lowest to highest value. The corresponding levels for fructose ranged from 1.73 (Fingerling Ozette) to 33.63 (Red), a 19.4‐fold variation from the lowest to the highest value. For glucose, the concentration ranged from 1.11 (Jelli) to 34.73 (Yukon Gold B) potatoes, a 31.3‐fold variation from lowest to highest value. The corresponding values for sucrose ranged from 1.16 (Fingerling Ozette) to 40.61 (Marabel) potatoes, a 35fold variation. The American potato varieties Kennebec, White, and Fingerling Ozette and the Italian potato varieties Agria, Merit, and Marabel had very low levels of both asparagine and reducing sugars. The results may enable consumers, restaurants, and processors to select commercial potatoes with low levels of acrylamide precursors for baking or frying.     

中国蜂产品主要出口市场质量安全监管重点分析

在农产品国际贸易中,质量安全准入要求被认为是具有重要贸易影响的因素。入世后,受主要出口市场不断严格质量安全监管的影响,中国蜂产品国际市场占有率持续下降。在重点分析近年来日本、欧盟、美国蜂产品质量安全监管重点的基础上,本文就国际蜂产品质量安全监管趋势进行了讨论。     

鲜湿糙米线品质劣变机理及调控技术研究进展

全谷物以其对营养健康的重要作用在全世界得到了广泛关注。鲜湿糙米线作为营养健康的全谷物主食食品存在更易腐败、老化变硬、易断条、蒸煮损失率高等问题。系统阐述了鲜湿米线品质影响因素,鲜湿糙米线在储藏过程中的水分含量、pH值、蒸煮品质、水分迁移、质构、微观结构等品质变化规律,分析了鲜湿糙米线品质劣变机理;并进一步对选择糙米原料、外源添加物、糙米全籽粒磨粉及回填法制备工艺等鲜湿糙米线品质调控技术2016—2023年最新研究进展进行了综述,为鲜湿糙米线的品质调控和品质提升提供参考。     

不同贮藏温度下鲜湿米线的品质变化动力学模型及其货架期预测

为了研究贮藏过程中,鲜湿米线品质变化与贮藏时间的相关性,本文测定了4、10、20、25、37℃下贮藏的鲜湿米线的酸度、碘蓝值、pH值和吸水率随贮藏时间的变化,并建立了碘蓝值、pH值和吸水率的动力学模型,及以碘蓝值为终点的货架期预测模型。结果表明,鲜湿米线的碘蓝值和pH值可以建立一级动力学模型,吸水率可以建立零级动力学模型。且建立的三个模型的拟合系数R2分别为:0.9901(碘蓝值),0.9524(pH值)和0.9785(吸水率),并且其平均相对误差W分别为7.0%,5.8%和5.6%,均小于10%。以贮藏期间鲜湿米线碘蓝值的变化建立货架期模型,且货架期达终点时,碘蓝值为1.2389,其平均相对误差W为1.06%,小于10%。说明本文以碘蓝值作为终点时建立的货架期模型可以较好预测鲜湿米线的货架期。     

湿热地区不同贮藏温度对热鲜牛肉品质变化的影响

本文研究了湿热地区不同温度热鲜牛肉贮藏过程中食用品质、新鲜度、肌糖元含量和肌原纤维小片化指数的变化,旨为热鲜牛肉的食用提供参考。选取20月龄左右锦江黄牛6头,宰后立即取背最长肌作为原料,分别贮藏在温度为5℃、15℃、25℃和35℃和湿度为80%恒温培养箱。测定不同贮藏温度处理对热鲜牛肉贮藏过程中pH、感官指标(色泽、风味、弹性、组织状态和总体可接受性)、菌落总数、肌糖元含量和肌原纤维蛋白降解的变化规律。结果表明;随着贮藏时间长,不同贮藏温度热鲜牛肉pH呈先降低后升高,肌糖元含量和感官评分降低,菌落总数和MFI增加。综合分析;贮藏温度对热鲜牛肉的pH值、感官评分、菌落总数、肌糖元含量以及MFI变化具有一定影响。贮藏温度越高,失水率越高,微生物生长繁殖越快,肌原纤维蛋白降解程度越大。     

温度激化处理对采后果蔬贮藏品质影响的研究进展

综述了温度激化处理对采后果蔬贮藏品质影响及冷害的研究进展,主要涉及热激处理和冷激处理两种温度激化处理,并分别从果蔬品质与果实生理生化两大方面的影响具体论述,并对温度激化处理的发展方向进行了展望。适宜的温度激化处理有助果蔬硬度保持,较好地保证果实口感与风味并为人们所接受,抑制绿色果蔬叶绿素分解与黄化,果实失重率降低;降低果实呼吸速率,减少或抑制乙烯的释放并抑制相关酶的活性,控制并抑制多酚氧化酶与过氧化物酶等酶的活性升高,经高温或低温胁迫诱导产生诱导蛋白并合成新的蛋白保护细胞并具有抵御力,以及延缓细胞膜透性的增加和降低丙二醛的产生。     

南平特色烤烟非挥发性有机酸(盐)与感官质量的相关性分析

采用甲酯化、二氯甲烷萃取、气相色谱法定量检测了南平烟区烤烟中的12种非挥发性有机酸。结果表明,与感官评吸关系比较密切的有草酸、丙二酸、棕榈酸、油酸、亚麻酸、亚油酸、肉豆蔻酸和柠檬酸。简单相关分析表明,棕榈酸和亚麻酸对评吸指标表现为正相关外,其他成分都表现为负相关;典型相关分析表明,棕榈酸、肉豆蔻酸、丙二酸、亚麻酸、亚油酸、柠檬酸对感官指标的载荷较大,在典型变量中起主要作用;通径分析表明,草酸对香气质、杂气、刺激性、总得分的直接影响较大,亚麻酸对香气质、香气量、余味、刺激性的直接影响较大,亚油酸对刺激性的直接影响较大,油酸对香气量的直接影响较大,以上都表现为正向关系;丙二酸对杂气、刺激性和总得分的直接影响较大,表现为负向关系。     

蔗糖酯和单甘酯对速冻韭菜水饺馅品质控制作用的比较

目的：研究蔗糖酯和单甘酯两种乳化剂对速冻韭菜水饺馅料品质控制作用的比较。方法：以物质的量比为1∶1的无水乙醇和丙酮做为浸提液,提取测定速冻韭菜中叶绿素含量和类胡萝卜素含量;用顶空固相微萃取-气相色谱-质谱联用的方法测定韭菜挥发气体中有刺激性气味的气体（简称不良气体）占总气体的体积分数;对病理制片的方法稍加改进后观察乳化剂对速冻韭菜细胞结构的影响。结果：随着蔗糖酯质量分数的增加,叶绿素、类胡萝卜素的保留率均呈增大趋势,而不良气体占总气体的百分比呈减小趋势。冻藏3 个月后,1%蔗糖酯处理组韭菜中叶绿素保留量达到0.44 mg/g,类胡萝卜素达到0.052 mg/g,比对照组分别提高了83.3%和96.1%,冻藏3 个月后1%蔗糖酯处理组的不良气体占总气体的体积分数为42.08%,比对照组体积分数下降了13.2%。添加乳化剂后速冻的韭菜细胞从失水程度和结构完整性上均优于对照组。结论：在叶绿素、类胡萝卜素的保存以及对不良气体的控制方面,蔗糖酯的效果要优于单甘酯。在韭菜细胞结构的保存方面,添加乳化剂后速冻效果优于直接速冻。     

多级模糊综合评判模型在纺织品质量评比中的应用

根据多级模糊综合评判的数学模型,应用(m·,⊕)算子,对纺织品的质量评比进行了定量计算。