微酸性电解水去除蔬菜农药残留效果的研究

目的探讨微酸性电解水(slightly acidic electrolyzed water,SAEW)对蔬菜农药残留的去除效果。方法 利用酶抑制法,建立了蔬菜表面农药残留的定量分析方法 ,酶活抑制率与农药浓度近似呈对数关系,对辛硫磷的检出限为0.49 mg/kg。结果与普通自来水浸泡处理效果比较,SAEW浸泡的去除效果有显着提高(P0.05),处理30 min后,农药去除率高达92%。随着SAEW用量的增加、浸泡时间的增长、以及温度的升高,农药残留率不断降低、农残去除率不断地增加。结论 SAEW由于其特殊的理化性质能有效地降解蔬菜的农药残留,它可能对蔬菜上面有机磷农药起到有效的降解作用,更多问题还有待研究。     

Effects of a family-based sensory education on vegetable and fruit variety in children

Several experimental studies implemented in schools have shown that sensory education reduces children’s neophobia and increases their sensory discrimination abilities. However, it is not known whether sensory education has an effect on children’s consumption, particularly on the variety of fruits and vegetables consumed, and whether it is effective when implemented in families.The effect on fruit and vegetable intake of a five months family-based sensory programme was examined in children aged 7–11 (with 32 children in the intervention group and 19 in the control group). The children's parents completed four 24-hour recalls at the beginning and after the intervention to assess their children’s fruit and vegetable intake. Variety indexes were calculated on the basis of the number of different fruits or vegetables consumed during the four 24-hour recalls.The results showed that the vegetable variety decreased in the control group, while it remained stable in the intervention group. No effects of the programme were observed for the fruit variety.The sensory education programme implemented in families prevented the variety of vegetables from decreasing over time. The results of this preliminary study and its long-term effects need to be confirmed by further investigations, with a different methodology than the 24-hour recall.     

Evaluation of Zataria multiflora Boiss. essential oil activity against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes by propidium monoazide quantitative PCR in vegetables

Essential oils (EOs) have long been applied as flavoring agents in foods, and due to their content in antimicrobial compounds, they have potential as natural agents for food preservation. Recently, real-time PCR in combination with PMA has successfully been applied to discriminate between live Escherichia coli O157:H7 and dead bacteria killed by cumin, clove, oregano and cinnamon EOs. In this study, initial experiments were performed in order to elucidate the minimum bactericidal concentration of Zataria multiflora EOs on E. coli O157:H7, Salmonella enterica and Listeria monocytogenes. Thereafter PMA-qPCR was applied in order to selectively quantify life cells within a bacterial population treated with Z. multiflora EO. Inactivation was obtained at EO concentrations of 0.02, 0.035, 0.045 for L. monocytogenes, E. coli O157:H7 and S. enterica, respectively. L. monocytogenes were totally killed in 30 min while it took 1 h 30 min for the gram negative pathogens. As a conclusion Z. multiflora EO has potential as natural food additive or biopreservative since it was able to irreversibly inactivate the three pathogens tested, at lower concentrations than other EOs and short exposition times. In addition, the PMA-qPCR approach proved efficient to selectively detect live pathogenic bacteria in vegetables following inactivation with Z. multiflora EO.     

Consumption of raw vegetables and fruits: a risk factor for Campylobacter infections

The purpose of this study was to determine the prevalence of Campylobacter in fresh vegetables and fruits at retail level in the Netherlands, and to estimate its implications on the importance of vegetables and fruits as risk factor for campylobacteriosis.Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a prevalence of 0.23% (95% confidence interval (Cl): 0.12-0.39%). The prevalence of packaged products (0.36%, 95% Cl: 0.17-0.66) was significantly higher than of unpackaged products (0.07; 95% Cl: 0.01-0.27). No statistical differences were found between seasons.Combining the mean prevalence found in this study with data on the consumption of vegetables and fruits, an exposure of 0.0048 campylobacters ingested per person per day in the Netherlands by transmission via vegetables and fruits, was calculated. This exposure, as input in a Beta-Poisson dose-response model, resulted in an estimated number of 5.3 × 10⁵ cases of infection with Campylobacter per year for the whole Dutch population. This constitutes the consumption of raw vegetables and fruits, especially when packaged, to be a risk factor for Campylobacter infections.     

栅栏技术在鲜切菜生产中的应用

介绍了栅栏技术的基本原理,分析了鲜切莱易出现的质量问题及控制鲜切菜质量的栅栏因子,概述了栅栏技术在鲜切菜生产中的应用。     

螺旋杀青机的热力学分析及结构参数的确定

通过对螺旋杀青机的热力学过程的分析，得出杀青机满足果蔬杀青效果所应具有的机械参数，即杀青机长度L，杀青机的外箱体的下圆弧半径R2，滚筒的外径R1，内径r等，为设计杀青机CAD的专用软件奠定了理论基础。     

Carotenoids and chlorophylls in processed xanthophyll-rich food

Processing of food modifies nutrient contents and food matrices. The present analyses provide information about the effects of heat steam sterilization (HSS), high pressure processing (HPP) and common household cooking on the stability of carotenoids and chlorophylls in spinach, parsley, dill and kale. For HSS, samples were heated in an autoclave for 5, 10, 15 and 20 min at 121 °C. Additionally, one sample was treated via HPP at 200, 400 and 600 MPa for 5, 10 and 40 min at room temperature. Carotenoid and chlorophyll contents were determined by reversed-phase HPLC. Lutein was the most abundant carotenoid in all samples. Furthermore, violaxanthin, zeaxanthin, β-carotene, chlorophylls a and b were quantified. Thermal treatment via HSS led to a significant decline of contents of lutein, chlorophylls a and b. HPP did not reduce the amounts of xanthophylls and chlorophylls. Conclusively, HPP seems to be a good alternative to HSS for the preservation of xanthophyll-rich food.     

Innovative processes and technologies for modified atmosphere packaging of fresh and fresh-cut fruits and vegetables

Modified atmosphere packaging (MAP) technology has been commercially viable since the 1970s. Currently, MAP is extensively used worldwide to preserve the quality and extend the shelf-life of whole fresh fruits and vegetables, but is also increasingly used to extend the shelf-life of minimally processed fresh fruit and vegetables. This review discusses new processes and technologies that can be used to improve quality preservation and consumer acceptability of minimally processed produce where high respiration rates and challenging degradation processes operate. New packaging innovations are enabling producers and retailers to further maintain quality for longer. Innovative approaches to extend shelf-life include active MAP with differentially permeable films, films that incorporate antimicrobial properties, edible coatings that confer barriers properties, and the use of non-traditional gases to modify respiration. Intelligent packaging using integrated sensor technologies that can indicate maturity, ripeness, respiration rate and spoilage are also appearing. This review demonstrates that preservation technologies and associated packaging developments that can be combined with modified atmosphere are constantly evolving technology platforms. Adoption of combinations of technology improvements will be critical in responding to commercial trends towards more minimally processed fresh-cut and ready-to-eat fruit and vegetable products, which require specialized packaging solutions.     

A rapid multi-residue method for the determination of pesticide residues in choi sum, yardlong beans and aubergines

A rapid multi-residue modified QuEChERS method has been developed to analyse 20 pesticide residues in choi sum, yardlong beans and aubergines by gas chromatography with flame photometric and electron capture detectors. Primary secondary amine in dispersive form was omitted in the extraction step but instead packed in a Pasteur glass pipette for column cleanup. The recoveries for all 20 pesticides except chlorothalonil at 10-500 μg kg⁻¹ fortification levels ranged from 74.0% to 117%. Similar recoveries of 81.7-117% were obtained for all organochlorine and pyrethroid pesticides including chlorothalonil using silica gel cleanup. The relative standard deviation obtained was below 14.9%. The limit of quantification was in the range 1-10 μg kg⁻¹. The method has high selectivity for pesticides in vegetables containing high amount of chlorophyll, pigment and coloured compounds such as in choi sum and aubergines. The method was used to analyse 132 vegetable samples from residue survey.     

混合辐照饲料喂养大鼠的骨髓多色性红细胞微核细胞率观察

本文用两组辐照饲料对Wistar大鼠进行了110天和150天喂养,观察其骨髓多色性红细胞(PCE)的微核效应。一组为混合辐照饲料组,辐照饲料占80％;另一组为辐照蔬菜组,辐照蔬菜占总饲料的3％,辐照剂量为2KGy,是实际需要的辐照剂量2倍以上。同时设有普通饲料的阴性对照组,和用环磷酰胺处理或给以全身整体照射的阳性对照组。微核测定采用Giemsa染色法、Harris苏本精复染法和荧光染色法,两批实验均表明,在本实验条件下,不论是喂养混合辐照饲料还是辐照蔬菜,都未见到大鼠骨髓PCE微核细胞率有所增高。