Foodborne transmission of Listeria monocytogenes via ready-to-eat salad: A nationwide outbreak in Switzerland, 2013–2014

From 26 October 2013 to 23 April 2014, 32 cases of listeriosis infected with an Listeria monocytogenes strain serovar 4b, sequence type 4 and belonging to a single distinct PFGE pulsotype were registered in patients from several cantons of Switzerland. L. monocytogenes was detected in blood (75%), CSF (16%), ascites (6%) and in joint fluid (3%) samples. By the end of March 2014, a food producing company reported an L. monocytogenes contamination of ready-to-eat salads to the authorities after detecting the pathogen through its in-house routine quality control. Product and environmental samples collected during subsequent investigations yielded isolates, matching the outbreak strain, thus confirming that ready-to-eat salad from this company was most likely the outbreak source. The cause for the product contamination was related to a design-inherent hygienic problem of one specific product-feeding belt. Complementary patient interviews also identified ready-to-eat green salads bought at one retailer as the likely outbreak source.     

Commiphora myrrha (Nees) Engl. extracts: evaluation of antioxidant and antiproliferative activity and their ability to reduce microbial growth on fresh‐cut salad

With the aim to develop natural preservatives displaying also chemopreventive activity, different Commiphora myrrha (Nees) Engl. extracts were studied. Myrrh essential oils, obtained by steam distillation and microwave‐assisted hydrodistillation, and several other extracts, obtained by sequential procedures with petroleum ether (PE), ethanol, ethyl acetate and butanol, have been screened for their antioxidant (DPPH· scavenging assay) and antiproliferative activity (on both nontumour and colon cancer cell lines) without previous purification. Considering that the colon cancer cell lines were more sensitive to PE and ethanol extracts, the latter of which showed the highest antioxidant activity (EC50 = 0.160 ± 0.008 mg mL^?1), both have been selected for further antibacterial/antifungal activity tests using an antimicrobial diffusion test and a growth inhibition test on salads. Results showed that the ethanol extract possessed the higher antibacterial and antifungal activity. Compared to untreated product, fresh‐cut salads treated with these two myrrh extracts displayed a significant lower bacterial growth. Although further investigation is required, these promising results offer hints as how to improve the shelf life of fresh‐cut salad.     

即食凉拌海带丝工艺的研究

研究了以干海带为原料制成即食凉拌海带丝工艺。结果表明,将海带丝于2．0％醋酸＋1％黄酒混合液中浸泡15min,可以有效去除海带的腥味;脱腥后的海带丝放于有效氯为50mg／kg的二氧化氯中浸泡3min,可以起到很好的减菌效果;冷藏温度与保质期的关系密切,以细菌总数为评价指标,5℃冷藏,产品的保质期可达49d．     

色拉油磷含量对其品质的影响

讨论了色拉油磷含量对其品质的影响,并提出了降低色拉油磷含量的方法及理论依据,确保产品既要符合国家标准,又要满足不同用户基本质量要求.     

米糠色拉油中试研究报告

选用国产定型设备与自行设计的脱蜡和脱脂专用设备组成米糠色拉油精炼生产线。在多次生产试验的基础上,确定了先脱胶、脱蜡,后脱酸、脱色、脱臭及冬化脱脂的工艺路线。用国产设备及生产线炼制出达到国家质量标准的米糠色拉油     

色拉油瓶盖注射模设计

分析了瓶盖塑件的结构特点 ,即有4处需强制脱模 ,故在设计模具时采用了与传统结构不同的五板四开式结构 ,并介绍了模具的工作过程。     

花生蛋白水解物对色拉酱贮藏稳定性的影响

该文将花生蛋白水解物以不同的添加量(0.25%、0.5%、1%,质量分数)添加到色拉酱中,探索花生蛋白水解物对色拉酱贮藏稳定性的影响,测定了离心乳析率、离心破乳时间、黏度、过氧化物生成量(peroxide value,POV)、硫代巴比妥酸(thiobarbituric acid,TBA)值以及蛋白水解物的分布等指标。结果表明,花生蛋白水解物的添加量越多,发生乳析现象越低,且能增加破乳时间和黏度,使色拉酱的乳化效果增强。并且,花生蛋白水解物能够吸附在油水界面上,显著降低色拉酱4周贮藏期间的POV和TBA值,有效地抑制了油脂的氧化。     

Combined effect of an O2 absorber and oregano essential oil on shelf-life extension of Greek cod roe paste (tarama salad) stored at 4 °C

In the present study the combined effect of an O₂ absorber and oregano essential oil (0.1% v/w) on shelf life extension of Greek cod roe paste (tarama salad) stored under refrigeration (4 °C) was investigated. The study was based on microbiological [Total viable count (TVC), Lactic Acid Bacteria (LAB), Enterobacteriaceae, H₂S-producing, yeast and molds and Clostridium spp.), physicochemical (pH, fatty acid composition, thiobarbituric acid (TBA), and color) and sensory (color, odor, and taste) changes occurring in the product as a function of treatment and storage time. Aerobically packaged tarama salad stored at 4 °C was taken as the control sample. Results showed that TVC exceeded 7 log cfu/g on day 12–13 of storage for control samples and day 31–32 for samples containing oregano oil. Samples containing either the O₂ absorber or the O₂ absorber plus oregano oil never reached 7 log cfu/g during the 60 day storage period. LAB were only partially inhibited by the oregano oil and/or the O₂ absorber. Yeasts and molds were totally inhibited by the O₂ absorber. Enterobacteriaceae populations were below the method detection limit (2 log cfu/g) H₂S-producing bacteria were the dominant spoilage microorganisms. Clostridum spp. was absent in 25 g sample. pH decreased from an initial value of 4.36 to 3.03 depending on specific treatment. Color parameters L and b increased and a decreased in control samples as well as in samples containing oregano oil. Color parameters remained unaffected in samples containing the O₂ absorber. TBA expressed as malondialdehyde (MDA) values increased from 1.5 mg/kg to 3.4, 3.2 and 2.9 mg/kg for samples containing oregano oil, the O₂ absorber and O₂ absorber plus oregano oil at the point of sensory rejection, respectively. Saturated fatty acids (SFA) increased during storage with a respective decrease in monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) both in control samples and samples containing oregano oil. Fatty acid composition remained unaffected in all samples containing the O₂ absorber. Sensory shelf life was 24 days for the control samples, 32 days for samples containing oregano oil, 60 days for samples containing the O₂ absorber and at least 60 days for samples containing the O₂ absorber plus oregano oil.

Industrial relevance

Oxygen absorbers as well as plant essential oils are considered natural means of preservation and may substantially extend the shelf life of foodstuffs while maintaining desirable sensory attributes (taste, odor and color).