Effects of acid adaptation on the survival of Listeria monocytogenes on modified atmosphere packaged vegetables

The survival and growth of Listeria monocytogenes and L. innocua on ready-to-use (RTU) packaged vegetables (lettuce, swedes, dry coleslaw mix, bean-sprouts) were studied. The effects of acid adaptation of Listeria spp. on their survival during subsequent storage were also investigated. Listeria innocua behaviour was similar to that of L. monocytogenes on all vegetables examined. The survival and growth patterns of Listeria varied with the packaged product. Populations on packaged lettuce and swedes significantly increased ( P  < 0.05, by 1–1.5 log cycles) during a 14-day storage period. During the same period, Listeria counts gradually decreased (by 1–1.5 log cycles) on coleslaw mix. Acid adaptation enhanced survival of Listeria spp. during storage in packages of vegetables which had relatively high in-pack CO₂ levels (i.e. 25% in packaged coleslaw, bean-sprouts). It is concluded that adapting listerial cells to mildly acidic conditions rendered cultures more resistant to relatively high (25–30%) CO₂ atmospheres.     

Water management for food production: Strategy plan

This paper attempts to discover the real bottleneck of many irrigation projects: the complex of technical and nontechnical constraints which oppose the integrated and stable utilization of available soil and water resources. The efficiency of irrigation water use is the basic problem of intensive agriculture. Irrigation projects are, in the initial stage of operation, required to serve short-term objectives, such as to reach local self-sufficiency in food production. Their operation should, in the long run, nevertheless be based on a water-use concept and should reflect the desirable development of agriculture resulting from the need for further intensification and diversification of production. The establishment of the Water Management Strategy Plan for the Kirindi Oya Irrigation and Settlement Project in Sri Lanka is an example of the integrated approach to water resources development and management. This plan has been established on the basis of a multidisciplinary system analysis and simulation/optimization of the hydraulic and agricultural performance of the irrigation system.     

2019年冻鱼糜制品中食源性致病菌污染状况分析

目的 了解冻鱼糜制品中食源性致病菌污染状况。方法 从全国范围内采集冻鱼糜制品4 516份，按照食品安全国家标准《食品微生物学检验》相应标准的规定，对样品中单核细胞增生李斯特菌、副溶血性弧菌、小肠结肠炎耶尔森氏菌、致泻大肠埃希菌进行检验。结果 单核细胞增生李斯特菌检出率6.02%（272/4 516），副溶血性弧菌检出率0.84%（38/4 516），小肠结肠炎耶尔森氏菌检出率0.84%（38/4 516），致泻大肠埃希菌检出率0.91%（41/4 516）。单核细胞增生李斯特菌的污染在4种食源性致病菌中较为突出，且不同产地的样品中单核细胞增生李斯特菌的污染差异较大。除副溶血性弧菌以外，其余3种食源性致病菌在散装样品中的检出率均高于预包装样品。结论 市售冻鱼糜制品存在致病菌污染，需要关注其健康风险。     

Assessment of fermentation as a household technology for improving food safety: a joint FAO/WHO workshop

Food safety and nutritional aspects of lactic acid fermentation processes for the purpose of complementary food preparation at household scale in tropical countries were assessed during an FAO/WHO workshop held in Pretoria, South Africa in December 1995.

Lactic acid fermentation was evaluated in particular, taking into consideration that microbial fermentation is only a part of the food preparation processes involving other operations such as soaking, cooking and the use of germinated cereals. The latter are of special interest as they enable the preparation of semiliquid porridges of high-nutrient density.

The present state of knowledge concerning the antimicrobial effects imparted by the acidity in lactic-fermented foods was reviewed, as well as the nutritional benefits of fermentation and use of germinated cereals. Areas requiring further research were identified and prioritized.

It was concluded that high priority should be given to research on: the effect of lactic acid fermentation on viruses, parasites, some bacteria and mycotoxins; risk assessment using the HACCP approach, health education of food handlers and consumer perception of fermented foods; characterization and optimization of fermentation processes and development of appropriate starters; and some physiological and nutritional effects of consumption of fermented foods.     

Effects of superabsorbent polyacrylamides on efficiency of water use by crop seedlings

Cross-linked polyacrylamide expands upon contact with water to form a pliable gel that in a growing medium constitutes a reservoir of moisture available for uptake by plants. Trials with seedlings of three crop species (Lactuca sativa L, Raphanus sativus L, Triticum aestivum L) using measurements of yield and evapotranspiration ratio show that gel-stored moisture is utilised with a greater efficiency than conventional forms of water. Moreover, gel storage of water provides a buffer against temporary drought stress and the potential for reducing the risk of failure of certain crops at establishment.     

Food supply capacity study at global scale

The world population is expected to grow to 10 billion people in 2040, requiring food production at least to triple, as a combined result of population growth and dietary changes. In this study scenarios for food security are developed for 15 major regions of the world. Food production is calculated on a 1°x1° grid basis, using inputs from a digital data base containing soil, climatic, agronomic and demographic data. This allows us to study impacts of different production scenarios and their environmental side effects. Soil area data are derived from the digitized FAO soil map, considered to be representative for soil units on a 1°x1° grid; weather variables of 978 stations are allocated to the grid cells. Food production estimations are made with a simple crop growth module, a soil water balance and a soil nitrogen balance. Calculations are done on a grid basis, each grid cell being characterized by its suitability for arable farming or grassland, soil and climatic conditions and the availability of irrigation water. Results of Yield Oriented Agriculture (YOA) and Environment Oriented Agriculture (EOA) production scenarios on food self-sufficiency are presented. If we assume that there is no limit to transport of food across the globe, YOA allows the entire globe an affluent diet, while EOA allows only a moderate diet. For this scenario, regional self sufficiency indices vary widely: most regions can produce food required for an affluent diet, but not East, South and West Asia that account for 48% of the expected global population in 2040. Also Southeast Asia (9% of expected global population in 2040) and West and North Africa (10%) come close to the lower limit for food self-sufficiency. With EOA, only the former USSR, North and South America, Central and Southern Africa and Oceania can offer their future populations an affluent diet. Southern Asia will experience food shortages even under minimum food demand, and less affluent diets do not provide a solution. In this paper, attention is given to the methodology regarding soils, and to the uncertainty regarding soil and water in input data. Particularly soil suitability for agriculture for each of the grid cells has a large effect on model calculations, as it is a rather rough approximation. Knowledge of soils across the world shows important weaknesses with respect to the extent of coverage, extrapolation of point observations to grid cells, definition of soil characteristics compatible with crop models, and handling of preferential flow in soil profiles. We emphasize the need for digitized, reliable and readily available natural resource information in the fields of soil surveys, climatology, irrigation water availability, land use and land cover. The ultimate goal of the approach is not to predict the future of global agriculture, but to allow decision makers to compare various scenarios for food self-sufficiency, and to raise awareness regarding issues related to food security. In spite of the above-mentioned shortcomings in basic data, it is demonstrated that it is possible to develop the required scenarios now, instead of having to wait on more reliable soil information.     

磷肥厂氟化物对周边农作物的危害与防治

对云南三环化工有限公司厂界周边农作物中氟化物含量进行常年的跟踪监测,分析氟化物排放对厂界周边农作物的危害。结果表明,氟化物污染危害程度与烟囱排放高度、气象条件、排放浓度及农作物本身抗性等因素有关,提出了氟化物污染的防治对策和建议。     

几种药剂对玉米红蜘蛛的室内和大田药效

几种杀螨剂对玉米红蜘蛛窜内药效结果显示:对玉米红蜘蛛的主要种类--截形叶螨第7天的室内防效为28%哒螨灵乳油(78.3%)>240 g/L螨危FS(76.7%)>1.8%阿维菌素乳油(72.O%)>40%炔满特乳油(65.9%)>40%氧乐果乳油(63.3%)>2.5%溴氰菊酯乳油(58.3%).大田试验结果表明:30 d后以240 g/L螨危FS 150 mL/hm2的效果最佳,防效为76.8%;氧乐果由于在当地长期使用,效果已经很不理想,防治效果只有38.7%.     

农作物秸秆用于制备活性炭的研究进展

中国农作物秸秆产量很大,秸秆资源的利用领域在不断扩大。活性炭具有发达的孔隙结构、大的比表面积和较好的吸附能力。文章介绍了稻壳、稻秸秆、玉米秸秆、麦秸秆、烟秸秆、蚕豆秸秆(壳)、棉秸秆、青稞秸秆、桑树秸秆、油菜秸秆、麻类秸秆等制备活性炭的工艺方法以及活性炭的性能。