An enzyme immunoassay for nisin

The development of an enzyme-linked immunosorbent assay (ELISA) for nisin using polyclonal antiserum is described. The method has a limit of detection of 1.9 X 10⁻² i.u. ml⁻¹ and correlates well with the bioassay. Its use in the analysis of commercial processed cheese samples is described and the results obtained compared with those from the bioassay.     

智慧溯源系统构筑食品安全懿“防护墙”

食品安全问题日益成为全社会关注的话题,人们也在不断地探寻解决食品安全问题的各种途径和方法。本文结合物联网的智能标签、智能感知、智能控制与反馈的特征,在食品安全领域提出了食品智慧溯源的思想,将物联网应用于食品溯源中,使溯源系统有了“神经末梢”、“神经中枢和大脑”以及和用户的“对话”能力,提高了食品溯源能力,为食品安全构筑了一道坚固的“防护墙”。     

Consumption patterns,bacteriological quality and risk factors for Salmonella contamination in meat-based meals consumed outside the home in Kigali,Rwanda

Meat-based meals are consumed as a source of animal proteins and constitute one of the leading vehicles for food borne infections in humans. The main objective of this study was to determine the consumption pattern and the bacteriological quality of meat-based meals consumed outside households in Kigali. A survey on meat consumption patterns was carried out in 400 households by using a questionnaire, whereas different meat-based meals were sampled from 150 snack bars and restaurants. Enumeration of hygiene indicator bacteria (total mesophilic bacteria and Escherichia coli) and the qualitative detection of Salmonella were carried out by using conventional culture methods. The results indicated that goat was the type of meat that was consumed the most outside the home in Kigali and the meat intake varied significantly (p ≤ 0.05) with the social category of the household. The average levels of total aerobic bacteria and E. coli in meat-based meals were found to be 4.7 and 1.4 log cfu/g, respectively, whereas Salmonella was detected in 11.7% of all meat-based meals. Eight factors mostly linked to the cooking treatments and hygienic handling practices for cooked meals were found to be significantly (p ≤ 0.05) associated with the risk of Salmonella occurrence in meat-based meals consumed outside the home in Kigali. The findings from this study strongly suggest the need for proper cooking and/or improvements in hygiene in the establishments selling ready-to-eat meat-based meals in Kigali, particularly those located in rural localities.     

Tenacity of Bacillus cereus and Staphylococcus aureus in dried spices and herbs

Numerous studies examined the antimicrobial effects of spice and herb extracts, whereas little is known about the effects of dry condiments on the survival of microorganisms. This study investigated the impact of dried condiments on the survival of Bacillus cereus and B. thuringiensis spores as well as Staphylococcus aureus cells. In addition, the survival variability between different strains was evaluated. Condiments (allspice, basil, cinnamon, nutmeg, oregano, paprika, parsley and pepper) were artificially contaminated by a dry spiking method using sand as carrier matrix and as control. The results show that counts of B. cereus and B. thuringiensis spores (initial spore count 5.6 ± 0.2 log₁₀ cfu/g and 6.7 ± 0.1 log₁₀ cfu/g, respectively) did not decline significantly in all condiments over a period of 50 weeks. In contrast, in some of the spiked test materials, cell counts of S. aureus (initial cell count 8.1 ± 0.5 log₁₀ cfu/g) were reduced below the detection limit of 10 cfu/g within 10 weeks of storage. D values for S. aureus ranged between 5 and 31 days depending on the strain, condiment and initial contamination level. In conclusion, dried condiments may not affect the survival of spores but can significantly affect the survival of non-spore forming bacteria. As strain variability can occur, tenacity studies should be conducted including a variety of strains.     

甲基对硫磷溶液的荧光光谱及其特性————

为了研究甲基对硫磷溶液的荧光光谱及其特性,采用多功能光谱测量系统,对甲基对硫磷标准溶液在紫外光激励下的荧光光谱特性进行了实验研究。利用GAUSSIAN软件与量子力学理论进行了理论分析,获得了其荧光光谱的产生机理以及甲基对硫磷分子的相应跃迁能级差,估算了其中直线型结构的荧光团的电子跃迁能级差,估算值与理论值误差不大。结果表明,在波长为200nm～320nm的紫外光激励下,甲基对硫磷标准溶液产生4个荧光峰,分别位于435nm,467nm,567nm,650nm,最佳激励波长为200nm和295nm。4处荧光峰分别是溶剂丙酮分子中C=O上的n电子跃迁、硝基上的n电子跃迁、甲基对硫磷分子中氧原子与苯环形成的大共轭电子结构跃迁以及P=S上的n电子跃迁共同作用产生。以上结果对食品安全监管等领域检测有机磷农药含量是有帮助的。     

Effects of feeding an aquatic weed Lemna trisulaca as partial replacement of fish meal on the performance of growing ducklings

Growing ducklings were fed diets containing an aquatic weed Lemna trisulaca meal (LTM) replacing, on a protein basis, either 40, 60 or 80 g kg^?1 of the fish meal (FM) from a control diet which contained 120 g FM kg^?1. Partial replacement of FM (40 and 60 g kg^?1 of the FM) by LTM on a protein basis showed good growth and low food consumption but food conversion efficiency was found to be comparable. It was concluded that LTM could be considered as a protein feed supplement for growing ducklings and also as a part replacement of animal protein (FM) in the nutrition of growing ducklings without deleterious effect on performance.     

Heat and Moisture Transfer in Composite Food—Theoretical Analysis of Influence of Surface Conductance and Component Arrangement

Heat and moisture transfer in composite bodies undergoing drying was simulated using a previously developed mathematical model which included the chemical potential of moisture as a mass transfer potential. Composite bodies included layered cylinders and concentric spheres consisting of a starch granule hydrate (H) and a hydrate of starch granules-sucrose 3:l mixture (S). The influence of the following factors on heat and moisture transfer was examined: convective surface mass transfer conductance, initial moisture, and component arrangement. The three factors significantly influenced moisture transfer white they had slight influence on heat transfer. Overall drying rate of each composite body was infhrenced interactively by moisture fluxes, which were caused by a surrounding drying medium and by a mass transfer potential difference across the interface of H and S.     

冻结肉类食品远红外辐射加热解冻的可行性研究

低温冻藏食品在利用之前必须经过解冻。解冻方法和装置的研究是食品冻藏技术的难题，各国都在不断地研究开发。本文介绍了肉类食品解冻的要求，进行了红外辐射加热解冻的模拟实验后，初步得出单独应用远红外辐射加热技术解冻实用价值不大的结论，指出一般红外烤箱不宜用作冻结食品的解冻。     

基于Kinect体感技术开发幼儿认知系统技术可行性研究

基于Kinect体感器开发一套幼儿认知系统,以激发幼儿认知的兴趣,陶冶幼儿的情操,促进幼儿的智力发展,提高幼儿的认知能力。幼儿认知系统是基于Kinect的体感技术,借助Kinect感应系统来定位捕捉幼儿动作及识别幼儿的语音信息,通过Kinect体感设备与计算机系统连接,将动作及语音信息输入系统,实现幼儿与系统之间互动,带幼儿进入模拟真实的认识环境中,沉浸在虚拟现实中进行认知训练,在娱乐中提高幼儿认知能力。