Continuous in-line decontamination of food-processing surfaces using cold atmospheric pressure air plasma

This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and against S Typhimurium on commercial poly[ether]-thermoplastic poly[urethane] (PE-TPU) conveyor belts, under simulated conditions of a food-processing facility. A significant level of microbial inactivation was achieved, up to 3.03 ± 0.18 and 2.77 ± 0.71 logCFU/mL reductions of L. monocytogenes and S. Typhimurium respectively within 10 s total treatment on stainless steel surfaces, and a 2.56 ± 0.37 logCFU/mL reduction of S. Typhimurium within 4 s total treatment on the PE-TPU material, according to a procedure based on the well-established EN 13697:2015 industrial protocol. CAP exposure was shown to have a minor impact on the morphology and composition of the treated surfaces. The results indicated that CAP can be applied for effective and continuous disinfection against common foodborne pathogens in food-processing facilities.Industrial relevanceLow temperature plasmas have shown great promise for microbial decontamination, yet industrial uptake of the technology has been limited due to scaling limitations. In this study, a prototype conveyor-based CAP decontamination system was developed and tested under realistic conditions expected within a food-processing facility. The results showed a high level of antimicrobial action against two common foodborne pathogens within a few seconds of CAP exposure, a timescale in line with industrial line processing speeds. Our findings demonstrated that CAP shows great promise for the continuous in-situ decontamination of food contact surfaces, with the potential to mitigate against the costly downtimes incurred in current production line practices implementing chemical disinfectants.     

The effect of glaze uptake on storage quality of frozen shrimp

Ice-glazing is applied to protect the frozen shrimp from undesirable quality changes during frozen storage. Effects of initial frozen shrimp temperature on glaze uptake; glazing time on glaze uptake; and different glaze percentage on physical and chemical changes of frozen shrimp during storage were investigated. Shrimps were frozen in a spiral freezing machine (?35 °C/15 min); transferred to the air blast freezer until the core temperature reached ?18 °C, ?25 °C and ?30 °C; submitted to glazing process; and stored at ?18 °C for 180 days. The glazing percentage, pH and N-TVB levels were monitored every 45 days. This study has demonstrated the effectiveness of the glazing process as a protecting agent for frozen shrimp. A reasonable range of water uptake could be between 15% and 20% to guarantee the final quality. Therefore, it is important to prevent temperature fluctuations during transportation and storage to maintain the quality of the frozen shrimps.     

鲟鱼头汤对产后缺乳大鼠泌乳功能的促进作用

目的：研究经蒸煮后高压液化熬制鲟鱼头汤的催乳功效。方法：将Wistar母鼠随机分为空白组（生理盐水）、缺乳模型组（溴隐亭）、阳性对照组（乳清蛋白鲈鱼粉）和实验组（鲟鱼头汤）,每组6只,对哺乳期Wistar母鼠进行连续14 d灌胃,考察其体质量和泌乳量变化。通过苏木精伊红染色、免疫组化分析、酶联免疫吸附测定与实时荧光定量聚合酶链式反应等方法测定母鼠乳腺组织形态、相关激素与蛋白表达水平。结果：实验组母鼠乳腺的腺管与腺泡中可以观察到棕黄色阳性显色蛋白分泌物数量增多,乳腺小叶间脂肪结缔组织数量减少,相较于模型组有明显恢复。与模型组相比,实验组母鼠每小时泌乳量、乳腺相对质量以及仔鼠窝重净增率均显著提高（P<0.05）,母鼠血清与乳腺组织中催乳素（prolactin,PRL）、催乳素受体（prolactin receptor,PRLR）、β-酪蛋白（β-casein,β-CN）、α-乳清蛋白（α-lactalbumin,α-LA）水平及乳糖合成酶（lactose synthase,LS）和脂肪酸合成酶（fatty acid synthase,FAS）活力也显著提升（P<0.05）。乳腺...     

Tracer experiments in fixed beds: effects of flow maldistribution on the estimation of transport kinetic parameters

A systematic study of liquid phase axial dispersion was conducted in glass columns (inner diameters, 1 cm and 1.6 cm), packed randomly with granular sand, by varying the fluid flow rate, particle size and bed height. Pulse and step response techniques, with KCl as an inert tracer, were used. The resultant data, covering the Reynolds number range from 1 to 50, are presented as plots of the Peclet number based on particle diameter against Reynolds number.Inert tracer experiments were also carried out in a column (inner diameter, 1.6 cm) packed with activated carbon granules, using different particle sizes, fluid flow rates and bed heights, in order to estimate the effective intraparticle diffusivity. We show that flow maldistribution produces pulse response curves with sharp, narrow peaks which, when compared with theoretical curves, result in small intraparticle diffusivities.We illustrate how the outer-phase transfer function can be obtained from the overall transfer function of the activated carbon bed and we compare it with the transfer function obtained directly using impermeable particles similar to the activated carbon granules.     

葡萄糖对快速发酵虾头酱中组胺抑制的作用

为探讨葡萄糖对快速发酵虾头酱中组胺的抑制作用,提高其安全性,本论文以新鲜虾头为原料,采用外接微生物快速发酵工艺,分别向虾头酱中添加2%、4%和6%葡萄糖,检测了虾头酱发酵过程中组胺含量的变化。对虾头酱发酵期间的TVB-N含量、氨基酸态氮及pH的变化进行了探讨,通过比较理化指标、菌落总数以及感官评价分析虾头酱的品质。结果表明,葡萄糖的添加能显著降低组胺的生成,添加2%、4%和6%的葡萄糖分别能降低54.6%、57.2%和43.2%的组胺;葡萄糖的添加一定程度上促进了TVB-N的生成,增加了产品总糖含量以及降低了氨基酸态氮的含量和pH,但并不影响蛋白质、脂肪、水分及菌落总数的含量;感官评价表明,产品风味相似度较高,葡萄糖的添加能明显抑制产品的氨气味。因此,虾头酱中添加2%、4%和6%的葡萄糖能降低组胺含量以及减少氨气味,同时产品也保持较高的品质特性。     

Sanitization potency of slightly acidic electrolyzed water against pure cultures of Escherichia coli and Staphylococcus aureus,in comparison with that of other food sanitizers

The sanitization potency of slightly acidic electrolyzed water (SAEW) on pure cultures of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was evaluated. The potency was compared with that of strong acidic electrolyzed water (StAEW) and sodium hypochlorite (NaOCl) solution. SAEW (ca. pH 5.8 and 21 mg/l available chlorine concentration; ACC) resulted into >5 log₁₀CFU/ml reduction of E. coli and S. aureus after 90 s of exposure. The relative bacterial reduction potency at each exposure time was in the order StAEW > NaOCl > SAEW and increased with exposure time, with relative effect being 90 s > 60 s > 30 s. The results indicate that SAEW with low ACC and near neutral pH can potentially sanitize E. coli and S. aureus within a short period of exposure presenting a potential replacement to NaOCl solution commonly used in the food industry.     

Biogenic amines content,histamine-forming bacteria and adulteration of bonito in tuna candy products

Thirty-four tuna candy products sold in retail markets and supermarkets in Taiwan were purchased and tested to determine the biogenic amine, histamine-forming bacteria, and adulteration of bonito meat. The levels of pH value, water activity (Aw), water content, total volatile basic nitrogen (TVBN), aerobic plate count (APC) and total coliform (TC) in all samples ranged from 5.3 to 6.1, 0.47 to 0.65, 7.37% to 17.32%, 12.1 to 54.6 mg/100 g, <1 to 6.2 log CFU/g and <3 to 1700 MPN/g, respectively. None of these sample contained Escherichia coli. The average content of various biogenic amines in all tested samples was less than 1.0 mg/100 g. Four histamine-producing bacterial strains isolated from tested samples produced 1.02–1.74 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH) after incubation at 35 °C for 24 h. Assay of multiplex polymerase chain reaction (PCR) revealed that adulteration rate of bonito meat was 26.5% (9/34) in tuna candy samples. Tuna species in tuna candy samples was identified as Thunnus albacares for 29 samples (85.3%), Thunnus alalunga for four samples (11.8%) and Thunnus obesus for one sample (2.9%) by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP).     

Biogenic amines content,histamine-forming bacteria,and adulteration of pork and poultry in tuna dumpling products

Nine tuna dumpling products were purchased at nine retail markets in southern Taiwan. Occurrence of biogenic amines, histamine-forming bacteria, and adulteration of pork and poultry were determined. This study showed the high contents of aerobic plate count, total coliform and Escherichia coli in tested tuna dumpling products. Average content of various biogenic amines in all tested samples was less than 2.0 mg/100 g. Fifteen histamine-producing bacterial strains isolated from tested samples produced 8.7–466 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH). Assay of multiplex polymerase chain reaction (PCR) revealed adulteration rates were 88.9% (8/9) and 33.3% (3/9) for pork and poultry, respectively, in tuna dumpling. In addition, six samples of tuna dumpling meat were identified as Thunnus obesus, while other three samples were identified as Thunnus thynnus.