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排序方式: 共有1469条查询结果,搜索用时 31 毫秒
61.
Eleven major phenolic compounds (hyperoside, isoquercitrin, chlorogenic acid, ideain, epicatechin, two procyanidin (PA) dimers, three PA trimers and a PA dimer-hexoside) were quantified in the fruits of 22 cultivars/origins of three species of the Chinese hawthorn (Crataegus spp.) by HPLC–ESI-MS-SIR. Hyperoside (0.1–0.8 mg/g dry mass [DM]), isoquercitrin (0.1–0.3 mg/g DM), chlorogenic acid (0.2–1.6 mg/g DM), epicatechin (0.9–11.7 mg/g DM), PA B2 (0.7–12.4 mg/g DM), PA dimer II (0.1–1.5 mg/g DM), PA trimer I (0.1–2.7 mg/g DM), PA trimer II (0.7–6.9 mg/g DM), PA trimer III (0.01–1.2 mg/g DM) and a PA dimer-hexoside (trace–1.1 mg/g DM) were detected in all the samples. Ideain (0.0–0.7 mg/g DM) was found in all the samples except Crataegus scabrifolia. Significant correlations between the contents of individual PA aglycons were observed (r > 0.9, P < 0.01). A strong correlation between flavonols was also shown (r = 0.71, P < 0.01). Fruits of Crataegus pinnatifida var. major had higher contents of PAs but lower contents of flavonols compared with Crataegus brettschneideri. The fruits of C. scabrifolia contained the highest level of PA dimer-hexoside, which was present in trace amounts in the fruits of C. pinnatifida. 相似文献
62.
63.
目的建立多重实时荧光定量PCR(multiplex quantitative real-time PCR,multiplex qPCR)快速检测奶粉中金黄色葡萄球菌、沙门氏菌和克罗诺杆菌3种常见致病菌的方法。方法筛选目标菌株的特异性引物与探针,优化反应体系,建立稳定的多重q PCR反应体系。通过阳性菌株加标的方式验证体系的特异性,并确定人工污染奶粉的检出限。结果各对引物探针对目标菌株均能扩增,多重实时荧光PCR未发现交叉反应,对17株非目标菌进行检测均未检出,人工污染奶粉中克罗诺杆菌和沙门氏菌的检出限均为10~3 CFU/mL,金黄色葡萄球菌的检出限为10~4 CFU/mL。结论本研究方法可实现婴幼儿奶粉样品中3种致病菌qPCR高效率检测。 相似文献
64.
Siyuan Zhou Shiowshuh Sheen Yu‐Hsin Pang LinShu Liu Kit L. Yam 《Journal of food science》2013,78(5):M725-M730
Salmonella contamination on raw shrimp is a big food safety concern in the United States currently. This research evaluated the inhibition effects of vapor phase thymol, modified atmosphere (MA), and their combination against Salmonella spp. on raw shrimp. Growth profiles of a Salmonella spp. cocktail (6 strains), inoculated onto the surface of raw shrimp, treated with vapor phase thymol at 3 levels (0, 0.8, and 1.6 mg/L), or MA (59.5% CO2 + 39.5% N2 + 1% O2), both alone and in combination, at 3 temperatures (8, 12, and 16 ºC), were determined. Lag time and maximum growth rate of Salmonella spp. under each treatment were obtained using Baranyi and Roberts models. Results indicated that both vapor phase thymol and MA treatments alone inhibited the growth potential of Salmonella spp. effectively, extending the lag time by 10% to 100% and reducing the maximum growth rate by 14% to 71% compared with controlled samples at experimental temperatures (8, 12, and 16 ºC). Combination treatments of vapor phase thymol and MA exhibited greater inhibition effectiveness than each individual treatment and a synergistic antimicrobial effectiveness could be observed on the lag time extension. To the maximum, at 12 ºC, lag time of Salmonella spp. was extended 59.6% more by the combination treatment of 0.8 mg/L thymol + MA (36.97 h) than those effects combined from 0.8 mg/L thymol treatment and MA treatment alone (23.16 h in total). This combination strategy could be potentially utilized for Salmonella inhibition during the long distance and temperature‐abused raw shrimp import process. Practical Application The vapor phase thymol + MA combination strategy could be potentially applied in temperature‐abused and long‐distance raw shrimp import process to retard the Salmonella spp. growth, therefore reducing its import rejection rate as well as enhancing its food safety level to the consumers’ concerns. 相似文献
65.
研究湿粉(湿米粉及淀粉制品)加工过程中浸泡和洗米工艺对椰毒假单胞菌酵米面亚种的清除作用。模拟米样品污染椰毒假单胞菌酵米面亚种,36℃培养72 h后,在米表面形成菌膜,再模拟目前湿粉生产过程中浸泡和洗米工艺方式(静态浸泡清洗和动态缓慢搅拌清洗)进行处理,联合采用微生物检测技术、动物毒力测试和液相色谱-质谱/质谱检测技术,考察浸洗米工艺对椰毒假单胞菌酵米面亚种污染传递的防控效果。研究结果表明,静态浸洗和缓慢搅拌清洗都可以清除部分椰毒假单胞菌酵米面亚种,但无法保证完全洗去,存在风险向下一环节传递的可能性。针对湿粉生产加工工艺的特点,建议在湿粉生产过程中应严格执行原料米的浸泡和清洗,同时应加强班后对生产场所的清洁消毒,才能有效防控椰毒假单胞菌酵米面亚种污染的风险。 相似文献
66.
Microbial enhanced oil recovery (MEOR) applies biotechnology to improve residual crude oil production from substratum reservoir. MEOR includes in-situ MEOR and ex-situ MEOR. The former utilizes microbial growth and metabolism in the reservoir, and the latter directly injects desired active products produced by microbes on the surface. Taking biosurfactant-producing strain Pseudomonas aeruginosa WJ-1 for research objects, in-situ enhanced oil recovery and ex-situ enhanced oil recovery by biosurfactant-producing strain WJ-1 were comparatively investigated in sand-pack columns.The results showed that P.aeruginosa WJ-1 really proliferated in sand-pack columns, produced 2.66 g/L of biosurfactant, altered wettability, reduced oil-water interfacial tension (IFT) and emulsified crude oil under simulated in-situ process. Results also showed that higher biosurfactant concentration, lower IFT, smaller average diameters of emulsified crude oil were obtained in in-situ enhanced oil recovery experiment than those in ex-situ enhance oil recovery experiment. Similar wettability alteration was observed in both in-situ and ex-situ enhanced oil recovery experiment. The flooding experiments in sand-pack columns revealed that the recovery of in-situ was 7.46%/7.32% OOIP (original oil in place), and the recovery of the ex-situ was 4.64%/4.49% OOIP. Therefore, in-situ approach showed greater potential in enhancing oil recovery in contrast with ex-situ approach. It is recommended that the stimulation of indigenous microorganisms rather than injection of microbial produced active products should be applied when MEOR technologies were employed. 相似文献
67.
Toxic cyanobacterial blooms in a shallow, artificially mixed urban lake in Colorado, USA 总被引:2,自引:0,他引:2
P. J. Oberholster A.-M. Botha T. E. Cloete 《Lakes & Reservoirs: Research and Management》2006,11(2):111-123
One of the most severe problems associated with eutrophication of urban freshwater ecosystems is the occurrence of increasingly frequent blooms of toxic cyanobacteria. Cyanotoxins might accumulate in the trophic web, producing diverse intoxication symptoms and chronic effects that are difficult to diagnose and prevent. High mortality of domestic animals and fish has been reported previously under these prevailing conditions. This study investigates the taxonomic composition of phytoplankton assemblages in Sheldon Lake during the summer of 2004, a year after the completion of a restoration project on the lake. The study analysed the physical and chemical changes caused by urban run‐off and artificial mixing, as well as the usefulness of microcystin molecular markers derived from the mcy gene cluster for the detection of toxic cyanobacterial strains in environmental samples from Sheldon Lake. This study clearly demonstrates that the artificial mixing rate alone was insufficient to cause a transition to a well‐mixed aquatic system, and that cyanobacteria remained dominant throughout the summer months. The presence of toxic cyanobacterial strains was confirmed with the use of molecular markers that detected the presence of the mcy gene cluster responsible for the production of toxin by Microcystis spp. This approach might have a great potential use in the routine analyses of urban aquatic ecosystems. It also might make toxicity monitoring more feasible, allowing for the early application of corrective actions, especially for cases such as Sheldon Lake, which is a public recreational focal point. 相似文献
68.
Thalita Marques Passos Lívia Helena Moreira da Silva Leonardo Marmo Moreira Renato Amaro Zângaro Roberto da Silva Santos Fernanda Barrinha Fernandes 《臭氧:科学与工程》2014,36(2):138-143
Giardia spp. is a flagellate protozoan that presents two evolution forms, cysts and trophozoites. Cysts are resistant to chlorine, the most employed disinfectant agent in the treatment of water. For this reason, new techniques for the disinfection of waters that contain this parasite are necessary. This work evaluated the efficiency of the disinfection by ozone and ultrasound individually and simultaneously upon wastewater. The data obtained showed that after application, ozone, ultrasound, and combined techniques induced a significant elimination of Giardia spp. cysts. Furthermore, this effect was more accentuated when the two techniques were applied simultaneously. 相似文献
69.
70.
Abstract In this article, biosurfactant production from low-cost and renewable substrate and its application in petroleum industry were studied. Pseudomonas aeruginosa DG30 grew on used vegetable oil and accumulated 15.56 g/L of biosurfactant at 72 hr. The biosurfactant exhibited excellent surface activity and stability. Sand package tests showed an approximately 20% increase of oil recovery by the treatment of bacterial culture broth. Single-well stimulation tests were conducted in a heavy oil reservoir in Dagang Oilfield, Tianjin, China. The blockages in the wellbore areas were removed effectively and more than 616 tons of crude oil was enhanced. 相似文献