Rapid Detection of Pseudomonas in Seafoods Using Protease Indicator

The effects of Pseudomonas and the proteases it synthesizes in seafoods rendering them unfit for consumption are not fully recognized. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed wherein protease produced by Pseudomonas isolated from shrimp was used as antigen, and anti-protease IgG conjugated with alkaline phosphatase was the second antibody. Purified protease and seafood samples, naturally contaminated or artificially inoculated with Pseudomonas, were positive by ELISA. The conventional culture method took 3 days to complete, but ELISA detected Pseudomonas with in 24h. The rapidity, simplicity and efficacy of this test make it useful for implementation of HACCP systems.     

引起果蔬汁变质的微生物概述

微生物污染引起的果蔬汁变质是果蔬汁变质的重要原因之一。分别从细菌、酵母菌和霉菌等三个方面综述了引起果蔬汁变质的微生物种类、来源及特征。     

食源性腐败菌挥发性有机化合物的研究进展

食源性腐败菌是食品腐败的重要原因, 它可通过初级或次级代谢产生具有异味的挥发性有机化合物(volatile organic compounds, VOCs), 加速食品的腐败进程。腐败菌种类及组成会随食品基质和贮藏条件而改变, 导致产生的VOCs也具有多样性和差异性。随挥发性有机物质收集和检测技术的快速发展, 通过分析腐败菌相关的VOCs成分组成可鉴别食源性腐败菌种类和食物腐败进程。本文对常见腐败菌VOCs的产生途径和种类进行归纳, 并重点探讨了VOCs提取分析技术及在食品腐败研究中的具体应用, 为有效进行腐败菌防控, 提升食品质量和安全提供参考。     

新疆椒麻鸡中腐败细菌的分离与鉴定

为研究新疆椒麻鸡中腐败细菌的种类和特性,采用平板划线法分离腐败菌。利用生理生化实验和16S rDNA序列分析方法,对从椒麻鸡中分离的31 株腐败菌进行鉴定。结果表明：所筛选的31 株菌中,肠杆菌20 株、葡萄球菌3 株、气单胞菌2 株、乳酸菌4 株、溶酪大球菌2 株;新鲜椒麻鸡中的主要腐败菌为溶酪大球菌、葡萄球菌和肠杆菌;低温5 ℃贮藏条件下腐败样品中的主要腐败菌为乳酸菌、葡萄球菌和肠杆菌;常温25 ℃贮藏条件下腐败椒麻鸡中的腐败菌主要为肠杆菌、气单胞菌、葡萄球菌和乳杆菌。     

Postharvest ozone application for the preservation of fruits and vegetables

Vegetables and fruits have been recognized as a healthy and nutritive value food, with both a noticeable rise in consumption nowadays and greater frequency of foodborne illnesses associated with fresh produce. Current sanitation disinfectants fail to adequately control common spoilage microorganisms as well as potential harmful human pathogens. Alternative and effective disinfectants are being sought, with ozone being a viable alternative to traditional disinfectants. Despite the considerable commercial interest that ozone has attracted, several contradictions regarding the ozone efficiency are often found in the literature and further research is still needed to explore its potential application in the food industry as sanitizer.     

大豆浸泡过程中腐败微生物对豆浆品质的影响

通过对大豆浸泡过程中腐败微生物种类及数量开展研究,经致腐细菌回接实验进一步探明豆浆腐败现象与致腐细菌的关系,为豆浆稳定性控制及豆制品加工自动化提供依据。从大豆浸泡水中分离3 株优势菌DF-1、DF-2和DF-3,结合形态学及16S rDNA序列分析,分别鉴定为短稳杆菌、产气肠杆菌和乳酸乳球菌。将优势菌分别回接至灭菌豆浆,于25 ℃保藏12 h,理化指标结果表明3 种微生物对豆浆品质影响有较大差异：短稳杆菌产黄色素,在豆浆表面形成黄色菌膜并产生腐臭味;产气肠杆菌产酸产气,使豆浆形成蜂窝状凝乳,腐败变馊;乳酸乳球菌产酸使豆浆凝固。本研究为豆制品自动化生产过程中控制豆浆品质及加工稳定性提供参考。     

生鲜家畜肉类与水产鱼虾类物流过程中微生物菌相变化的研究进展

生鲜家畜肉类及水产鱼虾类物流过程中的腐败变质主要由微生物引起。随着分子生物学技术的快速发展,分子生态技术已成为研究生鲜家畜肉类及水产鱼虾类物流过程中微生物菌相变化的主要手段。引起生鲜家畜肉类及水产鱼虾类在物流过程中腐败变质的微生物也不断被发现。本文综述了生鲜家畜肉类及水产鱼虾类物流过程中常见微生物物种,包括肉食杆菌、乳酸菌、沙门氏菌属、假单胞菌属、明串珠菌属、热杀索丝菌、单增李斯特氏菌等细菌以及酵母菌、霉菌等真菌;介绍了2010年后多用于生鲜家畜肉类和水产鱼虾类菌相研究的分子生态技术,包括变性梯度凝胶电泳技术、末端限制性片段长度多态性技术、高通量测序技术和实时定量聚合酶链式反应技术,旨在为我国生鲜家畜肉类及水产鱼虾类的菌相研究提供参考。     

Determination of volatile compounds of precooked prawn (Penaeus vannamei) and cultured gilthead sea bream (Sparus aurata) stored in ice as possible spoilage markers using solid phase microextraction and gas chromatography/mass spectrometry

BACKGROUND: Solid phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) have been reported as useful techniques for analysing volatile compounds to monitor fish freshness. In this study, SPME/GC/MS was applied to cultured gilthead sea bream and precooked prawn stored in ice for 6 days in order to find possible markers of spoilage. Total volatile basic nitrogen (TVB‐N) was also determined as a common index of spoilage. RESULTS: The TVB‐N value at the end of the storage period for cultured gilthead sea bream (302.40 ± 8.50 mg kg^?1) was within the range of acceptability for edible fish (300–400 mg kg^?1) but could be considered at the beginning of spoilage. For precooked prawn the TVB‐N value at day 6 (863.04 ± 7.84 mg kg^?1) was not acceptable for human consumption. SPME/GC/MS identified 30 compounds in cultured gilthead sea bream and 49 compounds in precooked prawn. In particular, 3‐methyl‐1‐butanol, 2‐methylbutanal, 3‐methylbutanal and 3‐hydroxy‐2‐butanone increased during refrigerated storage both in the two species investigated here and in other species reported elsewhere and could be considered as markers of spoilage. CONCLUSION: This study confirmed that SPME/GC/MS can be considered an efficient method suitable for analysing the volatile compounds of both raw fish and fishery products in order to monitor loss of freshness. Copyright © 2008 Society of Chemical Industry     

Effect of enterocin AS-48 in combination with high-intensity pulsed-electric field treatment against the spoilage bacterium Lactobacillus diolivorans in apple juice

Enterocin AS-48 was tested in apple juice against the cider-spoilage, exopolysaccharide-producing strain Lactobacillus diolivorans 29 in combination with high-intensity pulsed-electric field (HIPEF) treatment (35 kV/cm, 150 Hz, 4 μs and bipolar mode). A response surface methodology was applied to study the bactericidal effects of the combined treatment, with AS-48 concentration and HIPEF treatment time as process variables. At subinhibitory bacteriocin concentrations, microbial inactivation by the combined treatment increased as the bacteriocin concentration and the HIPEF treatment time increased (from 0.5 to 2.0 μg/ml and from 100 to 1000 μs, respectively). Highest inactivation (4.87 logs) was achieved by 1000 μs HIPEF treatment in combination with 2.0 μg/ml AS-48. While application of treatments separately did not protect juice from survivors during storage, survivors to the combined treatment were inactivated within the following 24 h of storage, and the treated samples remained free from detectable lactobacilli for at least 15 days at temperatures of 4 °C as well as 22 °C. The combined treatment could be useful for inactivation of exopolysaccharide-producing L. diolivorans in apple juice.     

一种快速粮情检测仪应用试验

基于真菌代谢的基本原理,开发了一种快速粮情检测仪.采用该仪器对不同水分的实验室小麦样品和实仓小麦中CO2、湿度变化进行了研究.结果表明,小麦储藏过程中CO2浓度和湿度的变化与危害真菌的生长有明显的相关性,通过检测储藏小麦中CO2和湿度的变化可对小麦储藏真菌危害进行早期的检测.