Monitoring sausage fermentation using an electronic nose

In this study a sensor array and pattern recognition routines (an electronic nose) were used to monitor a sausage fermentation in order to follow the changes in emitted volatile compounds during the fermentation process and to compare the electronic nose results with a sensory analysis. From the sensor array responses the fermentation time could be predicted using different methods, where principal component regression and an artificial neural network based on all sensors in the electronic nose performed best. A sensory panel evaluated the final product and these results were compared with the electronic nose measurements in the early stage of the process and on the final sausages. A principal component analysis showed that one of the sausage batches clearly deviated from the other using both the sensory panel data and the electronic nose responses. The deviating batch was different already after 4 h and the difference was consistent during the process. © 1998 SCI.     

电子鼻在食品工业中的应用

论述了电子鼻的产生背景、原理、结构、研究现状及其在食品工业中的应用。     

PVC薄膜味觉传感器阵列对调味品和软饮料的识别

以铂工作电极(PtE)为基底聚合吡咯(PPy),并在聚吡咯表面被覆不同味敏剂修饰的PVC薄膜,得到八支味觉传感器,并进而与217型双盐桥饱和甘汞电极构成味觉传感器阵列-8-PPP-TSA。采用开路电位法获取调味品和软饮料不同样品在各传感器界面的数据响应矩阵,数据矩阵使用主成分分析方法可将各样品属性的相似相异程度在二维得分图上得以直观表达,调味品被分为鲜、咸-鲜、咸、酸四个区,软饮料被大致分为甜、高酸低甜、高甜低酸三个区;根据各样本之间的欧氏距离大小,使用聚类分析方法作亲疏关系树形谱系图,在不同的相似度下可将众多样品依据亲疏关系远近进行有层次的味觉聚类区分,错判较少。此外,模式识别分析结果表明,8-PPP-TSA的仿生味觉识别具有与生物味觉识别相似的特点。     

High throughput non-destructive assessment of quality and safety of packaged food products using phosphorescent oxygen sensors

Intelligent and active packaging technologies have gained attention in recent time due to increased demand by the consumers and manufacturers for sustaining the quality and safety of food products, improved shelf-life as well as real time monitoring of the packaging, storage and handling processes. In this context, phosphorescence based sensors for molecular oxygen (O₂) are important tools for monitoring of packaged products, new product development and optimisation. They allow fast, reversible, real-time and quantitative monitoring of residual O₂ levels in a non-destructive manner, being superior over alternative systems. In this review, we describe the main types of phosphorescent O₂-sensitive materials, fabrication methods and general requirements for sensors for food packaging applications. The main developments and representative examples are provided which illustrate the application of such sensors for monitoring of gaseous and dissolved O₂ in various types of packaged foods and beverages. We also compare commercial O₂ sensing instrumentation and disposable O₂ sensors currently in use.     

Device for acoustic measurement of food texture using a piezoelectric sensor

We have developed a device that enables direct measurement of food texture. The device inserts a probe into a food sample and detects the vibration caused by the sample’s fracture. A piezoelectric sensor was used to detect that vibration. The frequency response of the piezoelectric sensor was measured. Results showed that the sensor covered the full audio frequency range up to 20 kHz. The device probe was designed so that its resonance was not in the signal detection band. An octave multi-filter was used to analyze the obtained signals. Preliminary data were obtained and used to quantify the sample texture. Quantification of food texture was possible by using the device together with the analytical tool. We also discuss the application of the device to investigation of physical and structural aspects of food.     

2019年济南食品中化学污染物及有害因素监测分析

摘要：目的 了解济南市2019年市售食品中化学污染物总体状况,及时发现食品安全隐患,为食品安全监管工作提供科学依据。方法 对全市12个区县的食品进行监测,按照《国家食品污染和有害因素风险工作手册》和国家标准方法进行检验、评价和分析。结果 2019共采集14类1505份样品,监测项目67种,超标率为4.8%（72/1505）。从不合格样品种类来看,肉及肉制品不合格率最高,为11.2%（19/170）,其次分别为食用菌和蔬菜,7.5%（6/80）、6.4%（21/330）。从不合格项目来看,铅、镉不合格率高于汞、砷;对硫磷、克百威等高毒农药在蔬菜中不合格率较高,分别为1.8%（6/330）、1.2%（4/330）;禁用药物克伦特罗在生畜肉内脏中不合格率最高为6.5%（11/170）;漂白剂二氧化硫在干食用菌中不合格率为5.0%（4/80）略高于面制品中食品添加剂不合格率4.1%。结论 济南市2019年总体状况良好,但仍然存在食品安全隐患。较为突出的问题为生畜肉及其内脏中“瘦肉精”类物质不合格率较高;面制品、干食用菌中违规超量使用食品添加剂;个别蔬菜中高毒农药项目不合格等,下一步仍需要加强隐患食品种类和项目的监测和监管,保障消费者的食品安全。     

Oxygen transfer in foods using oxygen luminescence sensors: Influence of oxygen partial pressure and food nature and composition

A rapid and easy to handle (on-line monitoring) method to achieve oxygen sorption kinetics was developed and tested on a large range of food products. Measurements were performed using luminescence sensors placed into of a thin layer of food material exposed to increasing oxygen contents in the atmosphere. From oxygen sorption kinetics diffusivity values could be calculated using a mathematical model based on Fick’s second law. A large range of model and real food were studied: water, agar gel, orange juice, mashed apple, mashed tomato, miglyol, olive oil and copra oil.     

我国食品理化实验室专业技术人员的食品安全知信行调查及影响因素分析

目的 了解我国食品理化实验室专业技术人员食品安全知识、态度、行为现状,探讨其影响因素。方法 对我国15个省的省级、市级、区（县）级部门下属食品理化实验室及第三方机构、企业等非政府机构食品理化实验室的专业技术人员开展食品安全知识、态度、行为问卷调查,并对调查结果进行统计分析。结果 共回收有效问卷1339份。除性别对态度得分无显著影响,文化程度、就职年限等对行为无显著影响外,年龄、实验室类型、所在区域和最近一次接受培训时间等均是影响食品理化检验人员食品安全知识、态度、行为得分的因素,且知识、态度和行为得分存在正相关关系。结论 尽管存在满分问卷,但食品理化实验室专业技术人员KAP平均得分仅略高于及格水平。需要关注重点人群,如年龄25岁以下、就职年限2年以下或大专及以下学历的专业技术人员等食品安全知识水平的提升、态度的端正和行为的规范。     

电子舌技术背景与研究进展

介绍了电子舌的概念、基本结构及其发展历史,重点讨论了电子舌系统的技术背景。电子舌通常由三大部分组成,一是传感器阵列,包括PVC薄膜传感器阵列、Langmuir-Blodgett修饰膜传感器阵列、硫属玻璃传感器阵列等;二是模式识别方法,如主成分分析法、人工神经网络法、偏最小二乘法、简单优劣判别分析法等;三是相关的专家自学习系统。还介绍了作者近年来研究实现的新型多频脉冲电子舌——智舌（Smartongue）系统,并对电子舌发展的整体方向和趋势作了展望,强调电子舌等智能感觉系统将成为分析科学及其它学科领域中一类具有广阔发展前景的思路与技术。     

Overview on liquid chromatographic analysis of tetracycline residues in food matrices

Tetracycline antibiotics (TCs) are often used as feed additives for food-producing animals because of the wide Gram (+) and Gram (−) antibacterial spectrum, low toxicity profile and more importantly low cost. However, antibiotic residues in food, produced from those animals, might be high due to misuse of TCs. Depending on the level of antibiotic residues, a negative impact on human health might be expected. The risk for public health resulting from the use of these veterinary medications has always been a though question to answer for health authorities around the world. Therefore, it is very important to determine residues of TCs in food accurately with appropriate analytical methods that are optimised, validated and implementing new advanced techniques. In this paper, liquid chromatographic methods that are available for the determination of TC levels in foods and food products are reviewed.     

Identification of anatoxins in blue-green algae food supplements using liquid chromatography-tandem mass spectrometry

Blue-green algae (cyanobacteria) in tablets and capsules, which are marketed as health food supplements, were investigated for the presence of neurotoxins related to anatoxin-a. These neurotoxins, which are nicotinic agonists, were investigated using isocratic micro-liquid chromatography-tandem mass spectrometry (micro-LC-MS-MS). The investigated compounds were anatoxin-a and homoanatoxin-a, together with their degradation products, dihydroanatoxin-a, epoxyanatoxin-a, dihydrohomoanatoxin-a and epoxyhomoanatoxin-a which were synthesized from the parent toxins. The analytes were extracted with methanol followed by isocratic chromatography on a micro C₁₈     

Estimation of iodine in food,food products and salt using ENAA

An epithermal neutron activation analysis (ENAA) method using boron carbide filter was standardised for the determination of low levels of iodine in various food and food products like milk, milk powder, baby food and health drink powders. The concentrations of iodine were also determined in seven samples of iodised salt used in cooking in India. Advantage of iodine determination by ENAA was evaluated by determining boron ratios of iodine and its interfering elements like Na, K, Mn, Cl and Br. Iodine concentrations were determined in seven biological reference materials obtained from NIST and IAEA, out of which three SRMs were used as the control samples. The results showed that trace levels of iodine can be determined in samples even in the presence of high salt content without chemical separations.     

电化学传感器在食品检测中的应用

食品安全问题一直以来都受到国家和人民的重点关注,寻找一种方便又精确的食品安全检测方法作为有效的监管工具就显得尤为重要,相较于传统的液相色谱法、质谱法等食品安全检测方法来说,电化学传感器由于其精度高、成本低、检测时间短、灵敏度高等优势在食品安全检测方面具有广阔的应用前景.本文对电化学传感器在食品中抗生素残留、添加色素、食...     

Detection of bacterial endotoxin in food: New planar interdigital sensors based approach

Food poisoning caused by endotoxins or Lipopolysaccharide (LPS) are associated with Gram-negative bacteria. Two major food-borne pathogens, Escherichia coli and Salmonella are examples of Gram-negative bacteria which cause a large number of outbreaks of food poisoning. New types of planar interdigital sensors have been fabricated with different coating materials to assess their response to endotoxins. A carboxyl-functional polymer, APTES (3-Aminopropyltriethoxysilane) and Thionine were chosen to be coated onto FR4 interdigital sensors. The chosen coating materials have carboxylic or amine functional groups, which were optimized to be stable in water. All coated sensors were immobilized with PmB (Polymyxin B) which has specific binding properties to LPS. The sensors were tested with different concentrations of LPS O111:B4, ranging from 0.1 to 1000 μg/ml. Analyses of sensors’ performance were based on the impedance spectroscopy method. The impedance spectra were modeled using a constant phase-element (CPE) equivalent circuit, and a principal component analysis (PCA) was used for data classification. Sensor coated with APTES has shown better selectivity for LPS detection. The experiments were repeated by coating APTES and immobilizing PmB to a new improve designed of novel interdigital sensors (thin film silicon based sensors). These sensors were observed to have better sensitivity and selectivity to the target biomolecules of LPS. Further experiments were conducted to study the effect of different coating thickness on sensor sensitivity, selectivity and stability. Different food samples contaminated with endotoxin were also tested to verify that the interdigital sensing approach is able to be used for endotoxin detection.     

Analysis of fumonisins in corn-based food by liquid chromatography with fluorescence and mass spectrometry detectors

The presented procedure involves an extraction with methanol–water, centrifugation and cleanup with immunoaffinity columns. A comparison study between fluorescence detector, mass spectrometry, and tandem mass spectrometry with a triple quadrupole (QqQ) analyzer using an electrospray ionisation interface for the determination of fumonisin B₁ and B₂ in corn-based products has been performed.     

中红外光谱与模式识别相结合鉴别茶叶种类

采用漫反射傅立叶变换红外（FTIR）光谱法结合主成分分析对苏州“碧螺春”、浙江“龙并”、安徽祁门红茶、福建“铁观音”4种茶叶进行了聚类分析。结果表明，主成分分析结合马氏距离判据的方法对上述4种茶叶可进行鉴别，该法快速、准确，为客观评价茶叶品种提供了一种新的方法。     

基于三维荧光光谱及模式识别技术对当归质量的分析与鉴别

利用荧光光谱分析技术,筛选供试品溶液制备和光谱分析测试条件,建立当归提取物三维荧光光谱质量分析和判别方法.研究结果表明,当归水提取物与50％甲醇-水提取物具有相似的三维荧光光谱,主要呈现出270 nm/345 nm、270 nm/475 nm和330 nm/475 nm三个特征激发/发射(λex/λem)峰,但特征峰的...     

Validation of a size exclusion liquid chromatographic method for determination of methylcellulose and hydroxypropyl methylcellulose food gums as soluble dietary fiber in food and food product

A size exclusion liquid chromatographic method was developed for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) as dietary fiber in food. These modified cellulose food gums are used in a wide variety of foods and physiologically behave as dietary fibers but are not determined using existing analytical dietary fiber methods. This article reports a single laboratory validation of a new method based on AOAC 991.43, and uses a liquid chromatograph with a refractive index detector. This new method was validated for foods containing 0.2–27% of MC and HPMC employing AOAC’s Single Laboratory Validation protocol. Ten food samples of meat, bread, milk powder, potato and orange juice drink mix were studied. Precision of the new method, measured as total standard deviation (St), varied from 0.01 to 2 for foods containing 0.2–27% MC; and from 0.05 to 0.2 for foods containing 0.5–3.8% HPMC. Recovery varied from 76% to 85% for MC, and from 75% to 113% for HPMC. Use of a blank matrix proved successful in correcting for indigenous food fibers. The method demonstrated excellent linearity down to 0.03%. This provides the sensitivity required for food nutrition labeling purposes. These results show the method is suitable for determination of MC and HPMC in food and support further validation through a collaborative study.