肉品中脂肪检测技术研究进展

脂肪是食品中重要的营养成分,可供给能量和必需脂肪酸,可作为脂溶性维生素载体.肉品中脂肪含量与脂肪酸种类及其组成直接影响肉品的质量和风味.本文介绍动物油脂的相关概念,重点论述肉品中脂肪的提取与检测方法,以及气相色谱法、高效液相色谱法、薄层色谱法和红外光谱法在脂肪酸分析检测中的应用现状.     

Use of Volatiles as Indicators of Lipid Oxidation in Muscle Foods

Lipid oxidation has long been recognized as a leading cause of quality deterioration in muscle foods and is often the decisive factor in determining food product storage life. Lipid oxidation generates a number of products, including volatile compounds, which are the major contributors to the development of rancid off‐flavors and odors. Over the years, methodologies have been developed to quantify lipid oxidation products in muscle foods. This article reviews the analytical methods that have been used to quantify volatile compounds as indicators of lipid oxidation in muscle foods. The sampling methodologies of distillation/solvent extraction and headspace analysis, and isolation methods associated with gas chromatographic (GC) and high‐performance liquid chromatography (HPLC) analyses are discussed. Within gas chromatographic methodologies, headspace (HS) sampling (static HS, dynamic purge‐and‐trap HS techniques, and solid‐phase microextraction [SPME]) are addressed.     

A review: Current analytical methods for the determination of biogenic amines in foods

Analysis of biogenic amines (BA) in foods was reviewed. Biogenic amines are natural antinutrition factors and are important from a hygienic point of view as they have been implicated as the causative agents in a number of food poisoning episodes, and they are able to initiate various pharmacological reactions. Histamine, putrescine, cadaverine, tyramine, tryptamine, β-phenylethylamine, spermine, and spermidine are considered to be the most important biogenic amines occurring in foods. Analysis of BA is important because of their toxicity and their usage as indicators of the degree of freshness or spoilage of food. Several methods have been developed for determination of biogenic amines in food. The analytical methods used for quantification of BA are mainly based on chromatographic methods: thin layer chromatography (TLC), gas chromatography (GC), capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). HPLC is most often used for the analysis method of BAs. Due to low volatility and lack of chromophores of most BA, UV-spectrometric detectors cannot be used. The large majority of assays employs fluorimetric detection with precolumn or postcolumn derivatization techniques. This review shows that these methods allow quantitative determination of biogenic amines, individually or simultaneously in foods.     

Gas Chromatography‐Combustion‐Isotope Ratio Mass Spectrometry for Traceability and Authenticity in Foods and Beverages

As consumers demand more certainty over where their food and beverages originate from and the genuineness of ingredients, there is a need for analytical techniques that are able to provide data on issues such as traceability, authenticity, and origin of foods and beverages. One such technique that shows enormous promise in this area is gas chromatography‐combustion‐isotope ratio mass spectrometry (GC‐C‐IRMS). As will be demonstrated in this review, GC‐C‐IRMS is able to be applied to a wide array of foods and beverages generating data on key food components such as aroma compounds, sugars, amino acids, and carbon dioxide (in carbonated beverages). Such data can be used to determine synthetic and natural ingredients; substitution of 1 ingredient for another (such as apple for pear); the use of synthetic or organic fertilizers; and origin of foods and food ingredients, including carbon dioxide. Therefore, GC‐C‐IRMS is one of the most powerful techniques available to detect fraudulent, illegal, or unsafe practices in the food and beverages industries and its increasing use will ensure that consumers may have confidence in buying authentic products of known origin.     

Chemical composition of naturally fermented buttermilk

Naturally fermented buttermilk, prepared from soured cream or milk, was collected during two seasons from sixteen farms in northern Ethiopia, to study chemical composition and flavour compounds. Protein, fat, organic acids, carbohydrates and volatile compounds were quantified using Kjeldahl, Gerber, high‐pressure liquid chromatography (HPLC) and headspace GC methods, respectively. Widely differing concentrations of organic acids and volatile compounds among samples indicated variable fermentation in the products. This indicates the need for the introduction of the standardisation of the process to supply the market with homogenous buttermilk products.     

Techniques for the Analysis of Minor Lipid Oxidation Products Derived from Triacylglycerols: Epoxides,Alcohols, and Ketones

Lipid oxidation can lead to flavor and safety issues in fat‐containing foods. In order to measure the extent of lipid oxidation, hydroperoxides and their scission products are normally targeted for analytical purposes. In recent years, the formation of rarely monitored oxygenated products, including epoxides, alcohols, and ketones, has also raised concerns. These products are thought to form from alternative pathways that compete with chain scissions, and should not be neglected. In this review, a number of instrumental techniques and approaches to determine epoxides, alcohols, and ketones are discussed, with a focus on their selectivity and sensitivity in applications to food lipids and oils. Special attention is given to methods employing gas chromatography (GC), high‐performance liquid chromatography (HPLC), and nuclear magnetic resonance (NMR). For characterization purposes, GC‐mass spectrometry (GC‐MS) provides valuable information regarding the structures of individual oxygenated fatty acids, typically as methyl esters, isolated from oxygenated triacylglycerols (TAGs), while the use of liquid chromatography–MS (LC‐MS) techniques allows analysis of intact oxygenated TAGs and offers information about the position of the oxygenated acyl chain on the glycerol backbone. For quantitative purposes, traditional chromatography methods have exhibited excellent sensitivity, while spectroscopic methods, including NMR, are superior to chromatography for their rapid analytical cycles. Future studies should focus on the development of a routine quantitative method that is both selective and sensitive.     

食品中柠檬酸的检测方法研究进展

结合国内的研究进展,综述了食品中柠檬酸的各种检测方法。其中重点介绍了比较常用的测定方法,如高效液相色谱法、离子色谱法、气相色谱法、电泳法、分光光度法等,并建议采取有效方法进行检测。     

Polychlorinated biphenyl residues in food and human milk: determination of co-planar and mono-ortho substituted congeners

An analytical method is described for determining the residues of coplanar as well as mono-ortho substituted PCB congeners both exhibiting toxicological relevance, in foods of animal origin and in human milk. The unsophisticated procedure, convenient for routine analyses, includes the extraction of lipids, clean-up steps using liquid/liquid partition and column chromatography, fractionation of the congeners using HPLC on a special carbon column with an optimal gradient elution, and capillary column gas chromatography with electron capture or mass spectrometric detection. As preliminary results indicate, the low-chlorinated PCB technical products contribute more to the actual contamination of environment and foods than has been estimated so far. Obviously the co-planar congeners are accumulated during the food chain in a portion different from that found for the other congeners.     

动物源性食品中抗生素残留、耐药细菌的分布及耐药基因的水平传播

目的：调查动物源性食品中抗生素的残留、耐药细菌的分布及抗生素对耐药基因水平转移的影响。方法：利用盐析辅助液液萃取/高效液相色谱/串联质谱法对市售动物源性食品中18种抗生素的含量进行检测;对样品中的需氧菌进行分离鉴定,利用PCR技术调查耐药基因的分布,通过接合转移试验调查抗生素胁迫对耐药基因水平传播的影响。结果：50份动物源性食品中检出环丙沙星、恩诺沙星、土霉素、金霉素、磺胺嘧啶和磺胺二甲嘧啶。162株分离株中磺胺甲基异恶唑耐药基因sul1的检出率最高。在环丙沙星胁迫下,三株供体菌中耐药基因qnrS的接合转移率均高于对照组。结论：动物源性食品中喹诺酮类、磺胺类和四环素类抗生素均有不同程度的残留。亚抑菌浓度抗生素促进耐药基因的接合转移。     

Application of Chromatographic Techniques in the Detection and Identification of Constituents Formed during Food Frying: A Review

Frying is one of the most popular food processing methods. However, many physicochemical reactions occur during frying, forming complex products in both the frying oil and the fried food. Chromatographic techniques have been successfully applied to characterize the products formed during food‐frying or during a simulated frying process. In this review, the specific products analyzed by gas chromatography (GC) and high‐performance liquid chromatography (HPLC) are elucidated in detail. The most studied components are polar compounds (such as volatile compounds, hydrolysis products, oxidized triacylglycerol [TAG] decomposition products, oxidized TAG monomers, sterol oxides, oxygenated TAG polymers, and acrylamide) and nonpolar compounds (such as cyclic fatty acid monomers and trans isomers), which are classified based on their polarity. However, the definite structures of TAG polymers and sterol oxides, and polymers analyzed by GC or HPLC‐based methods are only investigated in modeled reactions. Furthermore, some of the sample pretreatments and chromatographic methods are only used to analyze the known products. A number of earlier trace amounts of undetected products need to be investigated by more effective detection techniques. The development of multidimensional chromatographic techniques and elaborate mass spectrometry detectors makes composition analysis possible for the food‐frying process, which may effectively promote the development of quality monitoring and nutrition evaluation for the fried foods.     

食品中硒的有机形态分析研究进展

硒是人体必不可少的微量元素, 不同形态的硒对人体的功能不同, 其中有机硒在抗氧化、抗癌、抗病毒、提高免疫力等方面对人体有重要作用。人体获取硒的途径主要通过膳食摄取, 如食用天然富硒食品、人工合成有机硒产品及有机硒强化剂等。市场上的富硒食品质量参差不齐, 为合理地评价食品中硒的摄入形态和水平, 对食品中硒的形态及含量的检测是近年来研究的一个重点。本文对食品中有机硒检测分离、形态分析以及含量测定等进行了综述, 并对以液相萃取法和酶解法为主的分离方法, 以气相色谱-电感耦合等离子体质谱法(gas chromatography-inductively coupled plasma spectrometry, GC-ICP-MS)、高效液相色谱-电感耦合等离子体质谱法(high performance liquid chromatography-inductively coupled plasma spectrometry, HPLC-ICP-MS)、高效液相色谱-串联三重四级杆质谱法(high performance liquid chromatography-tandem mass spectrometry, HPLC-MS/MS)以及电泳-电感耦合等离子体质谱法(capillary electrophoresis-inductively coupled plasma spectrometry, CE-ICP-MS)为主的检测方法等研究进展进行了总结, 以期对食品中有机硒的检测提供相应的理论依据, 促进食品中有机硒检测标准的发展。     

A review of the liquid chromatographic methods for the determination of biogenic amines in foods

Biogenic amines (BAs) are biologically active molecules which have aliphatic (putrescine, cadaverine, spermine, spermidine), aromatic (tyramine, phenylethylamine) or heterocyclic (histamine, tryptamine) structures. They can be detected in raw and processed foods which are formed and degraded through several pathways during the metabolic processes of animals, plants and microorganisms. The identification and quantitation procedures of BAs in food samples are very important, because BAs are considered as the indicators of food quality and freshness. The determination of BAs are commonly achieved by separation techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC) and capillary electrophoresis (CE). In this article, analysis of BAs in foods were reviewed from 2007 to present.     

Validation of bacterial growth inhibition models based on molecular properties of organic acids

Organic acids occur naturally in foods and have been used in many food products as preservatives because they inhibit the growth of most microorganisms. The acids commonly found in foods differ greatly in both their structure and inhibitory effects for different bacteria. A way to represent relationships between different acids was previously described in which principal components analysis (PCA) was applied to 11 physical and chemical properties of 17 organic acids, to arrive at principal properties. These were used for development of regression models that related the minimum inhibitory concentrations (MICs) of organic acids to their principal properties. Separate MIC models were constructed for six different bacteria. The objective of the present study was to test the predictive capabilities of the organism models using different organic acids from the ones used to construct the original models. MIC predictions were made for three acids for each of the six bacteria for which models were previously constructed. MIC determinations for these acids were then carried out and compared with the predictions; these were in good agreement, thus validating the models. The new data were combined with that obtained previously to produce similar, but slightly stronger models. These had R(2) values between 0.861 and 0.992.     

Effects of light on growth,levels of anthocyanin,concentration of metabolites in Fagopyrum tataricum sprout cultures

Tartary buckwheat (Fagopyrum tataricum) sprouts are a popular healthy product around the world. The purpose of this study was to investigate the effects of light on growth, levels of anthocyanin, metabolite concentration in tartary buckwheat sprouts. To investigate the metabolites and accumulation of anthocyanin in tartary buckwheat sprouts, gas chromatography‐mass spectrometry (GC‐MS) and high performance liquid chromatography (HPLC) were conducted. The levels of Cyanidin 3‐O‐glucoside and Cyanidin 3‐O‐rutinoside were higher under light/dark condition than that under dark condition. A total of fifty‐five metabolites, including nineteen amino acids, fifteen organic acids, eight sugars, four amines, two sugar alcohols, seven other kinds were detected in tartary buckwheat sprouts. Multivariate statistical methods were used to fully distinguish between light/dark and dark condition, and eleven compounds were defined as deferentially expressed metabolites using these methods. Our results may be helpful for practical application in the production of nutritional buckwheat sprouts in the future.     

Formation of furan in baby food products: Identification and technical challenges

Furan is generally produced during thermal processing of various foods including baked, fried, and roasted food items such as cereal products, coffee, canned, and jarred prepared foods as well as in baby foods. Furan is a toxic and carcinogenic compound to humans and may be a vital hazard to infants and babies. Furan could be formed in foods through thermal degradation of carbohydrates, dissociation of amino acids, and oxidation of polyunsaturated fatty acids. The detection of furan in food products is difficult due to its high volatility and low molecular weight. Headspace solid-phase microextraction coupled with gas chromatography/mass spectrometer (GC/MS) is generally used for analysis of furan in food samples. The risk assessment of furan can be characterized using margin of exposure approach (MOE). Conventional strategies including cooking in open vessels, reheating of commercially processed foods with stirring, and physical removal using vacuum treatment have remained unsuccessful for the removal of furan due to the complex production mechanisms and possible precursors of furan. The innovative food-processing technologies such as high-pressure processing (HPP), high-pressure thermal sterilization (HPTS), and Ohmic heating have been adapted for the reduction of furan levels in baby foods. But in recent years, only HPP has gained interest due to successful reduction of furan because of its nonthermal mechanism. HPP-treated baby food products are commercially available from different food companies. This review summarizes the mechanism involved in the formation of furan in foods, its toxicity, and identification in infant foods and presents a solution for limiting its formation, occurrence, and retention using novel strategies.     

Organic Acids and Meat Preservation: A Review

Despite the application of various preservation methods, many problems are still encountered as a result of food spoilage and food poisoning. There is increasing demand for foods produced with milder treatments, and the movement towards more natural and even certified organic foods has been the fastest growing sector of the food industry over the last decade. The interest in bio-preservation of food systems has necessitated the development of new natural antimicrobial compounds from different origins, and in response to modern consumer trends and food legislation, the food industry is faced with serious challenges. Both conventional and organic modes of production are at risk of contamination, but it is possible that organic food might present a bigger problem. Organic acids have been of considerable value as food preservatives since they are also food ingredients and often naturally produced by microorganisms. However, limited data on their effects in commercial practice are available, and despite regulatory approval, organic acids are not widely accepted in commercial practice, and in particular in meat decontamination.

Susceptibility of microorganisms to the most currently used preservatives has been decreasing, and there is concern that decontamination with organic acids could result in the emergence of acid-tolerant food-borne pathogens, evolving to overcome the protective barrier of the human gastric stomach. In the evaluation and integration of new processing/preservation treatments, research objectives would have to include the identification of specific targets of organic acids—understanding the molecular mechanisms that confer high level resistance and analysing pathogen response to antimicrobials. This article provides an overview of various studies done on organic acids as preservatives and highlights aspects such as application, antimicrobial action, and future prospects. Other important issues, such as the application of functional genomics in developing new preservation methods, resistance development, and conventional laboratory procedures are also discussed.     

Analytical Methods for Quantification of Modified Fatty Acids and Sterols Formed as a Result of Processing

Fats and oils are often submitted to technological treatments before being consumed. Some treatments like refining, hydrogenation, and frying often lead to the formation of modified fatty acids such as cyclic fatty acid monomers (CFAM), geometrical fatty acid isomers, and/or oxidized fatty acids and sterols (cholesterol and phytosterols). Both cholesterol oxidation products (COP) and phytosterol oxidation products (POP), may be present in foods. As some of the newly formed components may present some adverse effects upon consumption, methods have been developed to analyze these compounds in food products and biological samples. Gas liquid chromatography (GC) on long polar columns (100m) is a good choice to quantify trans mono- and poly-unsaturated fatty acids. In some cases a pre-fractionation step using silver nitrate thin layer chromatography (AgNO₃-TLC) may be necessary to avoid GC overlapping of cis and trans isomers. Analysis of CFAM usually involves transformation of the sample in fatty acid methyl esters (FAME) which after addition of an internal standard (IS) are further hydrogenated. An enrichment step using reverse phase high performance liquid chromatography (RP-HPLC) permits to obtain a fraction which consists of a mixture of CFAM and the IS. This fraction is further analyzed by GC on a polar column. The analysis of oxidized triacylglycerol monomers (oxTG) as a group was feasible by a combination of adsorption and size-exclusion chromatography. Quantification in used frying fats and oils around the limit of rejection for human consumption (25% polar compounds) has shown that the amount of oxTG range 5.9–9.4% expressed on fat or oil weight. In foods and biological tissues, the level of oxidized sterols (SOP) is often a very small fraction of their unoxidized forms. Analysis of SOP involved extraction of lipids, saponification or transesterification, enrichment, and subsequent qualitative and quantitative determination by GC and GC-MS, or HPLC and HPLC-MS. In addition, enrichment of SOP requires complete separation from the unoxidized sterols in order to separate these compounds even by high resolution GC capillary columns.     

Quality of plant products from organic agriculture

During the last decade, consumers' trust in food quality has decreased drastically, mainly because of growing ecological awareness and several food scandals (e.g. BSE, dioxins, bacterial contamination). It has been found that intensive conventional agriculture can introduce contaminants into the food chain. Consumers have started to look for safer and better controlled foods produced in more environmentally friendly, authentic and local systems. Organically produced foods are widely believed to satisfy the above demands, leading to lower environmental impacts and higher nutritive values. So far, studies have partly confirmed this opinion. Organic crops contain fewer nitrates, nitrites and pesticide residues but, as a rule, more dry matter, vitamin C, phenolic compounds, essential amino acids and total sugars than conventional crops. Organic crops also contain statistically more mineral compounds and usually have better sensory and long‐term storage qualities. However, there are also some negatives: plants cultivated in organic systems generally have 20% lower yields than conventionally produced crops. Several important problems need to be addressed in the coming years: environmental, bacterial and fungal contamination of organic crops and, the most essential issue, the impact of organic food consumption on animal and human health. Copyright © 2007 Society of Chemical Industry     

A review of methodology for the analysis of pyrethrin and pyrethroid residues in food of animal origin

Pyrethrin and pyrethroid pesticides are commonly used in crop protection and animal health, to control pests. As a result, they can potentially transfer into food if good agricultural practice is not followed or even due to accidental contamination. The analysis of these compounds has been widely reported in crops and the environment. However, the analysis of pyrethrin and pyrethroids has not been reported frequently in foods of animal origin, particularly animal tissues. The focus of this review is to report on pyrethrin and pyrethroid analysis including key aspects such as chemistry, choice of target matrix, sample preparation, chemical analysis, legislation and method validation. This review shows that most methodologies for the analysis of these compounds are based on gas chromatography with the trend in recent years to move towards GC-MS or GC-MS/MS based platforms. This review shows that these compounds can also be satisfactorily analysed by LC-MS/MS, which can be advantageous because of shorter chromatographic run times. A wide range of sample preparation procedures have been applied in analytical methods and more complex protocols are required for GC applications, whereas more crudely prepared extracts can be analysed by LC-MS/MS. This review demonstrates that pyrethrin and pyrethroid residues should be included as analytes in multi-class analytical methods for pesticides and veterinary drug residues in animal derived foods.     

Organic Acids and Meat Preservation: A Review

Despite the application of various preservation methods, many problems are still encountered as a result of food spoilage and food poisoning. There is increasing demand for foods produced with milder treatments, and the movement towards more natural and even certified organic foods has been the fastest growing sector of the food industry over the last decade. The interest in bio-preservation of food systems has necessitated the development of new natural antimicrobial compounds from different origins, and in response to modern consumer trends and food legislation, the food industry is faced with serious challenges. Both conventional and organic modes of production are at risk of contamination, but it is possible that organic food might present a bigger problem. Organic acids have been of considerable value as food preservatives since they are also food ingredients and often naturally produced by microorganisms. However, limited data on their effects in commercial practice are available, and despite regulatory approval, organic acids are not widely accepted in commercial practice, and in particular in meat decontamination.

Susceptibility of microorganisms to the most currently used preservatives has been decreasing, and there is concern that decontamination with organic acids could result in the emergence of acid-tolerant food-borne pathogens, evolving to overcome the protective barrier of the human gastric stomach. In the evaluation and integration of new processing/preservation treatments, research objectives would have to include the identification of specific targets of organic acids—understanding the molecular mechanisms that confer high level resistance and analysing pathogen response to antimicrobials. This article provides an overview of various studies done on organic acids as preservatives and highlights aspects such as application, antimicrobial action, and future prospects. Other important issues, such as the application of functional genomics in developing new preservation methods, resistance development, and conventional laboratory procedures are also discussed.