Review of analytical methods to measure boar taint compounds in porcine adipose tissue: the need for harmonised methods

This comprehensive review describes the analytical methods developed for quantification of the boar taint compounds skatole and androstenone in porcine adipose tissue. The following parts are considered; sampling, sample preparation, calibration and instrumentation. Additionally, method performance characteristics and level of validation of the existing methodology are discussed. It is concluded that there is a need for further validation of existing methods and need for standardisation of methodology to quantify boar taint compounds. Facing a possible near future ban of castration of male piglets would enforce further method harmonisation in this field.     

水果过敏原定量方法研究进展

随着水果消费种类与数量的增加以及相关花粉过敏的大流行,水果过敏问题日益凸显。水果过敏的预防与诊治对过敏原定量方法的灵敏度、精确性和稳健性提出了更高的要求。本文首先简述了水果过敏及其免疫学机制,对常见水果已鉴定的过敏原分子进行了蛋白家族汇总,介绍了5个主要蛋白家族（PR-10蛋白家族、类甜蛋白、非特异性脂质转移蛋白、抑制蛋白和几丁质酶）的生化性质和相关临床症状。其次,对水果过敏原定量应用最多的酶联免疫吸附法(enzyme-linked immunosorbent assay, ELISA)和液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry, LC-MS/MS)进行综述,分析了二者的优缺点及其在水果过敏原定量检测中的应用。最后,总结了水果过敏原定量的研究现状,并结合新兴技术指出未来研究方向,为水果过敏的临床诊断与防治提供参考。     

Revised method for quantitating dietary fibre components

A modification to existing methods of fibre separation and quantification has been proposed. The scheme involves lipid removal with diethyl ether; removal of water-soluble components and quantification of water-soluble fibre components; removal of water-insoluble starch; protein removal; pectin analyses; water-insoluble hemicellulose quantification; cellulose quantification; and lignin quantification. Simultaneous equations were used to compensate for hexose absorption at the same wavelength as pentoses. Recovery values for individual steps ranged from 90% using a low methoxy pectin to 98% using cornstarch, cellulose, agar or carrageenan. The scheme was used to analyse fibre components in seven wheat brans, maize bran, oat bran, soya bean hulls, potato and apple. Recoveries of fibre and other proximate analyses ranged from 95.9 to 104.7%. Remaining methodological problems are also discussed.     

细菌中蛋白质样品制备方法研究进展

细菌在生长繁殖时,细菌蛋白的表达受到环境影响而存在较大差异,使得细菌蛋白表达具有复杂性.在食品生产加工过程中可能会受到致病菌污染,细菌产生的内毒素和外毒素均会对人体健康构成威胁,因此需要高灵敏度和高特异性的检测方法来定量分析和鉴定食品中的细菌毒素.蛋白组学方法可以揭示细菌蛋白组成及其潜在的生物学功能,感染过程中菌体蛋白...     

近红外光谱结合化学计量法快速无损鉴别燕麦

提出了一种基于近红外光谱技术与化学计量学的燕麦无损鉴别方法。通过近红外光谱仪测定了5个品牌与劣质燕麦的光谱曲线,利用连续小波变换方法对光谱进行预处理,然后基于标准偏差与相对标准偏差的变量筛选方法筛选出具有代表的15个波数点,最后结合主成分分析法对不同燕麦样品快速鉴别。结果表明:连续小波变换可以有效地消除光谱中的背景干扰,提取光谱有效信息,波长筛选方法可以大大提高主成分分析结果的鉴别能力。通过结合近红外光谱分析技术与化学计量学方法,可对中国国产品牌、进口品牌和劣质燕麦进行准确鉴别。     

全谷物饮品稳定性的多尺度表征方法

随着全谷物健康认知和科学饮食概念的普及,消费者越来越关注形式各异的全谷物食品。全谷物饮品作为全谷物食品中的一种重要产品形式,其物理稳定性是研究开发过程中面临的主要挑战。由于全谷物饮品是一种以水为连续相,以淀粉、膳食纤维、蛋白质等为分散相的多相浊状液热力学不稳定体系,其分离速度快,严重影响消费者的可接受度。通过文献梳理,总结了全谷物饮品稳定性的宏观、介观、微观、纳观等多尺度表征方法及特征化学组分的表征方法,期望能为全谷物饮品的开发提供方法指导,特征化学组分助力全谷物食品的快速发展。     

Comparison of four methods to enumerate probiotic bifidobacteria in a fermented food product

Four methods of enumeration were compared by monitoring levels of probiotic bifidobacteria in fermented oat drink during storage. Strains of Bifidobacterium longum and B. lactis were quantified by plate counts, fluorescent in situ hybridization (FISH), quantitative real-time PCR and commercial LIVE/DEAD BacLight bacterial viability kit, and the methods were further developed to suit the enumeration of bifidobacteria in fermented foods. Plate counts of both B. lactis and B. longum were lower than the PCR and FISH counts. The LIVE/DEAD counts of B. lactis were comparable to PCR and FISH counts. The plate counts of B. lactis were slightly but significantly lower than LIVE/DEAD counts, suggesting that the cells that were not able to grow on plates may have become dormant. The plate counts of B. longum were several log units lower than LIVE/DEAD counts, suggesting that a remarkable part of the cells were dormant. Real-time PCR and FISH were shown to suit the quantification of the total amount of probiotic bifidobacteria in foods. Plate counts and LIVE/DEAD counts provided conflicting information on viability especially in the case of B. longum. We conclude that the choice of enumeration method for probiotic bacteria may have significant effect on the results of the analysis. The strain-specific properties and the objects of the analysis should be taken into account when enumeration methods for different probiotic strains are chosen.     

Effects of succinylation and deamidation on functional properties of oat protein isolate

The effects of two different modification methods (deamidation and succinylation) on the functional properties (solubility, water- and oil-binding capacity, foaming capacity and stability, emulsion activity and stability) of oat protein isolates were evaluated. Protein isolates extracted from defatted oat flour at alkaline pH were acylated by 0.20 g/g of succinic anhydride. The protein isolate was also modified using a mild acidic treatment (HCl, 0.5 N). Succinylation and deamidation improved solubility and emulsifying activity of the native protein isolate. Foaming capacity of oat protein isolate increased after deamidation, whereas succinylation decreased it. The deamidated and succinylated proteins had lower foam and emulsion stabilities than had their native counterpart. Water- and oil-binding capacity, in both modified oat proteins, was higher than those of the native oat protein isolate.     

天然燕麦中维生素B12的测定中2种微生物法前处理方式的比较

目的研究使用微生物法对燕麦中维生素B_(12)测定的可行性。方法以国标法为基础,采用标准前处理方式和添加淀粉酶的前处理方式分别对6份燕麦中的维生素B_(12)进行测定,比较2种不同前处理方式对检测结果的影响。结果国标法测定的标准曲线在维生素B_(12)的浓度为0.01~0.1 ng范围内具有良好的线性关系(r2=0.995)。前处理过程中加入20 m L浓度为1%的α-淀粉酶溶液可充分提取出燕麦样品中的维生素B_(12)。标准处理法的最大相对标准偏差(relative standard deviation,RSD)为10.2%,酶解处理法最大RSD为8.83%。结论对于燕麦中维生素B_(12)的测定,酶解处理法有更好的适用性,检测结果更为可靠。     

A review of methods used for investigation of protein–phenolic compound interactions

Interactions between the different compounds present in foods are common and have influence on the nutritional and functional properties of food products. Among a wide range of these interactions, the formation of complexes between proteins and phenolic compounds seems to be the most important issue. Complexation of the phenolic compounds with proteins can be analysed considering several aspects. These complexes might strongly affect nutritional potential of polyphenols by masking their antioxidant capacity, and on the other hand might have influence on the structure of proteins which may cause their precipitation or decrease susceptibility to digestion. The complexity of protein–phenolic compound interactions is a challenge for food analysts and forced researchers to establish a wide range of analytical methods, allowing determination of complexes formation. The main aim of this review is to give researchers an overview of the currently used methods that can be applied to study the interactions between proteins and phenolic compounds.     

Some methods for isolation and assays of enzymes occurring in cereals and legumes

Abstract

This review deals with isolation techniques and enzymatic assays which are applicable to the study of enzymes occurring in cereals and legumes. In the section of the paper concerned with separation and purification methods, various types of Chromatographic and electrophoretic techniques are described and specific examples are presented. The discussion of assay methods cites selected assay methods suitable for monitoring enzyme activities in plants using natural, synthetic, dye‐labeled or radiolabeled substrates in different technical combinations. Immunochemical assays of enzymes, characterization of antibodies, and practical examples illustrating how these techniques can be used are also presented.     

A critical review of the specifications and performance of antibody and DNA-based methods for detection and quantification of allergens in foods

Despite the availability of a large number of antibody and DNA based methods for detection and quantification of allergens in food there remain significant difficulties in selecting the optimum technique to employ. Published methods from research groups mostly contain sufficient detail concerning target antigen, calibration procedures and method performance to allow replication by others. However, routine allergen testing by the food industry relies upon commercialised test kits and frequently the suppliers provide disappointingly little specification detail on the grounds that this is proprietary information. In this review we have made a critical assessment of the published literature describing the performance of both commercial and non-commercial test kits for food allergens over the period 2008–2018. Mass spectrometric methods, which have the potential to become reference methods for allergens, are not covered in this review. Available information on the specifications of commercial ELISA and LFD test kits are tabulated for milk, egg and peanut allergens, where possible linking to publications concerning collaborative studies and proficiency testing. For a number of commercial PCR test kits, specifications provided by manufacturers for detection of a small selection of allergen are tabulated. In conclusion we support the views of others of the critical need for allergen reference materials as the way forward to improve the comparability of different testing strategies in foods.     

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.     

Current methods for mycotoxins analysis and innovative strategies for their reduction in cereals: an overview

Mycotoxins are secondary metabolites produced by moulds in food that are considered a substantial issue in the context of food safety, due to their acute and chronic toxic effects on animals and humans. Therefore, new accurate methods for their identification and quantification are constantly developed in order to increase the performance of extraction, improve the accuracy of identification and reduce the limit of detection. At the same time, several industrial practices have shown the ability to reduce the level of mycotoxin contamination in food. In particular, a decrease in the amount of mycotoxins could result from standard processes naturally used for food processing or by procedures strategically introduced during processing, with the specific aim of reducing the amount of mycotoxins. In this review, the current methods adopted for accurate analyses of mycotoxins in cereals (aflatoxins, ochratoxins, trichothecenes, fumonisins) are discussed. In addition, both conventional and innovative strategies adopted to obtain safer finished products from common cereals intended for human consumption will be explored and analysed. © 2018 Society of Chemical Industry     

Identification of Bioactive Peptides from Cereal Storage Proteins and Their Potential Role in Prevention of Chronic Diseases

Cereal grains, such as wheat, barley, rice, rye, oat, millet, sorghum, and corn, have been staples in human diets since ancient times. At present, there is a significant body of scientific evidence showing the health benefits of consuming whole grains in chronic disease prevention, particularly in regards to diabetes, cardiovascular disease, and cancer. The objective was to determine bioactive peptides in cereal grains that may prevent cardiovascular disease, cancer, inflammation, and diabetes. Bioactive peptides that may be obtained from cereal grains, particularly wheat, oat, barley, and rice, were identified. Bioactive peptides that play a role in chronic disease prevention have been found primarily in legumes and dairy products; although research connecting cereal grains with potential bioactive peptide activity is limited. In this review, 4 cereal grains, wheat, oat, barley, and rice, were evaluated for bioactive peptide potential using the BIOPEP database. In addition, research information was compiled for each grain regarding evidence about the effect of their proteins in prevention of chronic diseases. All 4 grains showed high occurrence frequencies of angiotensin‐converting enzyme‐inhibitor peptides (A = 0.239 to 0.511), as well as of dipeptidyl peptidase‐inhibitor and antithrombotic, antioxidant, hypotensive, and opioid activity. Wheat and rice proteins had anticancer sequences present. Wheat and barley showed the greatest diversity and abundance of potential biological activity among the cereal proteins. Further research needs to be conducted to learn how these biologically active peptide sequences are released from cereal grains. This study supports the notion that cereal grains are a nutritious part of a healthy diet by preventing chronic diseases.     

Advances on the molecular characterization,clinical relevance,and detection methods of Gadiform parvalbumin allergens

Gadiform order includes several fish families, from which Gadidae and Merlucciidae are part of, comprising the most commercially important and highly appreciated fish species, such as cod, pollock, haddock, and hake. Parvalbumins, classified as calcium-binding proteins, are considered the main components involved in the majority of fish allergies. Nine and thirteen parvalbumins were identified in different fish species from Gadidae and Merlucciidae families, respectively. This review intends to describe their molecular characterization and the clinical relevance, as well as the prevalence of fish allergy. In addition, the main protein- and DNA-based methods to detect fish allergens are fully reviewed owing to their importance in the safeguard of sensitized/allergic individuals.     

First ring-trial validation of real-time PCR methods for the quantification of allergenic food ingredients

The first interlaboratory validation of two food allergen quantification methods using real-time PCR is described. Methods for the specific detection and quantification of soybean and white mustard in boiled sausages were used. Matrix-based calibrants spiked with defined amounts of soybean and white mustard were applied for quantitative evaluation. The lowest spike level of 10?mg soybean and white mustard per kilogram could reproducibly be detected. Recovery in spiked sausages was between 82 and 99?% for soy and between 80 and 93?% for mustard. Reproducibility standard deviation was in the range that would be acceptable, for example, for quantitative GMO analytical methods (<35?%).     

Validation of real-time PCR methods for the quantification of transgenic contaminations in rape seed

At present genetically modified oilseed rape (Brassica napus) is not allowed to be cultivated in the countries of the European community. This is because rape seed has to be free of any transgenic material if it is destined for growth in the European Community. However, a new regulation is forthcoming that will distinguish seed to be labeled from seed that is not to be labeled by a legal threshold value for the content of transgenic material. In this paper real-time PCR methods are described that are applicable for the quantification of transgenic contaminants after screening and identification analysis. The validation of their quantification is demonstrated for contaminants with resistance to the herbicides Basta and Roundup Ready in samples of conventional rape seed. The limits of quantification were determined for both systems for 50 copies of the transgenic DNA in the reaction assay (confidence interval lower than 30% at a 95% probability level) corresponding to 0.1% of transgenic DNA in the total amount of genomic DNA. Results show that the real-time PCRs established are applicable with the GeneAmp sequence detection system (Applied Biosystems) as well as with the Light Cycler (Roche). The methods described in this paper can be used for the assessment of a contamination in rape seed according to future threshold regulations.     

Proteomics of major bovine milk proteins: Novel insights

Milk proteomics covers the identification, characterisation and quantification of milk proteins. Its applications vary from the basic composition of milk proteins to their post-translational modifications (PTMs), occurring naturally or via processing and storage. Through the combination of liquid chromatography or two-dimensional gel electrophoresis with advanced mass spectrometry, milk proteomics has revealed PTMs that affect milk protein structural and functional properties. This review discusses detection by proteomics-based methods with special emphasis on natural and process induced PTMs in the major bovine milk proteins. The review covers the importance of milk proteomics in determining PTMs, especially those formed by heat treatment and during storage, and highlights some breakthroughs in PTM studies. Furthermore, aspects and applications of quantitative proteomics on milk proteins and bioinformatics are covered.     

Identification of oat (<Emphasis Type="Italic">Avena sativa</Emphasis>) and buckwheat (<Emphasis Type="Italic">Fagopyrum esculentum</Emphasis>) proteins and their prolamin fractions using two-dimensional polyacrylamide gel electrophoresis

Total (non-fractionated) kernel proteins and the prolamin fraction (soluble in 75% ethanol) were extracted from oat (Avena sativa) var. Flämingstern kernel and from buckwheat (Fagopyrum esculentum) var. Kora kernel. As for buckwheat, extraction was effective only after kernel dehulling which allowed the removal of tannins and phenolic compounds that form complexes with proteins during extraction. The extracted proteins were analyzed using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Gels of the prolamin fractions of oat and buckwheat were used as reference gels in order to detect prolamins on gels of total kernel proteins. The occurrence of 26 and 29 spots corresponding to prolamins was found on gels of total oat proteins and on gels of total buckwheat proteins, respectively. The electrophoretic images of oat and buckwheat prolamins revealed organized subregions containing spots with similar isoelectric points (pI) and various molecular weights (MW), mostly on oat prolamin gels and spots of similar molecular weights with various isoelectric points, mostly on buckwheat prolamin gels. Such organized subregions can be used as identifiers for the occurrence of prolamin fractions in total proteins (particularly as regards buckwheat proteins).