The determination of trypsin inhibitor levels in foodstuffs

The trypsin inhibitor activity of processed foods can be determined by measuring the loss of activity of added trypsin under standard conditions. Observed values are not usually independent of the degree of inhibition, and averaging over a range of inhibition levels or extrapolation to zero inhibition may not produce a more reliable value. A somewhat modified method is described which has been tested in two laboratories and used for large numbers of different samples on a routine basis; its application and limitations are discussed.     

食品中甜味剂的检测方法

文章引用文献一百多篇,比较详细地对近年来食品中甜味剂检测中应用的各种技术方法进行了总结。     

食品中黄曲霉毒素检测方法研究进展

黄曲霉毒素是自然界中黄曲霉菌和寄生曲霉菌分泌的一种次级代谢产物,容易污染粮食作物及其制品,主要存在于霉变的花生、大米、玉米等作物及与其相关食品中。黄曲霉毒素具有极强的毒性和致癌性,是目前已发现的最强的天然致癌物质,严重威胁人类健康。近年来黄曲霉毒素已成为食品安全领域的重点关注对象。本文着重从黄曲霉毒素的前处理方法和检测方法两方面介绍国内外目前食品中常用的黄曲霉毒素检测手段,包括传统的经典检测方法和快速检测方法,并对其进行比较和评价,同时对粮油食品中的黄曲霉毒素检测方法的发展方向进行展望,以供国内外同行参考借鉴。     

The determination of protein in biological materials and foodstuffs

Summary. Three methods for determining protein, the Folin, dye-binding and nitration procedures, have been investigated, modified when necessary, and applied to mycelial systems, flour and dried egg. All three methods give different results with different protein standards, indicating that the values obtained from different samples can only be relative rather than absolute.     

食品中全氟化合物分析技术研究进展

全氟化合物(perfluorinated compounds,PFCs)是一类人工合成的脂肪烃类化合物,自上个世纪50年代合成以来,该类化合物以其优良的稳定性及表面活性作为加工助剂被应用于多种民用及工业领域,如纺织品、灭火器和油漆等行业。近些年来越来越多的调查研究发现,在空气、沉积物、饮用水、海水和食品中检测出全氟类化合物。膳食作为人体暴露PFCs的重要途径之一,已受到了各国研究人员的重视。本文综述了食品中PFCs的检测技术的研究进展,讨论了不同食品中PFCs的前处理及检测方法,当前主要采用离子对液液萃取和液固萃取,WAX柱净化提取液,液相色谱-质谱联用技术定量分析食品中的PFCs。由于食品中PFCs处于痕量水平,对该类物质的检测方法中空白本底的控制尤为重要。另外,全氟化合物存在的多种同分异构体之间的差异将是研究人员对其准确监测的困难之一。     

Automated determination of vitamin C in some fortified foodstuffs

An automated method for the determination of ascorbic acid has been applied to a variety of vitamin fortified food products. The method is based on the reduction of 2,6-dichloroindophenol by ascorbic acid and shows a detection limit of 0.006 mg/ml with a linear absorbance relationship to 0.200 mg/ml. The method was applied to vitamin fortified cereal products, soya protein snacks and beverage concentrates over a broad range of vitamin levels. The results compared favourably with potentiometric titration for the majority of products studied. It has been shown that the automated procedure is the method of choice for the determination of ascorbic acid in the large number of food products studied.     

高效液相色谱法测定食品中的黄曲霉毒素B1

用甲醇-水(55:45)、三氯甲烷、苯-乙腈(98:2)等有机溶剂作为提取剂,用三氟乙酸作衍生剂,通过带荧光检测器的高效液相色谱仪测定食品中黄曲霉毒素B1的含量。结果表明,该方法的线性回归关系良好,方程为y=3.10x-0.63,相关系数r=0.9999。不同样品中黄曲霉毒素B1回收率为84.2%-86.9%,平均变异系数RSD=6.09%。在总共150份检测的玉米、大米和花生样品中,黄曲霉毒素B1总的检出率为82.0%,总的超标率仅为6%,但不同样品中黄曲霉毒素B1含量的变幅较大(0-485.34μg/kg)。     

食品中新出现成分过敏原性评估及阈值的确定

食物中能使机体产生过敏反应抗原分子称为食物过敏原,可引发少数人产生过强烈的过敏反应,危及生命。本文通过介绍国际生命科学研究所及澳洲新西兰食品标准管理局如何评估对民众的健康产生影响的新过敏原,评价基因改良食物过敏性的树状评价模式,引起消费者对食品中新出现的过敏原引起足够的了解及关注。另外通过介绍过敏原阈值的定义,对过敏原风险评估较有意义的确定方法——概率模型及影响阈值确定的因素,提醒消费者食物过敏的潜在危险性,跟进各国专业人员评估及阈值的最新研究进展,增强食品安全意识,共同推进食品过敏原研究及管理工作的顺利实施。     

The determination of pyridoxine in enriched foodstuffs by direct spectrofluorometric measurement

A new method for the assay of added pyridoxine in foods is proposed which is simple and rapid. The method utilises the natural fluorescence of pyridoxine and a blank value is obtained by the addition of an excess of borate which quenches the fluorescence of pyridoxine. Experimental values obtained are compared with microbiological determinations. The interference of pyridoxal and pyridoxamine is less than 5% for each when they are present in equimolar amounts to pyridoxine. The practical working range for the method is 0.1–20 μg pyri-doxine/ml.     

Enzymatic extraction procedure for the liquid chromatographic determination of niacin in foodstuffs

An enzymatic extraction procedure for the determination of the niacin present in foodstuffs by means of a NAD glycohydrolase (or NADase) has been proposed as a replacement for the hydrochloric acid hydrolysis usually used. The determination of nicotinic acid and nicotinamide by HPLC/fluorimetry [according to Lahély et al. (Food Chemistry, 1999, 65, 129)] has made it possible to show that the acid treatment very definitely led to the release of forms of nicotinic acid not bioavailable in some foodstuffs (wheat flour, wheat germ, peanuts), unlike hydrolysis with NADase from Neurospora crassa [37 °C, 18 h, pH 4.5, 24 μg g⁻¹ of sample (0.013 U g⁻¹)] which led to both an accurate determination of the respective contents of nicotinic acid and nicotinamide and a reliable estimation of the bioavailable niacin in the different foodstuffs analysed. The combined addition of a protease and an amylase to the NADase, sometimes recommended when acid hydrolysis was used, proved to be superfluous.     

Rapid determination of free anthocyanins in foodstuffs using high performance liquid chromatography

Anthocyanins constitute a major group of natural pigments, and they are responsible for the colours of fruits and vegetables. A rapid and feasible assay procedure for the determination of free forms of the six most abundant anthocyanins in foods is described. The 3-glucoside forms of pelargonidin, cyanidin, peonidin, delphinidin, petunidin and malvidin with the aglycone cyanidin (as internal standard) were separated by gradient elution and quantified using HPLC-DAD within 18 min. A fast sample preparation step was employed which allows direct injection of samples to the chromatograph without need of chemical extraction. Testing on 28 different vegetable, fruit and processed commercial product samples demonstrated applicability in the concentration range of about 80–420 ng/mL with an accuracy of 99.2 ± 0.2% and an average precision of 0.8%. The method was suggested as a cheap and robust alternative to the previous ones that employ multi-step sample treatment protocols.     

Improved methodology for the electrophoretic determination of horse meat in heated foodstuffs

Using linear gradient polyacrylamide gel electrophoresis to separate constituent proteins, horse meat could be clearly distinguished from beef even after heating for 20 min at up to 120°C.     

食品及其包装材料中双酚A的检测研究进展

双酚A(BPA)是世界上使用最广泛的一类有机化工原料之一,人们几乎每天都在接触和使用该化合物及其制品。由于其具有类雌激素特性,引起人们对其影响身体健康可能性的关注,特别是食品及食品包装材料中双酚A的危害成为争论的焦点。本文综述了双酚A的残留现状,以及食品及其包装材料中双酚A检测方法的研究进展,着重介绍了液相色谱法、气相色谱法、免疫分析法、光谱分析法、电化学分析法、传感器法等检测方法的应用情况,并对检测方法的发展进行了展望。      

对粮油食品中黄曲霉毒素B1测定方法的探讨

本文对国标规定的薄层荧光法和自选的EAB1—95型黄曲霉毒素测定仪法检验粮油食品中黄曲霉毒素B1的操作方法及其结果进行了探讨,从而得出后者比前者操作简便、省时、省力。     

液相色谱－串联质谱法同时测定保健食品中 四种违禁药物含量

建立了超高效液相色谱-串联质谱法测定保健食品中西地那非、他达那非、伐地那非以及红地那非四种违禁药物含量的方法。采用ACQUITY UPLC BEH C18（100 mm×2.1 mm,1.7μm）色谱柱,以甲醇和添加0.1%甲酸5 mmol乙酸铵为流动相,梯度洗脱程序,进样分析20 min,在电喷雾正离子模式下以多反应监测(MRM)方式检测,外标法定量。四种那非类违禁药物的检出限(LOD,S/N=3)和定量限(LOD,S/N=10)分别0.1～0.5 μg/kg和0.3～2.0 μg/kg在0.1～100 μg/kg浓度范围内线性关系良好(r>0.99),加标回收率为73.6%～90.4%,相对标准偏差为1.0～7.9。     

Sample preparation for photometric determination of histamine in foodstuffs compared with capillary electrophoresis

 To determine levels of histamine, two methods were used, photometry in conjunction with two sample clean-up procedures, and capillary zone electrophoresis (CZE). The two sample clean-up procedures used were liquid liquid extraction (LLE) with n-butanol and solid phase extraction (SPE). Using CZE, the separation of histamine from the matrix was good. The other method, photometry, represents a classic and simple method, that can be employed for in situ measurement of histamine. We found that it was necessary to clean up the samples prior to photometry; if this was not done, the recorded levels of histamine were higher than those determined by CZE. In order to determine levels of histamine, both of these rapid tests were applied to ten different foodstuffs. The levels of histamine measured using photometry following either LLE or SPE were compared. The results indicated that photometry is a suitable method for the measurement of histamine, although the sample solutions have to be purified by either LLE or SPE. Samples do not need to be cleaned up before CZE because there is no interference between histamine and attendant material. Both sample clean-up procedures were applied to the following foodstuffs: tomatoes, sauerkraut, tuna, leaf spinach, cream spinach, white wine and mackerel. The differences of the measured values vary between 3% and 18% for LLE and 6% and 27% for SPE. For the other foodstuffs, such as beef, beer and non-alcoholic beer, only one sample clean-up procedure is suitable. LLE used for beef and beer leads to differences in measured levels of histamine between 18% and 50%, respectively, whereas SPE used for non-alcoholic beer leads to differences of 20%. Received: 3 September 1997 / Revised version: 23 October 1997     

Synthesis of an ionic N-nitrosamine and a method for its determination in foodstuffs

Summary A model ionic N-nitrosamine (N-nitroso-N¹N¹-dimethylpiperazinium iodide) was synthesised in order to develop an appropriate analytical method for examining the possible incidence of this class of compounds in food. A procedure suitable for its analysis in biological samples is described and is based on preparation of an aqueous extract, ion-pair extraction into an organic solvent, separation by high-performance liquid chromatography and detection with a thermal-energy analyzer. The average recovery of the ionic N-nitrosamine from cured meat was 83% at 200 g/kg; the detection limit was 50 gm/kg. bei den Muskelproben nahezu 30% der mit Hilfe der

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Synthese eines Ionischen N-Nitrosamins und eine Methode für dessen Analyse in Lebensmitteln

Zusammenfassung Ein Modell eines ionischen N-Nitrosamins (N-Nitroso-N¹N¹-dimethylpiperaziniodid) wurde synthetisiert, um die entsprechende analytische Methode zur Prüfung des möglichen Auftretens von Verbindungen dieser Klasse in Lebensmitteln zu entwickeln. Es wird ein für die Analyse dieses Stoffes in biologischen Proben geeignetes Verfahren beschrieben, das auf der Zubereitung eines wäßrigen Extrakts, Ionenpaar-Extraktion in einem organischen Lösungsmittel, Trennung durch Hochleistungs-Flüssigkeitschromatographie und Nachweis mit Hilfe eines thermischen Energieanalysators beruht. Aus geräuchertem Fleisch mit einem Gehalt von 200 g ionischem N-Nitrosamin/kg wurden im Durchschnitt 83% des Stoffes extrahiert, die Methode hat eine Nachweisgrenze von 50 g/kg.

     

Sample preparation for photometric determination of histamine in foodstuffs compared with capillary electrophoresis

 To determine levels of histamine, two methods were used, photometry in conjunction with two sample clean-up procedures, and capillary zone electrophoresis (CZE). The two sample clean-up procedures used were liquid liquid extraction (LLE) with n-butanol and solid phase extraction (SPE). Using CZE, the separation of histamine from the matrix was good. The other method, photometry, represents a classic and simple method, that can be employed for in situ measurement of histamine. We found that it was necessary to clean up the samples prior to photometry; if this was not done, the recorded levels of histamine were higher than those determined by CZE. In order to determine levels of histamine, both of these rapid tests were applied to ten different foodstuffs. The levels of histamine measured using photometry following either LLE or SPE were compared. The results indicated that photometry is a suitable method for the measurement of histamine, although the sample solutions have to be purified by either LLE or SPE. Samples do not need to be cleaned up before CZE because there is no interference between histamine and attendant material. Both sample clean-up procedures were applied to the following foodstuffs: tomatoes, sauerkraut, tuna, leaf spinach, cream spinach, white wine and mackerel. The differences of the measured values vary between 3% and 18% for LLE and 6% and 27% for SPE. For the other foodstuffs, such as beef, beer and non-alcoholic beer, only one sample clean-up procedure is suitable. LLE used for beef and beer leads to differences in measured levels of histamine between 18% and 50%, respectively, whereas SPE used for non-alcoholic beer leads to differences of 20%. Received: 3 September 1997 / Revised version: 23 October 1997     

Radioisotopic method for the determination of low and very low proteolytic activities in foodstuffs

Zusammenfassung Das Verfahren zum Nachweis der proteolytischen Aktivitat unter Verwendung von mit¹²⁵I-markiertem menschlichen Serumalbumin als Substrat wurde auf die Bestimmung der proteolytischen Aktivität in Lebensmitteln angewendet. Die Methode ist sehr empfindlich and ermöglicht auch die Bestimmung sehr niedriger proteolytischer Aktivitäten in allen Lebensmittel. Es wird die Optimierung der Methode zur Bestimmung der proteolytischen Aktivitäten in Fleisch und Fleischprodukten beschrieben, Bowie die Bestimmung der proteolytischen Aktivitat in Milchprodukten und Getreideprodukten.

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Radioisotopic method for the determination of low and very low proteolytic activities in foodstuffs

Summary A proteolytic activity assay using denatured¹²⁵I-labelled human serum albumin as substrate was applied to the determination of proteolytic activity of foodstuffs. The method is very sensitive and enables the determination of very low activities in all kinds of foodstuffs. The optimization of the method for the determination of proteolytic activities in meat and meat products is described. The determination of activities in milk products and cereals is also presented.