Application of isotherm calorimetry in the development of foods containing probiotic live flora and enriched with bioavailable Ca<Superscript>2+</Superscript>

The development of functional foods of probiotic effect based on the slime-producing strains isolated in the 1980s, and that of enriched with Ca on the utilization of the high Ca-containing whey of the quarg production in the Carpathian basin using fermentation. The probiotic properties of the slime-producing microbe strains isolated have been proved by in vitro and in vivo examinations. We have used an isotherm DSC method to identify the probiotic microbes. The percentile ratio of probiotic and other microbes was determined in the product by this technique. By utilization of quarg whey a special additive food for Ca-enrichment has been developed which is suitable to complete or enrich different foods (dairy, meat and bakery products). The products developed are: probiotic kefir (Synbiofir), probiotic sour cream, probiotic butter cream, poultry meat products completed with Ca, bakery products completed with Ca.     

Reversed-phase high-performance liquid chromatography–electrospray mass spectrometry profiling of transgenic and non-transgenic maize for cultivar characterization

A reversed-phase high-performance liquid chromatography–electrospray mass spectrometry (RP-HPLC–ESI-MS (ion trap)) method is developed, for the first time, for profiling transgenic and non-transgenic maize with the aim of cultivar characterization. To optimize chromatographic conditions the following parameters were studied: column, gradient, and ion-pairing reagent. Moreover, the influence in the MS signal of the variation of the capillary voltage and the accumulated ions in the trap was also studied. The developed method was applied to the profiling of different protein fractions (albumin, globulin, prolamin, and glutelin) isolated from Bt transgenic and non-transgenic maize cultivars. Moreover, different maize samples, namely, maize cultivars from different geographical origins (USA, Canada, France, and Spain), transgenic maize samples with certified GMO content, and three transgenic Bt maize cultivars with their isogenic non-transgenic counterparts (Aristis Bt vs. Aristis, PR33P67 vs. PR33P66, and DKC6575 vs. Tietar) were profiled by the developed method. Mass spectra obtained for certain peaks in the maize cultivars studied resulted, in some occasions, useful for cultivar characterization and differentiation. The comparison of UV and MS profiles and mass spectra corresponding to the protein fractions with those of the whole seeds enabled the assignment of some peaks.     

Automated flow system on-line to LC with postcolumn derivatisation for determination of sugars in carbohydrate-rich foods

Summary A method for the direct determination of carbohydrates in foods using an automated-flow system coupled on-line to a high-performance liquid chromatograph is proposed. The method is based on postcolumn derivatisation of reducing sugars with p-aminobenzoic acid hydrazide in an alkaline medium following elution from the chromatographic column with an acetonitrile: water gradient as mobile phase. The manifold allows non-reducing sugars to be hydrolysed prior to insertion into the chromatograph, thus making them compatible with the derivatisation reaction and with continuous decolorisation of the sample on an activated carbon column. The method allows determination of six sugars in contents between 0.005 and 4% (w/v) with high precision (3.8–5.0%RSD). For analytical validation, it was applied to determination of fructose, sucrose, maltose, lactose and maltotriose in two reference materials (milk powder and sugar). Finally, the method was used to determine sugars in a variety of carbohydrate-rich foods.     

拮抗作用及传统医学的食物相克

微量元素的生理活性取决于其化合物的溶解性,配位状态、浓度、溶液酸度以及其它元素浓度,拮抗作用的本质是元素的结构－性质－活性关系。其机理主要包括直接反应、形成ＭＴ的抑制反应,相似元素竞争配位部位以及社会、心理、遗传和个体易感性等,传统医学煌食物相克的实质还是物质的拮抗作用。     

高效液相色谱-串联质谱法测定食品中曲酸

建立了食品中新型防腐剂曲酸的高效液相色谱-串联质谱的定量测定方法。动物禽肉、鱼虾甲壳类、酱菜类、水果蔬菜、面制品等固体样品经乙腈提取;酱及酱油、醋、酒、饮料、糖浆等液体样品经水稀释,乙酸锌和亚铁氰化钾沉淀蛋白;以C18柱为分离柱,流动相为乙腈和5 mmol/L乙酸铵甲酸溶液,采用电喷雾串联四极杆质谱进行检测。选择1个母离子和2个子离子进行选择反应监测,以13C6-曲酸作为内标,选择信号最强的子离子进行定量测定。固体类基质中的定量限(按信噪比(S/N)大于10计)为0.1 mg/kg;液体类基质中的定量限为2.5 mg/kg。在0.1～2.0 mg/L范围内呈现良好的线性关系,相关系数r＞0.99。各种基质在3个添加水平的平均回收率在72.6%～114%之间,相对标准偏差均小于11.4%。本方法简单实用,准确可靠,适用范围包括了食品中可能使用曲酸这种食品添加剂的大部分基质,可以满足进出口食品中曲酸的定性和定量要求。     

高效液相色谱-串联质谱法测定动物源食品中3-甲基喹喔啉-2-羧酸和喹喔啉-2-羧酸残留

建立了动物源食品中喹喔啉类药物代谢残留标识物3-甲基喹喔啉-2-羧酸和喹喔啉-2-羧酸的高效液相色谱-串联质谱检测方法。样品在酸性环境水解,经乙酸乙酯、磷酸盐缓冲液依次提取,Oasis MAX固相萃取小柱净化,用Waters Xterra MS C18柱(150 mm×2.1 mm, 5 μm)分离,以甲醇-0.2%甲酸为流动相梯度洗脱,采用多反应监测(MRM)正离子模式检测,内标法定量。各物质在1.0～20.0 μg/L范围内线性关系良好,相关系数均不低于0.9996; 3-甲基喹喔啉-2-羧酸和喹喔啉-2-羧酸在0.1、0.2、1.0 μg/kg加标水平的回收率为62.4%～118%,相对标准偏差为1.48%～28.1%;定量限(以信噪比≥10计)为0.1 μg/kg。该方法简单、灵敏、稳定,可满足猪肉、猪肝、鸡肉、鸡肝、鱼、虾等动物源食品中3-甲基喹喔啉-2-羧酸和喹喔啉-2-羧酸残留的检测与确证需要。     

食品、药品安全检测技术与仪器

食品、药品安全是世人最关注的问题之一。讨论了食品药品安全的检测方法和仪器,同时,对有关问题进行了讨论。     

A sensitive method for quantification of the insecticide spinetoram in 13 different plant- and animal-type foods by ultra-high performance liquid chromatography-tandem mass spectrometry

We developed a simple, sensitive and rapid analytical method for simultaneous quantification of spinetoram (XDE-175-L and XDE-175-J) residue in foods originating from plants (cucumber, cabbage, eggplant, pepper, bayberry, mango, rice, wheat, and codonopsis) or animals (eggs, milk, pork, and chicken). The method was validated by ultra-high performance liquid chromatography coupled to tandem mass spectrometry, run in the positive-ion mode with selected reaction monitoring. Briefly, the samples were extracted with acetonitrile and purified via dispersive solid-phase extraction with octadecylsilane, primary secondary amine, or graphitized carbon black, used either singly or in combination. The method provides good linearity (R² ≥ 0.9956) and outstanding performance (trueness and recovery percentages 80.1–111.3%; intra-day/inter-day precision of 1.2–9.7% and 3.9–12.9%). For all food matrices, the limit of quantification was 0.125 µg kg^–1 for XDE-175-L and 0.375 µg kg^–1 for XDE-175-J. We also validated the applicability of the method using 130 samples obtained from commercial sources, which revealed trace amounts of spinetoram in 28 of those samples. The data indicated that the method yields reproducible results and is sufficiently sensitive for the detecting trace amounts of spinetoram in plant- and animal-type foods.     

正相高效液相色谱法测定食物中8种维生素E异构体及维生素A

建立了正相高效液相色谱测定食物中8种维生素E异构体及维生素A的方法。样品中的维生素E异构体和维生素A经皂化和液液萃取,Waters ACQUITY^TM UPLC BEH Amide色谱柱(150 mm×3.0 mm, 1.7 μm)分离,体积比为90 : 10的正己烷与叔丁基甲基醚-四氢呋喃-甲醇(20:10:1, v/v/v)为流动相,荧光检测器和紫外检测器串联检测。4种生育酚在5.0~60.0 mg/L(r²≥0.9999)、维生素A和4种三烯生育酚在0.5~6.0 mg/L(r²≥0.9996)范围内具有良好的线性,各基质中目标物的检出限在20~60 μg/kg之间;9个组分在各基质中的加标回收率为79.2%~114.2%,相对标准偏差(RSD)为1%~12%。该方法简便、灵敏、可靠、环保,可用于食物中8种维生素E异构体以及维生素A含量的同时测定。     

高效液相色谱-串联质谱法测定焙烤食品及其塑料包装中31种邻苯二甲酸酯

建立了高效液相色谱-三重四极杆串联质谱（HPLC-MS/MS）测定焙烤食品及其塑料包装中31种邻苯二甲酸酯（PAEs）的方法。焙烤食品采用乙酸乙酯超声提取,提取液经冷冻（-18℃）、低温高速离心净化,剪碎后的塑料包装材料采用体积比为1：1：1的甲醇-丙酮-正己烷混合溶剂进行液液超声萃取后进入HPLC-MS/MS分析。采用MGⅢC₁₈色谱柱（2.0 mm×100 mm,5 μm）,选择反应监测（SRM）模式测定。实验结果表明,31种邻苯二甲酸酯的特征离子质量色谱峰的峰面积与其质量浓度在各自的质量浓度范围内线性关系良好（r²≥0.9958）。样品加标回收率除邻苯二甲酸二月桂酯（DLP）为70.9%～109.7%外,其余30种化合物为80.1%～113.0%,相对标准偏差（n=6）为1.0%～13.7%。31种PAEs的检出限在0.02～8.15 μg/kg之间,定量限在0.07～27.17 μg/kg之间。应用该方法检测了面包、饼干、糕点、馅料4大类焙烤食品及其塑料包装中31种邻苯二甲酸酯的含量。该方法具有操作简单、快速、准确度和精密度高等优点,满足日常检测的要求。