An international quality assurance scheme for the quantitation of daidzein and genistein in food,urine and plasma

This quality assurance (proficiency testing) scheme was commissioned to enable the Food Standards Agency (FSA) to determine the quality of analytical results submitted by researchers measuring the concentrations of phytoestrogens in foods and biological fluids in FSA-funded research projects, and also, to demonstrate that FSA-funded laboratories are producing consistent and precise results. Non-FSA-funded laboratories from around the world were also invited to join in the scheme to increase the number participants. A secondary objective was to highlight the most successful methodologies used to analyse phytoestrogens.     

Postharvest dehydration of wine white grapes to increase genistein, daidzein and the main carotenoids

Wine white grape bunches of the Grechetto variety were dehydrated at 10, 20 and 30°C, RH 45% and forced air ventilation of 1.5m/s. Chemical and metabolic changes due to the effect of dehydration were studied at various stages of weight loss: 10%, 20%, 30% and 40%. Berry colour at 10 and 20°C tended to become greener with dehydration but at 30°C, at the final sampling, the colour darkened. Acidity decreased in all samples, while sugars increased. Total phenol content increased at 10°C until 30% weight loss was reached and then declined, while at 20 and 30°C the concentration decreased immediately. The contents of lutein and β-carotene (respectively 68 and 58mg/kg d.w.), representing the 80% of total carotenoids, did not change significantly until the 30% of weight loss, when at 30°C the value increased above all for lutein while at 10 and 20°C, the contents decreased significantly. Daidzein, at 10°C, rose significantly from about 150μg/kg d.w. to 1434μg/kg d.w. at 20% weight loss and then declined; at the same weight loss percentage, the genistein concentration began to increase. At 20°C both isoflavones rose until the end of the experiment, reaching values similar to the sample at 10°C. A temperature of 30°C was deleterious to grape isoflavones. A discussion on the changes in isoflavones related to temperature and time is reported.     

A survey of pork quality in relation to pre-slaughter conditions, slaughterhouse facilities, and quality assurance

A survey at five pigs' slaughterhouses was performed to investigate the effect of a quality assurance system, pre-slaughter conditions and slaughterhouse facilities on pork quality. Totally, 2246 pigs were included over four transports per slaughterhouse, i.e. two transports were produced according to a quality assurance system and the other two were conventional pigs. Meat quality was measured on 446 pigs. The pH in the longissimus dorsi muscle and the electrical conductivity in the semimembranosus muscle were measured 30min post-mortem. Twenty-four hours later pH and electrical conductivity in both the longissimus dorsi and the semimembranosus muscle were measured. Pigs managed according to a chain quality protocol showed an overall higher potential for improved meat quality. Differences in meat quality between the different slaughterhouses were also found, however they were dependent on muscle type and time of measuring. Influencing factors on pork quality seemed to be stocking density during transport, the handling during offloading the pigs from the truck, stocking density, and air temperature during lairage.     

婴幼儿配方食品中维生素D标准检验方法等效性评价研究

目的 评价研究婴幼儿配方食品中维生素D标准检验方法等效性.方法 采用成对方法比较,通过实验室间比对研究,结合方法性能评价与运用合适统计工具对标准检验方法的分析结果进行定性定量评价.结果 综合对方法性能与检测结果的评价,成对方法之间无显著性差异,在等效边界15％时方法等效,检测均值的差异均低于可接受临界差异.结论 3对成...     

特殊医学用途配方食品和婴幼儿配方乳粉中氟含量测定方法的改进

目的对国标方法测定特殊医学用途配方食品和婴幼儿配方乳粉类产品中氟含量测定进行改进。方法样品经Taka淀粉酶酶解,高氯酸溶液沉淀蛋白质,加入总离子强度缓冲剂消除金属干扰离子,过滤后,使用氟离子选择电极测定样品中氟含量。结果与国标法相比,改进方法使测试溶液澄清,电极响应更快,回收率范围为92.8%～107.5%,相对标准偏差为3.36%～4.38%,能满足方法准确度和精密度要求。结论改进后的方法能够满足方法学要求,能够准确地检测特殊医学用途配方食品和婴幼儿配方乳粉类产品中的氟含量。     

婴幼儿配方乳粉中三聚氰胺检测中前处理方法的优化

目的改进婴幼儿配方乳粉中三聚氰胺的检测方法。方法样品经高浓度三氯乙酸溶液-乙腈提取过滤,后经阳离子交换固相萃取柱净化,用高效液相色谱法测定,采用外标法定量。结果改进方法的检测时间缩短4 h,在0.5~10μg/m L范围内检测结果线性关系良好,方法检出限为0.5 mg/kg,定量限为1.5 mg/kg,回收率提高到99.3%~102%,精密度为0.47%,稳定性相对标准偏差为0.96%,能力验证结果表明可靠性好。结论改进方法能快速有效对婴幼儿配方乳粉产品进行检测,结果可靠,具有实践应用价值。     

婴儿配方粉中溶菌酶活力的测定及其校正系数的研究

在婴儿配方粉中添加溶菌酶已成为高档婴儿粉的一种趋势，因此奶粉中溶菌酶活力成为判定其质量的重要指标。根据经典的分光光度法探索出测定奶粉中溶菌活力的方法，并以纯酶液人对照初步得出校正系数r=1.2；本试验测得市售婴儿粉中每克粉中溶菌酶活力为25960u。     

婴儿配方乳粉中维生素B1、B2含量测定能力验证

目的设计组织婴儿配方乳粉中维生素B_1、维生素B_2含量测定能力验证项目,评价实验室检测婴儿配方乳粉中维生素B_1、维生素B_2的技术能力和水平。方法考核样品中的维生素B_1、维生素B_2在P0.05显著水平时是否均匀,且在整个计划周期内稳定,满足能力验证的要求。通过实施能力验证计划,对来自27个省(自治区)、直辖市的33家实验室的测定结果与指定值比对得到相对偏差,评价实验室检测能力。结果在参加实验室中,维生素B_1总体满意率为90.6%;维生素B_2总体满意率为84.8%。结论多数参加实验室检测能力结果满意,表明乳粉中维生素B_1、维生素B_2检测水平总体良好。对于离群结果进行技术分析,可以帮助实验室查找原因并进行整改。     

婴幼儿配方乳粉中低聚半乳糖含量检测方法的前处理优化

目的优化国际通用的测定婴幼儿奶粉中GOS方法的前处理步骤,提高检测结果的准确度。方法针对前处理条件增加了超声10min的操作步骤;在样液沉降蛋白时,进行离心,确定了最佳的离心条件:10000 r/min, 10 min。此外优化了梯度洗脱时淋洗液比例。经离子色谱检测,外标法定量发现GOS有5个不同特征峰,经验证确定以GOS2作为GOS定量峰,计算GOS含量。结果 GOS质量浓度在5～100μg/mL范围内标准曲线的相关系数(r~2)均大于0.995,在质量分数为0.6、1.2、2.0、3.0、4.0 g/kg 5个加标水平下,方法回收率为100%～120%,相对标准偏差为0.22%～6.40%(n=2)。结论该优化后的方法,样品提取更加充分,样品峰分离效果更好,回收率与重复性良好,结果准确性更高,对准确检测婴幼儿配方乳粉中GOS的含量具有一定的意义。     

乳铁蛋白的功能特性及其在婴儿配方奶粉中的应用

介绍了母乳中乳铁蛋白的功能特性，及其应用在婴儿配方奶粉中对非母乳喂养婴儿营养的重要性，国外有关乳铁蛋白在婴幼儿配方奶粉中的应用情况。探讨了乳铁蛋白在婴儿配方奶粉中应用的研究过程，包括有关配方设计依据、使用的原料、生产工艺流程、检验方法、检验结果等。     

高效液相色谱法测定婴幼儿食品和乳品中泛酸的不确定度分析

目的 评定高效液相色谱法测定婴幼儿配方乳粉中泛酸含量的测量不确定度。方法 依据JJF1059.1-2012《测量不确定度评定与表示》和CNAS-GL06-2018《化学分析中不确定度的评估指南》, 考察测定过程引入不确定度的主要因素, 建立不确定度的数学模型, 并对不确定度的各分量进行计算和合成。 结果 当婴幼儿配方乳粉中泛酸含量为939 μg/100 g, 在95%的置信区间下, 扩展不确定度为30.80 μg/ 100 g (k=2)。评定结果表明, 实验过程的不确定度主要来源为标准物质和曲线拟合。结论 该方法准确可靠, 适用于高效液相色谱法测定婴幼儿配方乳粉中泛酸的不确定度评定, 对检测结果准确度的提高具有指导意义。     

液相色谱-串联质谱法测定婴儿奶粉中三聚氰胺残留量的不确定度评估

目的对液相色谱-串联质谱法测定婴儿奶粉中的三聚氰胺的不确定度进行评估。方法以GB/T22388-2008《原料乳与乳制品中三聚氰胺检测方法》为基础改良方法,测定婴儿奶粉中的三聚氰胺。依据CNAS-GL06:2006《化学分析中不确定度的评估指南》,通过数学建模建立不确定度来源鱼骨图,分析不确定度来源并计算不确定度分量。结果当奶粉中的三聚氰胺残留量为50μg/kg时,测量不确定度为3.70μg/kg(k=2),其中液质仪器校准、重现性和偏差对不确定度影响最大。结论内标法的线性拟合对测量不确定度贡献较小,对三聚氰胺的常规检测具有重要意义。     

婴幼儿配方乳粉的生产质量回顾性分析

目的 对婴幼儿配方乳粉进行回顾性分析, 以评价一定周期内产品的生产和质量稳定性。方法 选择9款婴幼儿配方乳粉产品, 随机抽取一定批次量(n范围: 25~49)的产品, 对3年周期内产品的生产工艺、生产环境、检验和产品数据进行回顾性分析。结果 生产期间环境平均温度在19.2~22.3 ℃, 平均相对湿度在48.9%~55.6%, 产品得率在99.19%~100.03%, 耗损在-0.03%~0.81%。产品中能量的相对标准偏差(relative standard deviation, RSD)在0.43%~0.73%, 宏量营养素RSD在1.10%~4.81%, 总脂肪酸和必须脂肪酸的RSD在2.57%~8.76%, 矿物质类指标比维生素类指标具有范围更窄的RSD。而且, 绝大部分指标检测能力的验证结果满意, 约占总数量的91.21%; 个别指标检测能力验证结果为可疑和不满意, 分别约占总数量的4.95%和3.85%。结论 3年来婴幼儿配方乳粉产品生产质量稳定性好。     

Isolation and molecular identification of Cronobacter spp. from powdered infant formula (PIF) in Bangladesh

Cronobacter spp. formerly known as Enterobacter sakazakii is an occasional contaminant of powdered infant formula (PIF). This pathogen has been associated with out-breaks of a rare form of infant meningitis, necrotizing enterocolitis (NEC), bacteremia and neonate deaths. The organism is ranked by the International Commission for Microbiological Specifications for Foods (ICMSF) as a ‘Severe hazard for restricted populations, life threatening or substantial chronic sequelae or long duration’. Present study aimed to isolate Cronobacter spp. from PIF and clinical samples, such as blood, stool and CSF collected from 93 neonates and child patients, age ranged from 0 to 24 months. We did not detect Cronobacter spp. in any of these samples. Later 32 PIF samples collected from retail markets in Bangladesh were tested for the presence of Cronobacter spp. Of these only one was found to be contaminated with Cronobacter sp. This is the first case of Cronobacter contaminated PIF found in Bangladesh to be reported. The organism was successfully identified based on its typical culture characteristics, producing blue-green colonies on chromogenic DFI agar and also by a standardized conventional PCR assay targeting the alpha glucosidase and 16 S rRNA gene sequence of Cronobacter sp. The 16 S rRNA gene was partially sequenced to provide for the phylogenetic analysis of this isolate (DA01) and found to cluster with some other Cronobacter isolates in the phylogram.     

Microwave-assisted extraction and determination of dicyandiamide residue in infant formula samples by liquid chromatography-tandem mass spectrometry

A simple, precise, accurate, and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of dicyandiamide residue in infant formula samples. Following microwave-assisted extraction with 5% formic acid and clean-up on a Sep-Pak AC-2 SPE cartridge, samples were separated on a ZIC-HILIC HPLC column (150 × 2.1 mm i.d., 5-µm film thickness; Merck KGaA, Darmstadt, Germany) with 20 mM ammonium acetate solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. A linear calibration curve was obtained in the concentration range from 1.0 to 50 ng/mL. Infant formula samples were fortified with dicyandiamide at 3 levels, producing average recovery yields of 83.6 to 95.7%. The limits of detection and quantification of dicyandiamide were 3 and 10 μg/kg, respectively. Due to its simplicity and accuracy, the straightforward method is particularly suitable for routine dicyandiamide detection.     

气相色谱法快速测定婴幼儿配方奶粉中肌醇含量

在GB 5009.270—2016第二法的基础上进行方法改进,建立了能更便捷高效检测婴幼儿配方奶粉中肌醇含量的气相色谱方法。与GB 5009.270—2016第二法相比,该方法改进了提取溶剂、提取方式、样品净化方式、滤液除水干燥方式、衍生试剂的添加顺序和添加比例,缩短了烘箱中的干燥时间及水浴衍生时间,并优化仪器色谱条件。研究结果表明,改进后的方法检出限为1 μg/mL;三水平加标回收率范围为97.4%~100.5%;重现性好,其测定结果的相对偏差＜2.1%;更简化了样品前处理操作,缩短了仪器分析时间,由国标法的63 min缩短至20 min,能够实现批量化处理,满足实验室大批量样品的检测需求。     

高效液相色谱法测定婴儿配方奶粉中乳糖和蔗糖含量的前处理方法优化

目的优化GB 5413.5-2010《食品安全国家标准婴幼儿食品和乳品中乳糖、蔗糖的测定》(第一法)中前处理步骤。方法样品先用15 mL热水溶解,再加入乙酸锌、亚铁氰化钾溶液各2 mL,涡旋振荡超声,加水定容到50 mL,离心过滤,最终通过高效液相色谱仪测定。结果测定乳糖含量较低的样品时,国标测定的结果与本方法相近,2种方法的相对标准偏差为0.22%。国标方法的样品加标回收率为99.0%,本方法为99.7%。本方法样品重复6次,蔗糖重复性的相对标准偏差为0.593%,乳糖为1.24%。当国标方法测定乳糖含量较高的样品时,会出现糖析出的问题,测得乳糖的含量远低于本方法。结论本方法解决了国标前处理出现的样品糖析出问题。研究结果表明本方法的精密度高、准确度高,线性范围良好,操作简单,是测定婴儿配方奶粉中蔗糖和乳糖含量的有效方法。     

试剂盒法快速检测婴幼儿乳粉及功能饮料中维生素B12的研究

目的建立试剂盒法快速检测婴幼儿乳粉及功能饮料中维生素B_(12)的含量。方法以Tris缓冲液稀释样品,加入冻干的莱士曼氏乳酸杆菌测试菌球,采用Costar 3599细胞培养板培养,使用酶标仪测定结果。采用本法同时检测了47批次婴幼儿乳粉和12批次功能饮料中维生素B_(12)的含量。结果本试剂盒方法回收率为89.9~110.2%,定量检测限为0.01 ng/g(mL),日间精密度为9.0%,日内精密度为5.8%。采用试剂盒方法与GB5413.14-2010试管法同时检测47批次婴幼儿乳粉中维生素B_(12)的含量,检测结果无显著性差异,乳粉的合格率为80.9%。检测功能性饮料12批次,合格率为33.3%。结论该方法操作简单,灵敏度高,重现性好,可用于测定婴幼儿乳粉及功能性饮料中维生素B_(12)的含量。     

Lactobacillus reuteri-fortified camel milk infant formula: Effects of encapsulation,in vitro digestion,and storage conditions on probiotic cell viability and physicochemical characteristics of infant formula

Lactobacillus reuteri fortified camel milk infant formula (CMIF) was produced. The effect of encapsulation in different matrices (sodium alginate and galacto-oligosaccharides) via spray drying, simulated infant gastrointestinal digestion (SIGID), and storage conditions (temperature and humidity) on the viability of L. reuteri in CMIF and the physicochemical properties of CMIF were evaluated. Compared with free cells, probiotic cell viability was significantly enhanced against SIGID conditions upon encapsulation. However, L. reuteri viability in CMIF decreased after 60 d of storage, predominantly at higher storage humidity and temperature levels. At the end of the storage period, significant changes in the color values were observed in all CMIF, with a reduction in their greenness, an increase in yellowness, and a wide variation in their whiteness. Moreover, pH values and caking behavior of all CMIF stored at higher temperature (40°C) and humidity [water activity (a_w) = 0.52] levels were found to be significantly higher than the samples stored under other conditions. Over 30 d of storage at lower humidity conditions (a_w = 0.11 and 0.33) and room temperature (25°C), no significant increase in CMIF lipid oxidation rates was noted. Fourier-transform infrared spectroscopy analysis showed that, compared with the other storage conditions, CMIF experienced fewer changes in functional groups when stored at a_w = 0.11. Microscopic images showed typical morphological characteristics of milk powder, with round to spherical-shaped particles. Overall, camel milk fortified with encapsulated L. reuteri can be suggested as a promising alternative in infant formula industries, potentially able to maintain its physicochemical characteristics as well as viability of probiotic cells when stored at low humidity levels (a_w = 0.11) and temperature (25°C), over 60 d of storage.