乳粉中矿物质检测稳定性分析研究

目的对乳粉中矿物质元素检测的稳定性进行分析研究。方法依据国标方法对GB 10765-2010中必需要求的12种矿物质元素进行检测,在同一实验室对同一乳粉中的矿物质元素进行重复检测确定产品的稳定性;在不同实验室对同一乳粉中的矿物质元素进行检测,发现实验室检测稳定性的差异。结果发现同一实验室对同一批次乳粉中矿物质元素检测的稳定性较好,不同实验室间矿物质元素检测稳定性相对较差。结论统一实验室检测方法,提升实验室检测水平,是确保检测稳定性的前提,有利于为企业生产时提供准确的检测数据,对制定产品配方具有重要指导意义。     

婴幼儿配方乳粉中维生素A、D的测定能力验证结果与分析

设计组织婴幼儿配方乳粉中维生素A、D测定的能力验证项目,分析各参加实验室的检测能力验证结果。采用单因素方差分析和t检验对样品均匀性和稳定性进行分析,对224家实验室提交的检测结果进行稳健统计分析,以相对相差评定各参加实验室测定结果。结果表明,样品均匀性和稳定性符合能力验证要求,维生素A的满意率为82.7%,维生素D的满意率为93.8%。多数参加实验室结果为满意,表明婴幼儿配方乳粉中维生素A、D检测水平总体良好。     

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。     

乳粉中维生素B1和B2含量测定的能力验证分析

目的为加强我国检测机构对乳粉市场的监管,中国食品药品检定研究院(National Institute for Food and Drug Control,NIFDC)组织实施了乳粉中维生素B_1和B_2的含量测定的能力验证。方法制备了分割水平对的样品,采用单因素方差分析和t检验对样品均匀性和稳定性进行分析。对能力验证结果进行稳健统计分析,通过Z比分数评价实验室检测能力。结果样品通过均匀性和稳定性检验要求,满足能力验证计划要求。维生素B_1项目中,参加20个实验室验证,满意结果数为14,满意率为70.0%;维生素B_2项目中,参加22个实验室验证,满意结果数为15,满意率为77.2%;2项检测结果均满意的实验室有12个,满意率为60%。结论绝大多数实验室对乳粉中维生素B_1和B_2的测定处于良好水平,但未达到优良水平,仍需对检测方法进行统一认识,减少系统误差,加强各实验室内部的质量控制。     

婴幼儿乳粉中维生素B_(12)检测的实验室间比对结果分析

通过婴幼儿乳粉中维生素B_(12)检测的实验室间比对,提高实验室对婴幼儿食品和乳粉中维生素B_(12)的检测能力。利用莱士曼氏乳杆菌对维生素B_(12)的特异性和灵敏性,定量测定试样C00076中维生素B_(12)的含量,并通过多种质量控制措施对测定结果进行分析评价。结果表明,本实验室检测结果为1.7μg/100 g,广州市食品检验所检测结果为1.7μg/100 g,再现性标准差为0。实验室间比对实验结果为满意,表明本实验室婴幼儿食品和乳粉中维生素B_(12)的测定能力良好,并对微生物方法提出改进建议,为今后维生素B_(12)的测定提供一定的参考。     

婴幼儿配方乳粉中维生素PP含量测定盲样考核研究

目的评价国家食品安全抽检监测承检机构实验室测定婴幼儿配方乳粉中维生素PP的技术能力和水平,分析存在的问题,以期提高其检验水平。方法具体实施婴幼儿配方乳粉中维生素PP含量测定盲样考核项目。制备2个浓度水平的考核样品,经均匀性检验和稳定性检验符合盲样考核要求,样品随机发放给23家单位实验室,其中1个样品作为考核样品进行结果统计分析,另一个样品作为干扰样。对参加该计划的23家单位的实验室测定结果进行稳健统计分析,用z比分数评价实验室检测能力。结果制备的样品均匀性符合要求且在整个计划周期内保持稳定,满足盲样考核要求。参加实验室上报的数据经分析,z比分数绝对值均小于2。结论 23家参加此次盲样考核项目的实验室评价均为满意,本项目检测水平总体良好。     

中性及酸性条件下不同来源脱脂乳粉的稳定性比较分析

目的对5种不同来源的脱脂乳粉在中性和酸性条件下的稳定性进行比较分析。方法对不同脱脂乳粉的营养组成、乳清蛋白氮、热凝固时间、△p H、离心沉淀率等指标进行检测并进行对比。结果 5种脱脂乳粉在蛋白质、乳糖、钙等影响稳定性的成分上差异不大,脱脂乳粉热凝固时间越长、△p H越小,酸性乳饮料经高温热处理后离心沉淀越少,而脱脂乳粉乳清蛋白氮越高,中性条件下离心沉淀越少。结论本研究对脱脂乳粉在中性和酸性条件下的稳定性评价较为科学,对于乳清蛋白氮、热凝固时间和△p H的测定可应用于产品中脱脂乳粉的选择。     

婴幼儿配方乳粉中磷质量分数的测定

为了准确测定婴幼儿配方乳粉中的磷质量分数,从方法的最佳实验条件、精密度、稳定性、重现性及回收率方面做了研究,发现采用可见分光光度法测定婴幼儿配方乳粉中的磷质量分数,重现性好,准确度高。建立了线性方程,方法的平均回收率为98.5%,RSD为0.39%。随机抽取市售的30批次婴幼儿配方乳粉进行检测,发现不同阶段的乳粉磷质量分数不同,幼儿配方乳粉较大婴儿配方乳粉婴儿配方乳粉,分别为(448±56)mg/g,(382±59)mg/g,(250±58)mg/g,不同品牌同一阶段的乳粉磷质量分数也存在较大差异。     

关于乳粉中钙元素质控样品的研制及应用

该质控样品可广泛用于乳制品实验室乳粉中钙的含量测定、质量控制及检测项目的开展等。利用实验室日常检测乳粉样品进行乳粉中钙元素实物质控样品的制备,采用分装设备进行分装和包装、均匀性及稳定性统计学评价,实物质控样品赋值的研究、不确定度的确定。最终应用于企业实验室日常实验室质量控制、方法验证证实、期间核查等方面,质控样品的基质和企业实验室日常检测样品基质一致,检测结果更具有代表性。     

婴幼儿配方乳粉中脂溶性维生素的稳定性探究

为探讨婴幼儿配方乳粉中脂溶性维生素在贮存过程中的稳定性,跟踪研究了婴幼儿配方乳粉在42℃和50℃条件下,贮存6个月,维生素A、D、E、K1的衰减情况。结果,婴幼儿配方乳粉贮存温度越高脂溶性维生素的稳定性越差,且脂溶性维生素的稳定性还受乳粉配方组成的影响。在6个月的贮存过程中,维生素D和K1稳定性高于维生素A和E,维生素A,D,K1,E的最高损失率分别为14.8%,5.6%,9.2%和11.6%。     

Development of methods for the determination of vitamins A, E and β-carotene in processed foods based on supercritical fluid extraction: a collaborative study

New methodologies based on supercritical fluid extraction (SFE) have been developed for the determination of fat-soluble vitamins in processed foods. The results obtained so far indicate that SFE is well suited to extraction of fat-soluble vitamins from food products, although validation work is required to establish accuracy and precision. The vitamins investigated were A, E and β-carotene, and the processed foods were UHT milk, milk powder, minced meat, liver paste, infant formula, canned baby food and margarine. Extraction equipment employed analyte collection on either a solid-phase trap or in a solvent. After extraction, the samples were saponified and the vitamins determined using reversed-phase liquid chromatography with ultraviolet or fluorescence detection. Sample throughput was at least 12 samples day -1 , i.e. at least twice the number achievable with a conventional extraction methodology. The detection limits for the vitamins in different processed foods were well below 0.1 µg g -1 . Recoveries (in comparison with vitamin levels obtained using conventional solvent extraction) were close to 100% for experienced personal with access to modern automatic equipment. To reach this level, it was necessary to protect the vitamins with an antioxidant during the different steps of the analysis procedure, to add methanol or ethanol to the extraction cell to facilitate the analyte extraction from the food matrix, and when using a solid-phase trap, to employ a fractionated extraction-elution procedure to prevent breakthrough losses. The developed methods were tested in a validation exercise between five laboratories, which had taken part in the method development, and in an intercomparison between 10 laboratories including laboratories with less experience of vitamin determination. The within-laboratory RSD was generally ≤11%. The average of the between-laboratory relative standard deviation (RSD) was about 23% in the validation, and increased to about 40% in the intercomparison. Ruggedness tests performed at different steps of the project showed that different types and models of equipment did not give large differences in recoveries. Thus, the increasing RSD can largely be ascribed to differences in experience in vitamin analysis of the participants.     

微孔板法检测婴幼儿配方乳粉中维生素B12的含量

目的 建立用微孔板检测婴幼儿配方乳粉中维生素B12的方法。方法 基于微生物原理的检测方法, 缩小样品的培养体积。样品经提取后, 分装到96孔细胞培养板中, 在培养基中加入0.05%的菌悬液, 混匀后分配到含有样品和标准品的微孔中, 培养后直接用酶标仪测定吸光度值。结果 本方法标准曲线相关系数0.9987, 加标回收实验回收率在92.7%~98.7%之间, 重复性实验相对标准偏差在1.03%~1.73%之间, 6种不同含量的样品同时用GB 5413.14-2010方法和本方法检测维生素B12, 检测结果无显著性差异。结论 该方法快速, 操作简单, 稳定性高, 检测成本低, 可大批量样品同时检测, 适合测定婴幼儿配方乳粉中维生素B12的含量。     

乳粉中三聚氰胺标准物质的制备

目的制备乳粉中的三聚氰胺标准物质。方法将三聚氰胺标准溶液与乳粉复溶液通过均质、冷冻干燥、粉碎、过筛、混合等步骤制得标准物质,经均匀性与稳定性研究,由8家实验室进行协同定值,并进行不确定度评估。结果制得的标准物质的特性值为(5.19±0.37) mg/kg,均匀性良好,稳定性大于12个月。结论通过该方法制得的标准物质,均匀性与稳定性良好。可用于检测方法的开发、检测过程的质量控制、实验室能力验证、实验室间比对等领域。     

维蔬奶香糖的制造技术

维蔬奶香糖是一种在传统硬糖基础上，采用新鲜牛奶和新鲜蔬菜粉，同时强化维生素Ｃ生产的糖果新产品。本文从配料选择、生产工艺等角度，着重探讨营养强化及稳定性控制等制造技术。     

Determination of vitamin D in food using high performance liquid chromatography (HPLC). Results of collaborating studies of the working group "Vitamin Analysis" according to section 35 of the German Food Act]

A standardized method to determine the vitamin D content of food by means of HPLC is described. After the test material was homogenized and saponified with ethanolic aqueous potassium hydroxide solution, vitamin D was extracted using n-hexane. Using HPLC on a silica gel column, the fraction containing vitamin D is separated from the nonsaponifiable residue. After the fraction was reduced, the residue was dissolved in methanol and the vitamin D content determined after HPLC separation on an RP-C18 column. For evaluation, either a conventional external standard method using laboratory and matrix specific recovery rates as correction factors, or an internal standard method using vitamin D2, and D3, respectively as internal standards were employed. The method was developed and standardized by the working group "Vitamin Analysis" in accordance with section 35 LMBG (German Food Act). Repeatability and comparability of the results were checked in collaborative studies (14 laboratories) in milk powder and gruel that had been enriched with vitamin D3. Applicability of the method to other food (eggs, milk, fish, margarine) was checked separately. The statistical evaluation of the results of the collaborative studies has shown that the method is reliable enough to be included into the "Amtliche Sammlung" (official collection of analytical methods) according to section 35 LMBG. The present method may be used to determine the content of vitamin D2 and D3 in natural and vitaminized food. It is specific for the vitamins D2 and D3 released during saponification of food, but does not allow separate determination of the pre-vitamins D already present in the sample.     

沸石粉中重金属及以沸石粉为载体维生素预混合饲料含量实验室间比对结果评价

全国共26家省市饲料检测机构、第三方检测机构以及饲料生产企业检验化验室参加了沸石粉中重金属及以沸石粉为载体的维生素预混合饲料中维生素检测实验室间比对.通过采用四分位稳健统计法处理各实验室的检测数据,同时通过上交原始记录分析了各实验室质量管理体系运行中存在的问题,检测方法及前处理选择、质控环节的问题是较为突出的问题.针对...