近红外光谱法快速检测婴儿配方奶粉中的脂肪酸含量

采用傅里叶近红外光谱结合偏最小二乘法(PLS)法建立了测定婴儿配方奶粉中的总脂肪酸、饱和脂肪酸和不饱和脂肪酸含量的近红外数学模型,并通过交互验证和外部检验两种方式考察了近红外数学模型的可靠性。通过选择不同的波长范围,采用平滑、矢量归一化、一阶求导、二阶求导和散射校正对近红外光谱进行处理,总脂肪酸、饱和脂肪酸和不饱和脂肪酸的校正模型相关系数(R2)分别为0.9337、0.9374、0.9020,RPD分别为3.63、3.65、2.90。结果表明近红外数学模型具有良好的预测性能。采用建立的模型对验证集中的20个婴儿配方奶粉样品进行预测,总脂肪酸含量、饱和脂肪酸和不饱和脂肪酸的预测值与化学测定值之间经配对t检验分析,与常规化学方法得到的检验结果无显著差异。     

姜汁花生奶复合饮料的研究

研究了姜汁花生奶的工艺路线、关键工艺参数、配方以及稳定性。姜汁花生奶具有生姜和花生的复合风味。是一种高营养、新口味的新型保健复合植物蛋白饮料。为该产品的工业化生产提供参考和理论基础。     

活性焦脱硫体系床层阻力试验研究及拟合计算

对活性焦堆积模型进行求解,获得了活性焦床层阻力理论计算公式。在此基础上构建活性焦床层阻力试验系统,在流体介质为空气的条件下,对2种常用活性焦进行了阻力测试。将测试结果通过线性拟合,获得2种活性焦的床层阻力计算一般性经验公式为Δp/uL=3 742u+704和Δp/uL=2 212u+303。经试验验证,绝大部分床层阻力的理论值与试验值的误差小于3%,表明上述公式准确、可靠。但在实际工程应用中,活性焦的床层阻力计算公式还应进行适当的修正。     

乳汁中的寡糖及在乳品工业中的应用

母乳中的寡糖大约占总糖的10％，根据其核心结构不同可分为12类，其寡糖组分随哺乳期的变化而改变。母乳中的寡糖具有独特的生理功能，对于婴儿的神经系统发育、预防感染和促进正常的肠道微生物生态形成等非常重要，是保证婴儿健康成长的关键因素．目前用于婴儿乳添加剂的寡糖主要有寡聚果糖和寡聚半乳糖。本文讨论了母乳寡糖的结构、消化吸收、生理作用和在乳品工业中的应用。     

关于三次高斯和及其四次均值

研究三次高斯和的均值性质，并给出一个精确的计算公式。     

Multiclass and multi-residue screening of mycotoxins,pharmacologically active substances,and pesticides in infant milk formulas through ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry analysis

Infant milk formulas are designed to substitute human milk when breastfeeding is unavailable. In addition to human milk and milk-derived products, these formulas can be a vehicle of contaminants. In this work, a multiclass method based on the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach was developed for the simultaneous determination of contaminants (n = 45), including mycotoxins and veterinary drug residues, occurring in infant milk formulas. By using an ultra-high-performance liquid chromatography quadrupole-Orbitrap coupled with high-resolution mass spectrometry analysis (UHPLC-Q-Orbitrap HRMS; Thermo Fisher Scientific), further retrospective analysis of 337 contaminants, including pesticides, was achieved. The method was validated in accordance with European regulations and applied for the analysis of 54 infant milk samples. Risk assessment was also performed. Dexamethasone was detected in 16.6% of samples (range: 0.905–1.131 ng/mL), and procaine benzyl penicillin in 1 sample at a concentration of 0.295 ng/mL. Zearalenone was found in 55.5% of samples (range: 0.133–0.638 ng/mL) and α-zearalenol in 16.6% of samples (range: 1.534–10.408 ng/mL). Up to 49 pesticides, 11 veterinary drug residues, and 5 mycotoxins were tentatively identified via retrospective analysis based on the mass spectral library. These findings highlight the necessity of careful evaluation of contaminants in infant formulas, considering that they are intended for a vulnerable part of the population.     

Theoretical Prediction of Expansion History of Metal Cylinder for Multicomponent Explosives

As a traditional experimental approach, the cylinder test has been widely applied to evaluate the ability to accelerate metal, acquire the specific dynamic energy, and calibrate the equation of state of the detonation product for an explosive. In this article, based on the constant metal-density Gurney formula, a theoretical approach to predicting the expansion history of a metal cylinder shell driven by the detonation product of a multicomponent explosive under any explosive mixture ratio is proposed, providing that the corresponding theoretical density and the initial internal energy and the Jones-Wilkins-Lee parameters of each explosive component in the multicomponent explosive are known. Based on this predicted expansion history, the ability to accelerate metal, the specific dynamic energy, and the equation of state of a multicomponent explosive under any explosive mixture can all be acquired without an extra cylinder test for the multicomponent explosive itself. For verification, numerical results for the expansion histories of a copper cylinder driven by the detonation products of a PBX-C03 and a Comp-B multicomponent explosive were calculated and found to be in reasonably good agreement with previous cylinder test data.     

婴幼儿配方乳粉中污染物风险评估体系的探讨

在国内外婴幼儿配方乳粉安全问题频发的背景下, 针对乳粉的污染物风险分析并进行评估在保障食品安全方面有着极为重要的意义。本文以婴幼儿配方乳粉为研究对象, 分别从原料、加工和包装环节对污染物的风险评估进行探讨, 探讨内容包括了原料乳中常见的微生物污染, 乳粉加工过程中可能存在的各类元素或重金属污染, 以及包装过程中存在的化学物质迁移。同时结合并对比国内外的相关评估理论及食品安全标准, 对可能存在的风险来源进行了探讨, 为婴幼儿配方乳粉中污染物的风险评估体系的完善提供了思路。     

气相色谱-串联质谱法测定婴幼儿配方奶粉中氯丙醇酯和缩水甘油酯

目的 采用气相色谱-串联质谱(gas chromatography-tandem mass spectrometry,GC-MS/MS)技术,实现对婴幼儿配方奶粉中3-氯-1,2-丙二醇脂肪酸酯(3-monochloropropane-1,2-diol ester,3-MCPDE)、2-氯-l,3-丙二醇脂肪酸酯(2-monochloropropane-1,3-diol ester,2-MCPDE)和缩水甘油脂肪酸酯(glycidol fatty acid esters, GEs)的准确定性和定量。方法 从奶粉样品中提取的脂肪经溴代反应后,其中的缩水甘油酯转变成溴丙醇酯。溴丙醇酯和样品中的氯丙醇酯在酸性条件下发生酯交换反应,溴丙醇酯被水解为游离态形式的3-溴-1,2-丙二醇(3-MBPD)、氯丙醇酯被水解为游离态形式的氯丙醇(3-MCPD、2-MCPD);水解液经碱中和后,经硅藻土固相萃取小柱净化,洗脱液脱水后氮吹浓缩,再经七氟丁酰基咪唑(HFBI)衍生;衍生液用异辛烷定容后供GC-MS/MS分析,采用同位素内标法定量,可一次性同时测定奶粉中3-MCPDE、2-MCPDE和GEs的含量。结果 该方法在20～600 ng/mL范围内线性良好(r_²≥0.99),检出限为0.005 mg/kg脂肪,定量限为0.015 mg/kg脂肪,检出限和定量限均以相应的氯丙醇或缩水甘油计。0.1、0.5 mg/kg和1.0 mg/kg水平下的加标回收率在89.7%～105.6%之间,相对标准偏差均不大于5.56%。结论 该方法灵敏、准确可靠,适合婴幼儿配方奶粉中3-MCPDE、2-MCPDE和GEs的同时测定。     

高效液相色谱法检测婴幼儿配方食品中维生素B12的含量

目的 建立一种高效液相色谱快速检测婴幼儿配方食品中维生素B12的方法。方法 选择C18柱（250×4.6mm,4.6 μm）作为色谱柱,流动相为水-甲醇（75:25）,流速0.5 mL/min等度洗脱,进样量35 μL,柱温40℃,波长361nm,样品经超声提取15 min,然后在8000 r/min下冷冻离心10 min,离心结束后取上清液过0.22 μm滤膜,上机测试。结果 显示维生素B12标准品在浓度0.05~2.0 μg/mL范围内线性良好;相关系数r=0.9998;平均回收率91.3 %;检出限2 ng/mL。结论 该条件下的高效液相色谱可测定婴幼儿配方食品中维生素B12含量,具有重复性好、简单、快速、结果准确等优点。因此该方法可应用于婴幼儿配方食品中维生素B12含量的检测。