Development of Glycerol Trioleate/Glycerol Tristearate Solid Fat Content Reference Materials for Low Field Nuclear Magnetic Resonance
-
摘要: 固体脂肪含量是描述可可脂、人造黄油等油脂的重要质量指标。低场核磁共振法由于具有简单、快速、无需化学试剂等优点,已逐渐成为测量固体脂肪含量的主流手段。低场核磁共振直接法是一种相对方法,需要将仪器溯源至三油酸/三硬脂酸甘油酯混合物的固体脂肪含量。本文对低场核磁与测量固体脂肪含量的原理进行了介绍,研究了其定值溯源路径与三油酸/三硬脂酸甘油酯固体脂肪含量标准物质在不同温度下的稳定性,对比了混合油管在不同温度条件下测量不准确的原因,并最终确定了标准物质的定值方法与温度。Abstract: Low field nuclear magnetic resonance has gradually become the mainstream method for measuring solid fat content, which is an important index to qualify cocoa butter, margarine and other oils because it is simple, rapid and solvent free. However, Low field nuclear magnetic resonance direct method is a relative method, which requires the instrument to be calibrated using a glycerol trioleate/glycerol tristearate mixture. In this paper, the development and the principle of Low field NMR are introduced, the traceability and the stability of the glycerol trioleate/glycerol tristearate solid fat content reference material are studied, the measurement in different temperature are compared and the determination of the value was confirmed.
-
表 1 塑料/油管的均匀性
Table 1. The homogeneity of the plastic in oil tube
管1 管2 管3 管4 平均SFC 28.0% 43.3% 56.0% 72.0% 标准偏差 0.2% 0.2% 0.2% 0.1% 表 2 不同温度下用低场核磁间接法的测量结果
Table 2. Measurement results in different temperature by LFNMR direct method.
温度/℃ 测量
值/%测量
值/%测量
值/%测量
值/%测量
值/%测量
值/%配置值 0.0 20.5 35.0 51.2 70.6 86.8 10 0.2 23 37.9 56.8 75.1 89.7 20 0.3 22.2 37.1 55.4 73.7 89.4 32 0 21.4 36.1 54.1 72.3 88.7 表 3 标准物质候选物定值结果
Table 3. Certification result of the RM candidate
重复次数 B管SFC C管SFC 重复次数 B管SFC C管SFC M1 33.56% 69.98% N1 33.63% 69.88% M2 33.79% 70.00% N2 33.77% 69.94% M3 33.55% 69.87% N3 33.80% 69.88% M4 33.76% 69.94% N4 33.66% 69.90% M5 33.67% 70.01% N5 33.80% 70.07% M6 33.65% 69.91% N6 33.65% 70.00% 平均值 33.66% 69.95% 平均值 33.72% 69.95% 标准偏差 0.10% 0.05% 标准偏差 0.08% 0.07% 表 4 固体脂肪含量标准物质不确定度及其来源
Table 4. The uncertainty and its source of the SFC reference material
固体脂
肪含量重复性引入的
不确定度($u_{\rm{r}} $)测量过程引入的
不确定度($u_{SFC} $)均匀性引入的
不确定度($u_{\rm{h} }$)稳定性引入的不
确定度($u_{s_1}$)短期稳定性引入
的不确定度($u_{s_2}$)合成不确
定度($u_{\rm{c}} $)A管 0.00% 0.00% 0.00% 0.10% 0.28% 0.18% 0.35% B管 33.69% 0.17% 2.16% 0.02% 0.13% 0.16% 2.18% C管 69.95% 0.16% 4.83% 0.04% 0.20% 0.15% 4.84% 表 5 校正因子f值统计
Table 5. The statics of the correction factor f
管1 管2 管3 管4 校正因子f 1.51 1.51 1.44 1.35 -
[1] Davenel A, Riaublanc A, Marchal P. Quality of pig adipose tissue: relationship between solid fat content and lipid composition[J]. Meat Science, 1999, 51(1): 73-79. doi: 10.1016/S0309-1740(98)00099-0 [2] Augusto P E D, Soares B M C, Chiu M C, et al. Modelling the effect of temperature on the lipid solid fat content (SFC)[J]. Food Research International, 2012, 45(1): 132-135. doi: 10.1016/j.foodres.2011.10.026 [3] Van Putte K, Van Den Enden J. Fully automated determination of solid fat content by pulsed NMR[J]. Journal of the American Oil Chemists' Society, 1974, 51(7): 316-320. doi: 10.1007/BF02633005 [4] Gribnau, M C M. Determination of solid/liquid ratios of fats and oils by low-resolution pulsed NMR[J]. Trends in Food Science & Technology, 1992, 3(8): 186-190. [5] 肖新生, 杨交如, 唐满生, 等. 核磁共振技术在食用油脂分析中的应用研究进展[J]. 中国油脂, 2018, 43(12): 134-139. doi: 10.3969/j.issn.1003-7969.2018.12.031 [6] 刘纯友, 马美湖, 王庆玲, 等. 核磁共振技术在食品脂质研究中的应用新进展[J]. 食品工业科技, 2017, 38(12): 342-346. [7] Arnout D, Veronique N, Tom R, et al. Influence of Polymorphism on the Solid Fat Content Determined by FID Deconvolution[J]. European Journal of Lipid Science and Technology, 2017: 1700339. [8] Mills B L, Voort F. Determination of solid fat index of fats and oils using the anton paar density meter[J]. Journal of the American Oil Chemists' Society, 1981, 58(5): 618-621. doi: 10.1007/BF02672377 [9] Laubli M W, Bruttel P A. Determination of oxidative stability of fats and oils - comparison between the active oxygen method (aocs-cd-12-57) and the rancimat method[J]. Fett/Lipid, 1987, 89(11): 425-425. [10] Márquez, Andrés L, Pérez, et al. Solid Fat Content Estimation by Differential Scanning Calorimetry: Prior Treatment and Proposed Correction[J]. Journal of the American Oil Chemists' Society, 2013, 90(4): 467-473. doi: 10.1007/s11746-012-2190-z [11] Tieko Nassau, Renata, Guaraldp Gonçalves, Lireny Aparecida. Solid fat content determination: Comparison between pNMR and DSC techniques[J]. Grasasy Aceites, 1995, 46(6): 337-343. doi: 10.3989/gya.1995.v46.i6.949 [12] 国家市场监督管理总局. 动植物油脂 冲核磁共振法测定固体脂肪含量 直接法: GB/T 31743-2015[S]. 北京: 中国标准出版社, 2015. [13] 国家市场监督管理总局. 动植物油脂 脉冲核磁共振测定 固体脂肪含量 间接法: GB/T 37517-2019 [S]. 北京: 中国标准出版社, 2019. [14] AOCS. Solid Fat Content (SFC) by Low-Resolution Nuclear Magnetic Resonance—The Direct Method: AOCS method Cd 16b-93 [S]. America: AOCS , 2009. [15] ISO. Animal and vegetable fats and oils — Determination of solid fat content by pulsed NMR — Part 1: Direct method: ISO 8292-1[S]. ISO, 2008. [16] ISO. Animal and vegetable fat and oils – sampling: ISO 5555[S]. ISO, 1991. [17] 蒲成, 任玲玲. 高分子化合物的分子量表征[J]. 计量科学与技术, 2021, 65(1): 34-39. [18] 郭士刚, 凌凤香, 高旭锋. 红外光谱法测定柴油中脂肪酸甲酯的检出限及不确定度评定[J]. 计量学报, 2021, 42(8): 1115-1120. doi: 10.3969/j.issn.1000-1158.2021.08.21 -