Mazurek Sylwester, Szostak Roman, Kondratowicz Mateusz, Węglińska Magdalena, Kita Agnieszka, Nemś Agnieszka
Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland.
Department of Food Storage and Technology, Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, 37 Chełmońskiego, 51-630 Wrocław, Poland.
Antioxidants (Basel). 2021 Jul 14;10(7):1123. doi: 10.3390/antiox10071123.
An application of solid C nuclear magnetic resonance (NMR) spectroscopy for the determination of macronutrients, total polyphenols content, antioxidant activity, N C S elements, and pH in commercially available bee pollens is reported herein. Solid-state C NMR spectra were recorded for homogenized pollen granules without chemical treatment or dissolution of samples. By combining spectral data with the results of reference analyses, partial least squares models were constructed and validated separately for each of the studied parameters. To characterize and compare the models' quality, the relative standard errors of prediction (RSEP) were calculated for calibration and validation sets. In the case of the analysis of protein, fat and reducing sugars, these errors were in the 1.8-2.5% range. Modeling the elemental composition of bee pollen on the basis of C NMR spectra resulted in RSEP/RSEP values of 0.3/0.6% for the sum of NHCS elements, 0.3/0.4% for C, 1.8/1.9% for N, and 4.2/6.1% for S quantification. Analyses of total phenolics and ABTS antioxidant activity resulted in RSEP values in the 2.7-3.5% and 2.8-3.8% ranges, respectively, whereas they were 1.4-2.1% for pH. The obtained results demonstrate the usefulness of C solid-state NMR spectroscopy for direct determination of various important physiochemical parameters of bee pollen.
本文报道了固态碳核磁共振（NMR）光谱法在测定市售蜂花粉中的常量营养素、总多酚含量、抗氧化活性、氮、碳、硫元素及pH值方面的应用。在未经化学处理或溶解样品的情况下，对匀质化的花粉颗粒记录固态碳NMR光谱。通过将光谱数据与参考分析结果相结合，针对每个研究参数分别构建并验证了偏最小二乘模型。为了表征和比较模型质量，计算了校准集和验证集的预测相对标准误差（RSEP）。在蛋白质、脂肪和还原糖分析中，这些误差在1.8 - 2.5%范围内。基于碳NMR光谱对蜂花粉的元素组成进行建模，得到氮、氢、碳、硫元素总和的RSEP/RSEP值为0.3/0.6%，碳为0.3/0.4%，氮为1.8/1.9%，硫定量为4.2/6.1%。总酚和ABTS抗氧化活性分析得到的RSEP值分别在2.7 - 3.5%和2.8 - 3.8%范围内，而pH值的RSEP值为1.4 - 2.1%。所得结果证明了固态碳NMR光谱法在直接测定蜂花粉各种重要理化参数方面的实用性。
