Guo Xiao-Xi, Hu Wei, Liu Yuan, Sun Su-Qin, Gu Dong-Chen, He Helen, Xu Chang-Hua, Wang Xi-Chang
College of Food Science & Technology, Shanghai Ocean University, Shanghai 201306, PR China.
Analysis Center, Tsinghua University, Beijing 100084, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2016 Feb 5;154:123-129. doi: 10.1016/j.saa.2015.10.017. Epub 2015 Oct 24.
BPO is often added to wheat flour as flour improver, but its excessive use and edibility are receiving increasing concern. A multi-step IR macro-fingerprinting was employed to identify BPO in wheat flour and unveil its changes during storage. BPO contained in wheat flour (<3.0 mg/kg) was difficult to be identified by infrared spectra with correlation coefficients between wheat flour and wheat flour samples contained BPO all close to 0.98. By applying second derivative spectroscopy, obvious differences among wheat flour and wheat flour contained BPO before and after storage in the range of 1500-1400 cm(-1) were disclosed. The peak of 1450 cm(-1) which belonged to BPO was blue shifted to 1453 cm(-1) (1455) which belonged to benzoic acid after one week of storage, indicating that BPO changed into benzoic acid after storage. Moreover, when using two-dimensional correlation infrared spectroscopy (2DCOS-IR) to track changes of BPO in wheat flour (0.05 mg/g) within one week, intensities of auto-peaks at 1781 cm(-1) and 669 cm(-1) which belonged to BPO and benzoic acid, respectively, were changing inversely, indicating that BPO was decomposed into benzoic acid. Moreover, another autopeak at 1767 cm(-1) which does not belong to benzoic acid was also rising simultaneously. By heating perturbation treatment of BPO in wheat flour based on 2DCOS-IR and spectral subtraction analysis, it was found that BPO in wheat flour not only decomposed into benzoic acid and benzoate, but also produced other deleterious substances, e.g., benzene. This study offers a promising method with minimum pretreatment and time-saving to identify BPO in wheat flour and its chemical products during storage in a holistic manner.
过氧化苯甲酰（BPO）常作为面粉改良剂添加到小麦粉中，但其过量使用及食用安全性日益受到关注。采用多步红外宏观指纹图谱法鉴定小麦粉中的BPO，并揭示其在储存过程中的变化。小麦粉中含量低于3.0 mg/kg的BPO难以通过红外光谱鉴定，含BPO的小麦粉样品与普通小麦粉的相关系数均接近0.98。通过二阶导数光谱分析，发现在1500 - 1400 cm⁻¹范围内，储存前后含BPO的小麦粉与普通小麦粉存在明显差异。储存一周后，属于BPO的1450 cm⁻¹处的峰蓝移至属于苯甲酸的1453 cm⁻¹（1455）处，表明储存后BPO转变为苯甲酸。此外，利用二维相关红外光谱（2DCOS - IR）跟踪小麦粉（0.05 mg/g）中BPO在一周内的变化，属于BPO和苯甲酸的1781 cm⁻¹和669 cm⁻¹处的自动峰强度呈反向变化，表明BPO分解为苯甲酸。此外，不属于苯甲酸的1767 cm⁻¹处的另一个自动峰也同时上升。基于2DCOS - IR和光谱减法分析对小麦粉中的BPO进行加热扰动处理，发现小麦粉中的BPO不仅分解为苯甲酸和苯甲酸盐，还产生了其他有害物质，如苯。本研究提供了一种预处理最少且省时的有前景的方法，以整体方式鉴定小麦粉及其储存过程中的化学产物中的BPO。
