The ARC Dairy Innovation Hub, The Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia; The Bio21 Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.
Infrared Microspectroscopy (IRM) Beamline, Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia.
Food Chem. 2019 Sep 1;291:214-222. doi: 10.1016/j.foodchem.2019.04.016. Epub 2019 Apr 4.
Synchrotron Fourier transform infrared (S-FTIR) microspectroscopy allows the label-free examination of material microstructure but has not been widely applied to dairy products. Here, S-FTIR microspectroscopy was applied to observe the microstructure of Mozzarella cheese and assess the protein and lipid distribution within individual cheese blocks. High lipid and high protein areas were identified in transmission and attenuated total reflectance (ATR) analysis modes and the secondary structures of cheese proteins determined. Hierarchical cluster analysis and principal component analysis identified variation in random coil, water content, lipid carbonyl and methylene stretching across the sampled area. Similar spectral features were obtained in both analysis modes; spatial resolution was higher with ATR and small differences were noted, potentially as a result of differences in sample preparation. S-FTIR is a useful microscopy tool that can detect structural alterations that may affect product properties and may assist reverse engineering of a range of dairy products.
同步辐射傅里叶变换红外（S-FTIR）微光谱技术可用于对材料微观结构进行无标记检测，但尚未广泛应用于乳制品。本研究采用 S-FTIR 微光谱技术观察马苏里拉奶酪的微观结构，并评估单个奶酪块内的蛋白质和脂肪分布。透射和衰减全反射（ATR）分析模式下鉴定出高脂质和高蛋白区域，并确定了奶酪蛋白质的二级结构。层次聚类分析和主成分分析确定了在所研究区域内随机卷曲、水分含量、脂质羰基和亚甲基拉伸的变化。两种分析模式均获得相似的光谱特征；ATR 具有更高的空间分辨率，并且注意到细微差异，这可能是由于样品制备的差异所致。S-FTIR 是一种有用的显微镜工具，可检测可能影响产品特性的结构变化，并可能有助于一系列乳制品的反向工程。
