冷鲜猪肉的三维荧光光谱特征研究

利用三维荧光光谱技术，研究了冷鲜猪肉三维荧光光谱特征，主要探讨了不同温度存储条件下冷鲜猪肉荧光峰的位置和荧光峰所处区域内荧光强度平均值随存储时间变化的规律，并初步判断了荧光物质的种类，为实现基于三维荧光光谱技术快速、无损检测冷鲜猪肉新鲜度奠定了理论基础。实验结果表明，不同温度存储条件下样本的三维荧光光谱图中均含有2个明显的荧光峰（Peak A和Peak B），它们所在位置的激发波长（λ_ex）/发射波长（λ_em）范围分别为：λ_ex/λ_em约为250～310 nm/300～400 nm和约为300～450 nm/400～550 nm。其中，Peak A为类蛋白荧光，Peak B为脂质氧化产物荧光。此外，实验还发现，两个荧光峰在各自所处区域内荧光强度的平均值随存储时间变化的趋势不受存储温度影响，均是Peak A在λ_ex/λ_em=250～310 nm/300～400 nm区域内荧光强度的平均值（I_A）逐渐下降，Peak B在λ_ex/λ_em=300～450 nm/400～550 nm区域内荧光强度的平均值（I_B）逐渐上升。但I_A和I_B的变化速率受存储温度影响，冷藏条件下比室温条件下变化慢。

Characterization of Chilled Pork with Three-Dimensional Fluorescence Spectroscopy

Three-dimensional fluorescence spectroscopy was employed to investigate the fluorescence characteristic of chilled pork stored at different temperatures in this research. The locations of fluorescence peaks were identified and the changes in the average intensity values of two fluorescence peaks in their respective regions during storage were traced. Initially the fluorescent substances were determined as a basis for realizing rapid non-destructive detection of chilled pork freshness with three-dimensional fluorescence spectroscopy. The results showed that three-dimensional fluorescence spectra of chilled pork samples showedfluorescence peaks of two types (Peak A and Peak B) regardless of the storage temperature. The excitation wavelength (λ_ex)/emission wavelength (λ_em) of Peak A was 250～310 nm/300～400 nm, whereas of Peak B was 300～450 nm/400～550 nm. Peak A and Peak B represented protein-like fluorescence and lipid oxidation products fluorescence, respectively. Moreover, the location of the maximum of Peak A was at λ_ex/λ_em=290 nm/335 nm during storage, while that of Peak B shifted from λ_ex/λ_em=320 nm/470 nm to λ_ex/λ_em=390 nm/470 nm. The results also indicated that the average intensity values of two fluorescence peaks in their respective regions had the same trend regardless of the storage temperature: the average intensity values of Peak A in the region of λ_ex/λ_em=250～310 nm/300～400 nm (I_A) was gradually declined, while that of Peak B in the region of λ_ex/λ_em=300~450 nm/400~550 nm (I_B) was gradually increased as time went by. However, the storage temperature determined the change rate of I_A and I_B: the samples stored at 20 ℃ had higher the rate of change than those stored at 4 ℃.