米饭变质过程的红外光谱分析

Infrared spectrum analysis on the rice deterioration process

利用傅里叶变换红外光谱(FTIR)技术、二维相关红外光谱(2D-IR)技术和PH计对米饭变质过程进行了研究。结果显示米饭变质过程中p H值逐渐降低,酸性逐渐增强,红外光谱结果显示米饭放置1~5天的红外光谱大体相似。选取1800cm^(-1)至700cm^(-1)范围的二阶导数光谱进行比较,发现1120、1051、1022和962cm^(-1)的吸收峰随着时间的增加呈现出逐渐降低的规律性变化,特别是在1120和962 cm^(-1)处吸收峰变化明显,表明米饭在变质过程中内部的多糖含量发生变化。2D-IR技术在1410cm^(-1)至1670cm^(-1)和1010cm^(-1)至1110cm^(-1)范围内,放置不同时间的米饭的自动峰和交叉峰的强度、位置差异显著,1450、1560 cm^(-1)附近自动峰均在第二天出现,而且1450cm^(-1)强度先上升再降低,1100cm^(-1)自动峰强度逐渐降低,并且在第五天消失,表明米饭在变质过程中蛋白质、糖的含量发生变化。结果表明:运用FTIR、2D-IR技术对米饭变质过程的研究是一种行之有效的方法。

Using Fourier transform infrared spectroscopy（ FTIR） technology,two-dimensional correlation spectroscopy（ 2D-IR） technology and p H meter to analysis the deterioration process of cooked rice. The results showed that the PH value of the cooked rice was gradually decreased while the acidity was gradually increased. Infrared spectra of cooked rice within five days were similar. Compared the second derivative spectra in the range of 1800cm^-1 to 700cm^-1,found the absorption peaks of 1120,1051,1022,and 962 cm^-1decrease regularly with the increase of time,especially 1120 and 969 cm^-1. It shows the polysaccharide content is changing in the deterioration process. In 2D-IR between 1410cm^-1to 1670cm^-1 and 1010 cm^-1 to 1110 cm^-1,The intensity and position of automatic peak and crossed peak in different time had significant differences. The automatic peaks in 1450 and 1560 cm^-1 appeared in the second day and the strength in 1450cm^-1first increased and then decreased while that in 1100cm^-1 decreased gradually,and both disappeared in the fifth day. It shows that the protein and sugar content of cooked rice change in the deterioration process. The results shows that the FTIR and 2D-IR technology are practical to study the deterioration process of cooked rice.