Utilization of fourier transform infrared spectroscopy for measurement of organic phosphorus and bound calcium in cheddar cheese.
Utilization of fourier transform infrared spectroscopy for measurement of organic phosphorus and bound calcium in cheddar cheese.
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DOI：
10.3168/jds.s0022-0302(06)72260-3
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发表时间：
2006-06
影响因子：
3.5
通讯作者：
P. Upreti;Lloyd Metzger
中科院分区：
文献类型：
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作者：
P. Upreti;Lloyd Metzger
现有的测量奶酪中有机磷和结合钙的方法要么繁琐，要么需要稀释奶酪。奶酪的稀释可能导致错误的结果，特别是在结合Ca的情况下。因此，本研究的目的是评估傅里叶变换红外（FTIR）光谱直接测量切达奶酪中有机P和结合Ca的可行性。对216份奶酪样品进行了蛋白质结合有机磷、结合钙的分析，采用基于水萃取的方法和缓冲曲线。此外，奶酪的红外光谱在4000到650厘米（-1）之间收集，分辨率为4厘米（-1），每个样品进行256次扫描。利用红外光谱从1050到900 cm（-1）的位移，以及pH 5.1下有机磷、结合钙和缓冲峰面积的测量浓度，利用偏最小二乘（PLS）回归分析建立校准模型。光谱区域956 ~ 946 cm（-1）与有机磷的实测浓度相关，总体PLS模型预测浓度与实测浓度的相关系数（R2）为0.76。大约980 cm（-1）处的光谱区域与测量到的结合钙浓度相关，总体PLS模型在预测浓度和测量浓度之间的相关系数（R2）为0.70。在大约980 cm（-1）处的相似光谱区域也与测量的缓冲峰面积相关，总体PLS模型在预测峰面积和测量峰面积之间的相关系数（R2）为0.64。结合Ca与缓冲峰面积之间的线性回归分析表明，结合Ca与缓冲峰面积相关（R2 = 0.73）。本研究表明，FTIR可以用于测量奶酪中的有机磷。它也有可能用于测量未稀释奶酪中的结合钙，并用于预测奶酪的缓冲能力。
The methods available for measuring organic P and bound Ca in cheese are either cumbersome or involve dilution of the cheese. Dilution of the cheese can lead to erroneous results, particularly in the case of bound Ca. Hence, the objective of this study was to evaluate the feasibility of Fourier transform infrared (FTIR) spectroscopy for direct measurement of organic P and bound Ca in Cheddar cheese. Two hundred sixteen samples of cheese were analyzed for protein-bound organic P, bound Ca using a water-extraction based method, and buffering curves. Additionally, the infrared spectra of the cheeses were collected between 4,000 and 650 cm(-1), at a resolution of 4 cm(-1), and 256 scans per sample. The spectral shifts in the infrared region from 1,050 to 900 cm(-1), in addition to the measured concentrations of organic P, bound Ca, and buffering peak area at pH 5.1, were used to develop calibration models using partial least squares (PLS) regression analysis. The spectral region of 956 to 946 cm(-1) correlated with the measured concentrations of organic P and the overall PLS model had a correlation (R2) of 0.76 between the predicted and measured concentrations. The spectral region at approximately 980 cm(-1) was correlated with the measured concentrations of bound Ca, and the overall PLS model had a correlation (R2) of 0.70 between the predicted and measured concentrations. A similar spectral region at approximately 980 cm(-1) was also correlated with the measured buffering peak areas and the overall PLS model had a correlation (R2) of 0.64 between the predicted and measured peak areas. A linear regression analysis between the bound Ca and buffering peak area demonstrated that bound Ca was correlated (R2 = 0.73) with buffering peak area. This study demonstrates that FTIR can be used to measure organic P in cheeses. It also has the potential to be used for measuring bound Ca in undiluted cheeses, and for prediction of the buffering capacity of cheese.