As one of the staple crops, the safety of wheat flour will be very important to the customers' health. Short-wavelength near-infrared spectroscopy combined with partial least square algorithm is applied in this research to develop the calibration models of calcium oxide, calcium hydroxide
and the total content, which are validated by the external validation set. The result indicated that the characteristic absorption of calcium oxide and calcium hydroxide exists at 10373 cm−1; the determination coefficients (R2) of calcium oxide, calcium hydroxide
and the total content are 95.16%, 99.04% and 99.22% respectively; the root mean square errors of calibration (RMSEC) are 0.49 0.27 and 0.39 respectively, the root mean square errors of cross validation (RMSECV) are 0.66, 0.52 and 0.64 respectively, the detection limits of this
method for calcium oxide, calcium hydroxide and the total content are 1.47%, 0.81% and 1.17% respectively; the root mean square errors of prediction (RMSEP) are 1.34, 0.49 and 1.50 respectively; the ratio performance deviations (RPD) are 2.19, 7.26 and 3.53 respectively; the
correlation coefficients of the regression equations of external validation are 0.9823, 0.9917 and 0.9611 respectively. The result of F-test indicated that a very remarkable correlation exists between the estimated and specified values of both the calibration sets and the external validation
sets. The calibration models are precise enough to adapt to the on-site determination of the lime in wheat flour rapidly. This research, to some extent, will provide some reference for the quality control and rapid inspection of the wheat flour, which is of great importance to the quality
monitoring of wheat flour, the guarantee of customers' health and the development of SW-NIR spectrometer for determining lime or other banned additives in wheat flour.
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