Simultaneous Determination of Instant Coffee, Plant Fat and Sugar Content in Liquid Coffee Beverage by Diffuse Reflectance Near-Infrared Spectroscopy

The diffuse reflectance near-infrared spectra of 20 liquid coffee beverage samples were collected by FT-NIR spectrometer combined with integral sphere in this thesis. The quantitative calibration models of instant coffee, plant fat and sugar were developed respectively. The result indicated that for the calibration models of instant coffee, plant fat and sugar, the dimensions of the calibration models are 4, 5 and 4 respectively; the determination coefficients (R² ) are 98.97%, 99.94% and 99.18% respectively; the root mean square errors of calibration (RMSEC) are 1.62, 0.42 and 1.58 respectively; the root mean square errors of cross validation (RMSECV) are 2.12, 0.72 and 2.01 respectively. The result of F-test showed that a very remarkable correlation exists between the estimated and specified values for each calibration model. This research indicated that NIR spectroscopy can be applied in the rapid, accurate and simultaneous determination of the three main ingredients in liquid coffee beverage. This research can provide some references for the quality control of liquid coffee beverage and the determination of the substance with chemical-fixation composition in liquid formula food.