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A rapid Fourier Transform infrared (FTIR) spectroscopic method was developed to estimate caffeine in a variety of soft drinks and total methylxanthine content in tea and coffee using a single calibration model. FTIR spectrum of pure caffeine was characterized, and the 2 spectral regions of 1500 to 1800 cm -1 and 2800 to 3000 cm -1 were used for quantitative estimation using Partial least square (PLS) and principal component regression (PCR). FTIR spectroscopy with chemometrics using the PLS-First derivative spectra could predict the caffeine content accurately up to an R 2 value greater than 0.99 and a standard error of prediction (SEP) of less than 3.2 with 5 factors in the model.

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A Fourier transformed infrared (FTIR) spectroscopic method is described to estimate cholesterol after a single step extraction instead of the conventional colorimetric method. FTIR spectrum of pure cholesterol was characterized and the region between 2800 and 3200 cm−1 was used for quantitative estimation. Partial least square (PLS) and principal component regression (PCR) analysis were used for quantitative analysis. FTIR spectroscopy with chemometrics could predict the cholesterol content accurate to an r2 greater than 0.99 and a standard error of prediction (SEP) of less than 0.98. The developed model was successfully applied to predict cholesterol in commercial dairy products and validated with standard method and recovery studies. Results indicate that FTIR spectroscopy can determine the cholesterol content in dairy products in approximately 5 min.

A qualitative test for the detection of externally added urea (as synthetic milk) was developed using soybean urease. The quantitative detection of synthetic milk in dairy milk could be achieved by this method based on the ‘a’ value of ‘L, a, b’ scale of the HunterLab colorimeter and also by the diacetyl complexation method. Both methods are sensitive enough to detect amounts as low as 2% synthetic milk added to dairy milk, corresponding to 20 mg of added urea per 100 ml. This work reports on methods to detect and estimate unionic detergents, which are important ingredients of synthetic milk formulations, based on the extraction of a detergent—Methylcne Blue complex in chloroform which can be subsequently quantified by measuring the optical density at 653 nm. A base value of 0.52 for optical density was found to represent pure cow's milk Any result above this value suggested the presence of an anionic detergeni in milk.