Near infrared spectroscopy : a potentially useful method for rapid determination of fat and protein content in homogenized diets

To investigate the potential of near-infrared reflectance (NIR) spectroscopy as a rapid and non-destructive method to determine total fat and protein in mixed, homogenized and freeze-dried human diets. 29 students collected duplicate portions of their diet for four consecutive days. In addition, a detailed food diary was kept. The duplicate portions were analysed for total protein and fat content both by traditional chemical analysis (Kjeldahl and Folch methods) and through the recently developed NIR spectroscopy method. In addition, traditional computerized estimation of nutrient composition was performed. Plotting of the NIR-predicted fat content against the chemically analysed fat content gave a correlation coefficient of 0. 99. Plotting of the NIR-predicted protein content against the Kjeldahl-analysed protein gave a correlation coefficient of 0.81. NIR-spectroscopy seems to be able to determine fat content in mixed, homogenized diets to a high degree of accuracy. In surveys involving duplicate portion sampling this will save time and money. The prediction accuracy for protein was less convincing, but acceptable depending on the need for accurate individual data. Norwegian Food Research Institute, Institute for Nutrition Research at the University of Oslo and the Research Society of the Norwegian Edible Fat Producers and the food company Mills DA. European Journal of Clinical Nutrition (2000) 54, 20-23