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

Objective: To investigate the potential of near-infrared reflectance (NIR) spectroscopy as a rapid and nondestructive method to determine total fat an d protein in mixed. homogenized and freeze-dried human diets. Design: 29 students collected duplicate porions of their diet fur four cons ecutive days. In addition, a detailed food diary was kept. The duplicate po rtions were analysed for total protein and fat content both by traditional chemical analysis (Kjeldahl and Folch methods) and through the recently dev eloped NIR spectroscopy method. In addition, traditional computerized estim ation of nutrient composition was performed. Results: Plotting of the NIR-predicted fat content against the chemically a nalysed fat content gave a cell-elation coefficient of 0.99. Plotting of th e NIR-predicted protein content against the Kjeldahl-analysed protein gave a correlation coefficient of 0.81. Conclusion: NIR-spectroscopy seems to be able to determine fat content in m ixed. homogenized diets to a high degree of accuracy. In surveys involving duplicate portion sampling this will same time and money. The prediction ac curacy for protein was less convincing, but acceptable depending on the nee d for accurate individual data.