January 2000, Volume 54, Issue 1, Pages 20 - 23

Original Communication

Near infrared spectroscopy--a potentially useful method for rapid determination of fat and protein content in homogenized diets K Almendingen1, HM Meltzer1,2, JI Pedersen1,3, BN Nilsen4 & M Ellekjær4 1Institute for Nutrition Research, Faculty of Medicine, University of Oslo, Blindern, Oslo, Norway     2Department of Environmental Medicine, National Institute of Public Health, Torshov, Oslo, Norway     3Akershus College, Bekkestua, Norway     4Norwegian Food Research Institute, Ås, Norway     Correspondence to: HM Meltzer , National Institute of Public Health, PO Box 4404 Torshov, N-0403 Oslo, Norway.     Guarantor: HM Meltzer. Contributors: KA had the idea for the study, was responsible for the collaboration with industry and wrote the first version of the manuscript. HMM provided duplicate portion samples for the study, and wrote the final versions of the manuscript. JIP supervised Almendingen and Meltzer, and commented on the manuscript. BNN performed the NIR analysis and commented on the manuscript. MRE was responsible for the NIR analysis, part of the statistical analysis, and wrote selected parts of the manuscript.

Keywords

NIR spectroscopy;   duplicate portions;   protein analysis;   fat analysis;   dietary survey

Abstract

Objective: 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. Design: 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. Results: 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. Conclusion: 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. Sponsorship: 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

Received 18 March 1999; Revised 30 June 1999; Accepted 16 July 1999

^© Macmillan Publishers Ltd 2000