ConclusionIn this paper, we discussed the influence that FD, SD, MSC and VNpre-processing methods has on the PLS-NIR calibration modelingfor the FT-NIR spectroscopy analysis IV and FFA content of animalfat wastes and their blends. More robust calibrations were obtainedby using real production samples, and variability in the sample dataset can be introduced by blending animal fat feedstocks directly inthe biodiesel production reactor. The results show that FT-NIR iscapable of providing a rapid and accurate measurement of IV andFFA of animal fats and their blends destined for biodiesel produc-tion with a proper calibration and a responsive model. Once thecalibrations are in place, FT-NIR is a fast and easy to use methodfor the IV and FFA content measurement in a biodiesel productionenvironment. It drastically reduces the time from routine biodieselfeedstock quality control analysis and does not involve the use ofany chemical reagents. FD pre-processing method was found to givea robust and reliable calibration model for both IV and FFA mea-surement. Conclusively, using FT-NIR spectroscopy as a biodieselfeedstock (animal fat wastes and blends) quality control tool for IVand FFA measurement will reduce cost of production and possiblechemical hazard in the production environment.