Milk Fat Analysis by Fiber-optic Spectroscopy

Ohtani, S.; Wang, T.; Nishimura, K.; Irie, M.

doi:2005.18.4.580

Article

Animal Breeding and Genetics

Asian-Australasian Journal of Animal Sciences 2005;18(4): 580-583.
https://doi.org/10.5713/ajas.2005.580 Published online April 20, 2005.

Milk Fat Analysis by Fiber-optic Spectroscopy

S. Ohtani, T. Wang, K. Nishimura, M. Irie

Abstract

We have evaluated the application of spectroscopy using an insertion-type fiber-optic probe and a sensor at wavelengths from 400 to 1,100 nm to the measurement of milk fat content on dairy farms. The internal reflectance ratios of 183 milk samples were determined with a fiber-optic spectrophotometer at 5째C, 20째C and 40째C. Partial least squares (PLS) regression was used to develop calibration models for the milk fat. The best accuracy of determination was found for an equation that was obtained using smoothed internal reflectance data and three PLS factors at 20째C. The correlation coefficients between predicted and reference milk fat at 5째C, 20째C and 40째C were r=0.753, r=0.796 and r=0.783, respectively. The predictive explained variances (Q2) of the final model, moreover, were more than 0.550 at all temperatures, and the regression coefficients of determination (R2) were more than 0.6 (60%). Our results indicate that milk has different internal reflectance measured in the range of visible and near infrared wavelengths (400 to 1,100 nm), depending on its fat content.

Keywords: Cow; Fiber-optic Spectroscopy; Milk Fat