scholarly journals Influence of Diffuse Reflectance Measurement Accuracy on Scattering Coefficient in Determination of Optical Property with Integrating Sphere Optics

2014 ◽  
Vol 35 (2) ◽  
pp. 158-164
Author(s):  
Takuro Horibe ◽  
Katsunori Ishii ◽  
Daichi Fukutomi ◽  
Kunio Awazu
2017 ◽  
Vol 100 (2) ◽  
pp. 499-502 ◽  
Author(s):  
Lukáš Dvořák ◽  
Martin Fajman ◽  
Kvetoslava Sustova

Abstract This study monitored the influence of milk samples temperature on the measuring accuracy of FT-NIR spectroscopy in milk content analysis. Reference methods were used to determine dry matter, fat, protein, and lactose content in cow's milk. Milk samples were measured in reflectance mode on an integrating sphere with the use ofa compression cuvette and a transflectance cuvette, ensuring a beam trajectory length of h = 0.2 mm. The samples were measured at 18, 20, 22, 24, and 40°C, and analyses were performed at 100 scansat a resolution of 8 cm−1. The measurements were influenced by the temperatures of the samples during the evaluation of all analyzed constituents (P < 0.05). Our results confirmed that the accurate determination of milk constituents requires maintaining, during analysis, the temperature conditions of the samples and the conditions for which the spectrophotometer calibration was designed.


2016 ◽  
Vol 71 (5) ◽  
pp. 951-962 ◽  
Author(s):  
Sabrina Stocker ◽  
Florian Foschum ◽  
Philipp Krauter ◽  
Florian Bergmann ◽  
Ansgar Hohmann ◽  
...  

Dairy products play an important role in our daily nutrition. As a turbid scattering medium with different kinds of particles and droplets, each alteration of these components changes the scattering properties of milk. The goal of this work is the determination of the amount of main scattering components, the fat droplets and the casein micelles, by understanding the light propagation in homogenized milk and in raw milk. To provide the absolute impact of these milk components, the geometrical and optical properties such as the size distribution and the refractive index (RI) of the components have to be examined. We determined the reduced scattering coefficient [Formula: see text] and the absorption coefficient [Formula: see text] from integrating sphere measurements. By use of a collimated transmission setup, the scattering coefficient [Formula: see text] was measured. Size measurements were performed to validate the influence of the fat droplet size on the results of the scattering properties; also, the RI of both components was determined by the said coefficients. These results were used to determine the absolute impact of the milk components on the scattering behavior. By fitting Mie theory calculations on scattering spectra [Formula: see text] and [Formula: see text] from different raw milk samples, it was possible to get reliable values for the concentrations of fat and casein and for the size of the fat droplets. By destroying the casein micelles, it was possible to separate the influence of the different scattering components on scattering behavior.


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