Effect of Moisture Uptake on the Repeatability of near Infrared Spectroscopy Analyses of Ewe Milk Using the Dry Extract System for Infrared (DESIR) Method

Abstract

This paper reports a study carried out to determine the effect of post-filter-drying moisture uptake on the repeatability of NIR spectroscopy analyses of ewe milk using the dry-extract system for infrared (DESIR). The study assessed the spectral repeatability of the method and the effect of moisture uptake on that repeatability, using graphical representations and root mean squared (RMS) error between spectra, as well as multivariate Mahalanobis distances (GH values) and predicted constituent values (protein, fat and dry matter). The spectral repeatability of this method of dried milk analysis using glass-fibre filters was very high, both spectrally per se [RMS MEAN = 3.914 µlog (1/R) and STD = 4.126 µlog (1/R)] and in terms of NIR spectroscopy prediction of chemical components and of the Mahalanobis distance.Using a single filter per milk sample is thus considered sufficient to guarantee the required accuracy and precision of the DESIR method.Differences between spectra due to the presence or absence of air exposure [STD = 6446 µlog (1/R)] were greater than the method repeatability error. Predictions of protein, fat and dry matter were significantly higher for air-exposed filters, due to moisture uptake; the increase in GH values for air-exposed filters was highly significant, suggesting that milk samples to be analysed using the DESIR method should be stored in a desiccator after drying and before NIR analysis and not left exposed to air.

Measurement of pesticide residues in peppers by near‐infrared reflectance spectroscopy

“…These authors showed that the DESIR technique was able to measure sugar content in juice at concentrations ranging from 0.0 to 5.0%. These excellent results encouraged other researchers to use the technique for the quantitative analysis of milk,17–19 beer,20 wine,21 tea,22 and orange juice,23 and for the measurement of trace pesticide residues 24, 25…”

Fat color and reflectance spectra to evaluate the β-carotene, lutein and α-tocopherol in the plasma of bovines finished on meadows or on a dry total mixed ration

“…The acquisition of the spectrum was made according to the method described by Núñez-Sánchez et al (2008), which is based on the DESIR method (Meurens et al, 1987) using a glass fiber filter (AP40 047, Millipore Corporation, Billerica, MA, USA). Filters were inserted into a cylindrical cup with a quartz glass having an internal diameter of 35 mm and a depth of 10 mm.…”

“…It has been used to accurately determine several carotenoid contents in maize and Chinese kale (Brenna and Berardo, 2004) and to determine the ␣-tocopherol content in unground commercial feeds. However, when the substance of interest is contained in an aqueous matrix, NIRS calibrations fail because the near infrared (NIR) absorption of water is strong (Blanco and Peguero, 2007) and greater than that of the solutes (Núñez-Sánchez et al, 2008). Consequently, removing water from materials before NIRS analysis could improve the quantification of certain substances, for which a Dry-Extract System for Infra Red (DESIR) was developed (Meurens et al, 1987) to avoid the influence of water NIR absorption.…”

“…Consequently, removing water from materials before NIRS analysis could improve the quantification of certain substances, for which a Dry-Extract System for Infra Red (DESIR) was developed (Meurens et al, 1987) to avoid the influence of water NIR absorption. DESIR has been used successfully to determine the composition of milk (Núñez-Sánchez et al, 2008;Coppa et al, 2010) and perform pregnancy tests using the plasma of ewes (Andueza et al, 2014).…”

Prediction efficiency by near-infrared spectroscopy of immunoglobulin G in liquid and dried bovine colostrum samples

“…Regarding milk quality, DESIR was successfully used with goat's milk to calibrate NIRS equations for milk components, i.e., total protein, total casein, α s-, β - and κ -caseins, fat and lactose (Díaz-Carrillo et al 1993). Spectra from dried ewe's milk samples were also collected to determine total protein, total casein, fat, total solids, and somatic cell count (Núñez-Sánchez et al 2002). Since NIRS is a reliable method to predict IgG content in bovine colostrum, and taking into account that dried samples could improve prediction equations, DESIR method was tested to improve the accuracy of prediction of colostrum IgG by NIRS over results obtained by transflectance on liquid samples.…”