Origin identification of dried distillers grains with solubles using attenuated total reflection Fourier transform mid-infrared spectroscopy after in situ oil extraction Ph. Vermeulen ⇑ , J.A. Fernández Pierna, O. Abbas, P. Dardenne, V. Baeten Valorisation of Agricultural Products Department, Walloon Agricultural Research Centre (CRA-W), Henseval Building, 24 Chaussée de Namur, 5030 Gembloux, Belgium article info Article history: Available online xxxx Keywords: DDGS Feed Authentication ATR-FT-MIR In situ extraction abstract The ban on using processed animal proteins in feedstuffs led the feed sector to look for other sources of protein. Dried distillers grains with solubles (DDGS) could be considered as an important source in this regard. They are imported into Europe mainly for livestock feed. Identifying their origin is essential when labelling is missing and for feed safety, particularly in a crisis situation resulting from contamination. This study investigated applying attenuated total reflection Fourier transform mid-infrared spectroscopy (ATR-FT-MIR) to the oil fraction extracted from samples in situ in order to identify the origin of DDGS. The use of spectroscopic and chemometric tools enabled the botanical and geographical origins of DDGS, as well as the industrial process used to produce them, to be identified. The models developed during the study provided a classification higher than 95% using an external validation set. Ó 2014 Published by Elsevier Ltd. 1. Introduction The ban on using processed animal proteins in feedstuffs led the feed sector to look for other sources of protein. Among the various possibilities, and apart from soybean meal (the main protein source in feed), it was thought that dried distillers grains with sol- ubles (DDGS) could be a source worth considering. As noted in Commission Regulation (EU) No. 575/2011, which deals with feed materials, dried distillers grains are the products of alcohol distil- lation, obtained by drying the solid residues of fermented grains (e.g., corn, wheat). DDGS are those grains to which syrup from the fermentation or evaporated spent wash has been added. The process involved in producing ethanol by fermenting yeasts from starch-containing plants is essentially the same as that for producing bioethanol and alcoholic beverages. The expansion of bioethanol production as a renewable energy source has led to increased availability of many co-products as livestock feed and greater variability in their composition. There are many reasons for the variability in DDGS composition, including differences in grain source (i.e., species, varieties) and composition, the process scheme and parameters, the amount of condensed solubles added to wet distiller grains, the effect of fermentation yeast, and analyt- ical methodologies (Liu, 2011). The first factor of variability is grain source. The starch used to produce ethanol comes mainly from 2 sources: corn and wheat (Cooper & Weber, 2012). Fermenting wheat concentrates the fat and protein content from about 2% to 6% and 13% to 38%, respec- tively. Fermenting corn concentrates the fat and protein content from about 4% to 11% and 9% to 26%, respectively (Beltranena & Zijlstra, 2008). The main differences between wheat and corn fat are explained by a higher rate of long fatty acid chain in corn (86% of C18) than in wheat (78% of C18) as well as a lower rate of saturated fatty acids in corn (12% of fatty acid total) than in wheat (18% of fatty acid total) and a higher rate of mono-unsatu- rated fatty acids in corn (28% of fatty acid total) than in wheat (15% of fatty acid total) (Morand-Fehr & Tran, 2001). Variety is also important. Some cereal breeding programs focus on breeding cul- tivars that will have a higher ethanol yield and improved DDGS composition. For example, the fat content of soft/hard, red/white and spring/winter wheat cultivars can differ significantly (Davis et al., 1980). The second factor of variability is the industrial process used to produce ethanol and co-products and the various ways of optimis- ing it. Processing methods used for raw grain can have a great impact on protein, fat, fibre and minerals rates and feeding charac- teristics. For example, the fractionation processes performed prior to fermentation are used to separate hulls/straw, germ and endo- sperm in order to produce co-products such as grain bran rich in fibre, grain germ rich in oil and distillers grains with high protein and low fat/fibre content. Another process that involves separating http://dx.doi.org/10.1016/j.foodchem.2014.09.103 0308-8146/Ó 2014 Published by Elsevier Ltd. ⇑ Corresponding author. Tel.: +32 81 62 03 87; fax: +32 81 62 03 88. E-mail address: p.vermeulen@cra.wallonie.be (Ph. Vermeulen). Food Chemistry xxx (2014) xxx–xxx Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Please cite this article in press as: Vermeulen, P., et al. Origin identification of dried distillers grains with solubles using attenuated total reflection Fourier transform mid-infrared spectroscopy after in situ oil extraction. Food Chemistry (2014), http://dx.doi.org/10.1016/j.foodchem.2014.09.103