Research note Using multi-slice-multi-echo images with NMR relaxometry to assess water and fat distribution in coated chicken nuggets Mecit Halil Oztop a, * , Harkirat Bansal b , Pawan Takhar b , Kathryn L. McCarthy c , Michael J. McCarthy c a Department of Food Engineering, Middle East Technical University, Ankara 06800, Turkey b Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States c Department of Food Science & Technology, University of California, Davis, One Shields Avenue, Davis, CA 95616, United States article info Article history: Received 12 June 2013 Received in revised form 11 October 2013 Accepted 19 October 2013 Keywords: Chicken nuggets Magnetic resonance imaging NMR relaxometry Water/fat content abstract Characterizing water and fat distributions in fried foods is of major importance in terms of taste and nutrition. The objective of this study was to introduce a new technique to quantify water and fat dis- tributions of chicken nuggets coated with methylcellulose (MC) through the use of magnetic resonance imaging (MRI) and NMR relaxometry. Multi-slice-multi-echo (MSME-Spin Echo based) images were performed on a 1.03 T spectrometer for the whole chicken nuggets to obtain relaxation time distribution of different regions (core and crust) of the nugget. MSME images provided the relaxation spectra of the core and crust separately and showed that relaxation times and relative areas of the proton pools in crust and core regions are correlated (mostly, R 2 > 0.85) with moisture and fat content. Results demonstrated that MSME images in combination with T 2 relaxometry are appropriate tools to quantify spatial water and fat distribution in various food products. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Deep-fat frying (DFF) can be defined as the process of drying and cooking through contact with hot oil (Sahin, Sastry, & Bayindirli, 1999). DFF is widely used in preparation of foods, because the consumers prefer the taste, appearance and texture of fried food (Rimac-Brncic, Lelas, Rade, & Simundic, 2004). Deep-fat fried products contain a substantial amount of fat. Oil absorption of the food is affected by many factors such as process conditions (tem- perature, time), pre-treatment of the food (such as dehydration methods, coating, etc.), and physico-chemical characteristics (Oztop, Sahin, & Sumnu, 2007). The trend of consuming low fat snack products is becoming popular. The food industry is continuously developing ways to manufacture low fat products while keeping the texture and other sensory characteristics at the desired level. Coating foods with hydrocolloids and modified starches (Akdeniz, Sahin, & Sumnu, 2005; Dogan, Sahin, & Sumnu, 2005a, 2005b); reducing the initial moisture content by air drying prior to frying (Pedreschi & Moyano, 2005) or osmotic dehydration before frying (Oztop et al., 2007) reduce the oil content of fried products significantly. Coating the surfaces of foods using batters in deep-fat frying is a common and popular process. The coating adds value to the product not only by controlling moisture loss and so oil uptake during frying, but also by providing nutrition, a crisp texture and the desired color to the fried products (Akdeniz et al., 2005; Dogan et al., 2005a). In order to understand the process of frying better, it becomes important to determine water and fat contents in foods and their distribution inside food material. It will also help us to understand the effectiveness of coating in reduction of oil uptake during frying. To determine water and fat content of the coating (crust) and the core (sample), usually analytical experiments are performed using gravimetric techniques for moisture content and soxhlet extraction for oil content. Magnetic resonance imaging is a non-destructive technique that could be used to determine water and oil/fat distribution in food products. MRI produces images based on proton distribution. Wa- ter- or oil-resolved MR images were reported for oil-in-water emulsions (Winkler, Mccarthy, & German, 1991) using the differ- ence in the relaxation time of oil and water (Poon, Szumowski, Plewes, Ashby, & Henkelman, 1989) for the capsicum seeds (Foucat, Chavagnat, & Renou, 1993), grape berries (Pope, 1993), cheese block (Ruan, Chang, Chen, Fulcher, & Bastian, 1998) and * Corresponding author. Tel.: þ90 3122105632; fax: þ90 3122102767. E-mail addresses: mecit@metu.edu.tr, mhoztop@gmail.com (M.H. Oztop). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.lwt.2013.10.031 LWT - Food Science and Technology 55 (2014) 690e694