Determination of advanced glycation endproducts in cooked meat products Gengjun Chen, J. Scott Smith ⇑ Animal Sciences and Industry, Kansas State University, 208 Call Hall, Manhattan, KS 66506, United States article info Article history: Received 28 January 2014 Received in revised form 14 May 2014 Accepted 20 June 2014 Available online 8 July 2014 Keywords: Advanced glycation endproducts Ne-carboxymethyllysine Cooked meat abstract Advanced glycation endproducts (AGEs), a pathogenic factor implicated in diabetes and other chronic dis- eases, are produced in cooked meat products. The objective of this study was to determine the AGE con- tent, as measured by Ne-carboxymethyllysine (CML) levels, in cooked chicken, pork, beef and fish (salmon and tilapia) prepared by three common cooking methods used by U.S. consumers: frying, baking, and broiling. The CML was detected in all the cooked samples, but the levels were dependent on types of meat, cooking conditions, and the final internal temperature. Broiling and frying at higher cooking tem- perature produced higher levels of CML, and broiled beef contained the highest CML content (21.8 lg/g). Baked salmon (8.6 lg/g) and baked tilapia (9.7 lg/g) contained less CML as compared to the other muscle food samples. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Advanced glycation endproducts (AGEs) are a group of complex and heterogeneous compounds that are formed through the Mail- lard reaction, a nonenzymatic reaction between reducing sugars and free amino groups (Ahmed, 2005). Although the mechanism of the Maillard reaction is still not fully known, the AGEs exist in the body as well as in food. The common AGEs found in food are Ne-carboxymethyl lysine (CML), methylglyoxal-lysine dimers (MOLD), pentosidine and pyrraline (Wu, Huang, Lin, & Yen, 2011). Current research suggests excessive consumption of these compounds may contribute to metabolic chronic diseases includ- ing diabetes, renal disorders, and Alzheimer’s disease (Brownlee, 1994; Kim, Reddy, Rahbar, Lanting, & Natarajan, 2002; Koschinsk et al., 1997). Some epidemiological studies have shown that con- sumption of certain dietary AGEs are indicators of oxidative stress and inflammation such as 8-isoprostanes, which may play an important role in disease pathologies (Uribarri et al., 2007). More- over, reductions of inflammatory mediators were also found in dia- betic subjects by restricting their dietary AGEs (Vlassara et al., 2002). Based on some animal studies, AGE-rich diets fed to mice was associated with kidney disease and accumulation of AGEs in tissue (Hofmann et al., 2002; Vitek et al., 1994). Thus, information on the levels of dietary AGEs and the prevalence of these com- pounds in food items is desirable. It is established that the diet is a significant source of exogenous AGEs. In addition, long-term storage and cooking procedures can increase AGEs content in foods (Forster & Henle, 2003). The con- centrations and types of AGEs in cooked meat depend on several factors including cooking method, cooking temperature and time, and the presence of protein and fat (Goldberg et al., 2004). Tradi- tional cooking methods may play a key role in AGEs consumption and exposure. Compared to some Asian countries, it is estimated that broiling or grilling was used more to cook steak (34%), and pan frying was used more to cook chicken (56%) and fish (54%) in the U.S. (Keating & Bogen, 2004). All of these cooking methods have been reported to induce AGE formation (Ames, 2008; Delgado-Andrade, Seiquer, Pilar, & Morales, 2007). For example, Goldberg et al. (2004) found that higher levels of CML in meats cooked by broiling and frying with higher temperatures. Although some previous studies have investigated AGEs levels in food (Dittrich et al., 2006; Drusch, Faist, & Erbersdobler, 1999; Goldberg et al., 2004; Hull, Woodside, Ames, & Cuskelly, 2012), direct comparison is of results is difficult because of the various preparation methods, meat types, and cooking conditions. For instance, meat samples have been cooked to different internal tem- peratures in past studies, which yielded inconsistent results. Therefore information on AGEs levels should include some stan- dard parameters such as the internal temperature of the cooked samples. CML has been studied extensively as an oxidation product, and is reported to be formed by numerous pathways in food systems (Ahmed, Thorpe, & Baynes, 1986). In the process of cooking meat http://dx.doi.org/10.1016/j.foodchem.2014.06.081 0308-8146/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +1 7855321219; fax: +1 7855325681. E-mail address: jsschem@ksu.edu (J. Scott Smith). Food Chemistry 168 (2015) 190–195 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem