Analytical Methods Effect of different cooking methods on minerals, vitamins and nutritional quality indices of kutum roach (Rutilus frisii kutum) Hedayat Hosseini a , Maryam Mahmoudzadeh a , Masoud Rezaei b , Leila Mahmoudzadeh c , Ramin Khaksar a , Nader Karimian Khosroshahi d,⇑ , Aria Babakhani b a Department of Food Sciences and Technology, National Nutrition and Food Technology Research Institute, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran b Department of Seafood Science and Technology, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor, Iran c Faculty of Veterinary Medicine, Urmia University, Urmia, Iran d Deputy of Food and Drug, Tabriz University of Medical Sciences, Tabriz, Iran article info Article history: Received 22 December 2012 Received in revised form 14 September 2013 Accepted 1 October 2013 Available online 12 October 2013 Keywords: Cooking method Kutum roach Fatty acids Vitamins Minerals Nutritional quality indices abstract In this study, the influence of four cooking methods (baking, boiling, microwaving and frying) was evaluated on the nutritional value of kutum roach. Proximate, fatty acid composition, vitamin and mineral contents and also nutritional quality indices (NQI) of kutum roach were investigated before and after cooking treatment. All treated samples showed increase in protein, ash and lipid contents and decrease in the content of total omega-3 fatty acids (n-3) in comparison to raw fish fillets (control group). Cooking methods had no significant effect on omega-6 fatty acids (n-6) except for frying that increased it. Nonetheless, all of the cooking methods reduced vitamin B1, A and D contents. Boiling significantly decreased mineral contents including Na, K, P and Zn. Considering the overall nutritional quality indices, vitamin and mineral contents, baking is the best cooking method among other applied methods. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Kutum roach (Rutilus frisiikutum, family Cyprinidae) also known as ‘‘Kütüm’’ in Azerbaijani, ‘‘Caspian White Fish’’, ‘‘Caspian Roach’’, ‘‘Mahi-Sefid’’ in Persian, is the most popular fish in Iran with the highest economic value (Keyvan et al., 2008). Major changes occur in proximate, vitamins, mineral contents and the fatty acid composition of fish during cooking. One of the most important healthy aspects of fish consumption is due to the complex fatty acid profile. Major groups of fatty acids based on the number of double bonds include saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). Expert consultation recognised that individual fatty acids within each broad classification of fatty acids might have unique biological properties and health effects (FAO, 2010). It is evident that long-chain poly unsaturated fatty acids (LC-PUFAs) such as arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have markedly different physiological properties and biological functions compared to the shorter chain PUFAs such as linoleic acid and a-linolenic acid (Larsen, Eilertsen, & Elvevoll, 2011). Indeed, the polyunsaturated acids are more susceptible to oxidation during heating than their saturated analogues; however, several studies mentioned that EPA and DHA contents remained stable in some fish species in certain types of cooking. Due to different effects of fatty acids on health, it is necessary to define the nutritional quality index (NQI) with regard to the fatty acid profile and their biological functions. The nutritional quality index is estimated by several indices of fatty acid composition; the indices of atherogenicity (IA) and thrombogenicity (IT), according to Turan, Sonmez, and Kaya (2007), the hypocholesterolemic/hypercholesterolemic fatty acid ratio (HH) according to Testi, Bonaldo, Gatta, and Badiani (2006), EPA + DHA, PUFA/SFA-stearic acid according to Unusan (2007), PUFA/SFA ratio according to Kalogeropoulos, Andrikopoulos, and Hassapidou (2004) and Marques et al. (2010), n-3/n-6 PUFA ratios according to Marques et al. (2010), and ultimately ARA/EPA and UFA/SFA ratios according to Larsen et al. (2011). Fish is a potential source of vitamins and minerals and regardless of the distortion effects of cooking on nutrients, the cooking method may have an important role on the final content 0308-8146/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodchem.2013.10.012 ⇑ Corresponding author. Address: Deputy of Food and Drug, Tabriz University of Medical Sciences, Azadi St., Golgasht St., Tabriz, Iran. Tel.: +98 2122376426; fax: +98 2122360660. E-mail address: nader2006_kh@yahoo.com (N.K. Khosroshahi). Food Chemistry 148 (2014) 86–91 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem