QUALITY CHANGES OF DONUTS AS INFLUENCED BY LEAVENING AGENT AND HYDROCOLLOID COATINGS ZAHRA SADAT ZOLFAGHARI, MOHEBBAT MOHEBBI 1 and MOHAMMAD HOSEIN HADDAD KHODAPARAST Department of Food Science and Technology, Ferdowsi University of Mashhad PO Box 91775-1163, Iran 1 Corresponding author. TEL: +98 511 8795618-29 (305); FAX: +98 511 8787430; EMAIL: Mohebbat2000@yahoo.com Accepted for Publication October 3, 2011 doi:10.1111/j.1745-4549.2011.00611.x ABSTRACT The effect of two edible coatings, methylcellulose (MC) and gum tragacanth (GT) in combination with two kinds of leavening agents, yeast and baking powder were examined on quality properties of donuts. Dough surface were coated with hydro- colloid solutions (1% w/w) then fried at 150C. GT and MC coatings significantly (P < 0.05) reduced oil uptake up to 33.00 and 24.74%, respectively. Fermented donuts had significantly lower oil content than cake donut, which is about 9.96%, while coating and leavening agent had no significant (P > 0.05) effect on moisture content of fried donuts. Crust color increased with frying time and density decreased during first minuets of frying time. Results of sensory evaluation showed there was no significant difference between coated and uncoated donuts. However, yeast- raised samples significantly (P < 0.05) had highest score on the appearance, porosity and uniformity of pores in comparison with cake donuts. PRACTICAL APPLICATIONS Donuts are typically sweet delectable snacks that represent the largest breakfast cat- egory in the in-store bakery because it is portable and easy-to-eat. However, the fat content of fried products may reach up to 50% of its total weight, and nowadays, more and more challenges about oil consumption and relevant diet problems can be seen, like excess weight and coronary heart disease. So it leads to increase research corresponding to produce fried food with lower oil content with the same quality. This article provides new information about oil reduction of fried donut and its quality properties. INTRODUCTION Deep-fat frying is a fast, convenient, energy-efficient cooking method in which water-containing foodstuff is immersed into frying oils at temperatures between 140 and 180C (Gertz 2000). Fried foods are very popular all around the world and comprise a wide variety of products (Brinkmann 2000). They are desirable because of their unique flavor and texture. However, the fat content of deep-fat fried products may reach up to 50% of its total weight (Pinthus et al. 1993; Funami et al. 1999). High consumption of lipids and oils may result in diet-related problems such as coronary heart disease and obesity. Being overweight is an independent risk factor for cardiovascular disease, diabetes mellitus or other common diseases (Mackay 2000). Thus, improving the frying process by controlling and lowering the final fat content of the fried products has been aimed by many studies (Ziaiifar et al. 2008). Some practical methods are based on: the modifica- tion of frying techniques, the frying medium and surface properties (Mellema 2003). Proper shaking and draining, exertion of optimum temperature and frying time (Mehta and Swinburn 2001; Mellema 2003), modification of viscosity and degradation of frying oil, and application of batters or coatings (Mellema 2003) are some alternatives. Use of hydro- colloids as coating is a method for reducing oil uptake in fried products because of their preventive properties. In addition, the oil-reduction effect of various gums, including hydrox- ypropyl methylcellulose (HPMC), guar gum, xanthan gum and gum Arabic, to batter formulation of chicken nuggets has been investigated and the results showed that HPMC and Journal of Food Processing and Preservation ISSN 1745-4549 1 Journal of Food Processing and Preservation •• (2012) ••–•• © 2012 Wiley Periodicals, Inc.