Maryam Ajam - Young Researchers and Elite Club, Damghan Branch, Islamic Azad University, Damghan, Iran
Razieh Niazmand - Department of Food Chemistry, Research Institute of Food Science and Technology, Mashhad, Iran
Ashraf Gohari Ardabili - Department of Food Science and Technology, Bu-Ali Sina University, Hamedan, Iran

This study investigated the effect of carboxymethyl cellulose (CMC), saalab and tragacanth as coating agents, in two concentrations (0.3% and 0.7%) on oil absorption, acid value, peroxide value, microstructure, moisture content and sensory properties in doughnut cake during frying at 180±5°C. The results showed that coated doughnuts contained higher moisture and lower absorbed oil in comparison with uncoated ones (P<0.05). Increasing the coating concentration from 0.3% to 0.7% showed no significant differences in terms of moisture content (excluding tragacanth) as well as the amount of oil absorbed (P<0.05). Findings showed that samples treated with 0.7% tragacanth, had the most moisture content retention and the least oil absorbtion (34.24% oil uptake reduction). Coated doughnuts showed significant lower acid value (P<0.05) while there were no significant difference among CMC, saalab and tragacanth. Increasing coating concentration from 0.3% to 0.7% resulted in reduction of peroxide value (P<0.05). Photos taken with scanning electron microscope (SEM) showed that the uncoated sample surfaces were coarser and had more pores and larger cracks compared with sample coated with tragacanth and CMC. The total acceptability of coated doughnuts was higher than uncoated ones.

Deep frying, Doughnut, Hydrocolloid, Oil uptake