بهبود شرايط فرآيند سرخ كردن حلقه هاي پياز به منظور توليد محصول با كيفيت مطلوب

چكيده انگليسي :

Improvement of Processing Condition of Fried Onion Rings In order to Produce High Quality Product Zohreh Hajihashemi z hajihashemi@ag iut ac ir January 26 2010 Department of Agriculture Food Science and Technology Group Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiMohammad Shahedi shahedim@cc iut ac ir and Mehdi Kadivar mak120@mail usask ca Abstract Deep fat fried onions are used widely as an appetizer in different food products Quality of whole fried foodsdepends on oil quantity and quality water content and their color characteristics Differences in dry mattercontent of onions from different growers or different varieties can be regulated or even eliminated by pre frydrying of onions It is recommended using a pre fry drying process for increasing quality of fried onions Moreover recently researchers showed using hydrocolloids as a coating agent can reduce oil uptakes and alsoprovide more sensory acceptability for consumers This treatment can also improve color appearance and flavorof fried products In this research effect of pre fry drying and coating on fried onions were investigated in orderto improve its organoleptic and sensory characteristics storage quality and decreasing oil absorption of onionrings Two local varieties of onions Yellow Sweet Spanish and Red Dorcheh were purchased from localgrowers Physico chemical properties of samples such as dry matter and nitrate were measured according tostandard methods In addition reducing sugar contents of the samples were measured by High PerformanceLiquid Chromatography HPLC Samples were cut using a laboratory slicer in order to achieve a uniform ringsin terms of size and shape The onion rings were dried at 60 C to achieve final dry matter of 20 and 30 WB The samples without drying 20 and 30 dry matter were then fried at 170 C for 300 240 and 150 secondsdepending on dry matter of samples Onion rings were coated by gelatinized starch solutions 4 and 5 andCarboxymethyl Celluloses solutions 0 5 and 1 for 5 seconds at 37 C Coated onion rings were also fried at170 C for 150 second Fried samples were then stored under nitrogen atmosphere at ambient temperature andnormal atmosphere at ambient and 18 C for 3 months in polyethylene packages Oil content peroxide value PV tiobarbitoric acid index TBA color and sensory characteristics of fried samples were measured just uponfrying every month up to 3 months storage Result indicates that increasing of drying time had negative effect onsamples color and samples were darker comparing by those with lower dry matter In addition drying ofsamples to 20 dry matter had not significant effect on PV and TBA whereas samples were dried to 30 drymatter had significant difference on these parameters Results have also indicated that pre fry drying had a bettersensory quality especially on Yellow Sweet Spanish cultivar with 30 dry matter therefore this condition waschosen as best treatment and in the next step this sample was coated by hydrocolloids Onion rings that had beencoated by 1 CMC solution and fried at 170 C for 150 seconds absorbed less oil in compare to otherstreatments This sample was stored for 3 months and result shows that their PV and TBA were significantlylower than those of without coating Key words Fried onion rings Pre drying Coating Oil uptake

حاجي هاشمي، زهره

بهبود شرايط فرآيند سرخ كردن حلقه هاي پياز به منظور توليد محصول با كيفيت مطلوب

خشك كردن , پوشش دهي , جذب روغن