Measurement of Central Temperature and Color Changes of Onion Slices During Frying Process

Subject Areas : Microbiology

F. Salehi ¹ (Assistant Professor of the Department of Biosystems Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran.)

Received: 2019-10-04 Accepted : 2019-10-04 Published : 2019-09-23

Keywords: Color, Frying, Kinetic, Onion, Surface Change,

Abstract :

Introduction: Frying is applied as one of the oldest methods of food preparation both in domestic and industrial scale. Color development during the frying process is a surface phenomenon that depends on the processing temperature and time. The aim of this research is the measurement of central temperature, surface changes and color changes the behavior of onion slices during frying process as a mathematical model at various temperatures. Materials and Methods: Onion slices with 1 cm thickness and cylindrical form were fried at the temperature of 150, 175 and 200 ºC and its central temperature was recorded using K type thermocouple with 1 mm thickness by 5-second intervals. The surface temperature of the product was measured using a laser thermometer. Color parameters as brightness (L*), redness (a*), yellowness (b*) and color change intensity (∆E) were recorded during frying time and kinetic model was fitted on their changes versus time and models coefficients were reported. Results: The temperature of the oil had a negative effect on the brightness of the fried onion and, with increasing process temperature, the brightness parameter decreased at the same time. The results of this experiment showed that most of the color changes occur in the early stages of the process. Higher temperatures increased the yellowness and redness of the onion surface from 14.24 to 29.31 and 5.73 to 17.86, respectively. Fried samples at a temperature of 200°C reduced the size about 40.48 %. The central temperature became closer to the water boiling point at a temperature of 200°C and after a brief period at this temperature, the temperature of the center increased again with full water exhaustion. Conclusion: The kinetics of the surface color parameters changes and color change intensity (∆E) of the onion followed the incremental exponential function and power function, respectively.

References:

Abbasi, S., Mousavi, S. &  Mohebbi, M., (2011). Mathematical modeling of onion drying process using hot air dryer. Iranian Food Science and Technology Research Journal, 6(3), 229-234.

Ahromrit, A. & Nema, P. K., (2010). Heat and mass transfer in deep-frying of pumpkin, sweet potato and taro. Journal of Food Science and Technology, 47(6), 632-637.

Baik, O. D. & Mittal, G. S., (2005). Heat and moisture transfer and shrinkage simulation of deep-fat tofu frying. Food Research International, 38(2), 183-191.

Bingol, G., Zhang, A., Pan, Z. & McHugh, T. H. (2012). Producing lower-calorie deep fat fried French fries using infrared dry-blanching as pretreatment. Food Chemistry, 132(2), 686-692.

Choe, E. & Min, D. (2007). Chemistry of deep‐fat frying oils. Journal of Food Science, 72(5).

Durán, M., Pedreschi, F., Moyano, P. & Troncoso, E. (2007). Oil partition in pre-treated potato slices during frying and cooling. Journal of Food Engineering, 81(1), 257-265.

Farkas, B. & Hubbard, L. (2000). Analysis of convective heat transfer during immersion frying. Drying Technology, 18(6), 1269-1285.

Farkas, B., Singh, R. & Rumsey, T. (1996). Modeling heat and mass transfer in immersion frying. II, model solution and verification. Journal of Food Engineering, 29(2), 227-248.

Ganjeh, M., Jafari, M., Ghanbari, F., Dezyani, M., Ezzati, R. & Soleimani, M., (2013). Modeling the drying kinetics of onion in a fluidized bed drier equipped with a moisture controller using regression, fuzzy logic and artificial neural networks methods. Iranian Journal of Nutrition Sciences & Food Technology, 7(5), 399-407.

Gökmen, V.  & Palazoğlu, T. K. (2008). Acrylamide formation in foods during thermal processing with a focus on frying. Food and Bioprocess Technology, 1(1), 35-42.

Khalilian, S., Ziaiifar, A., Asghari, A., Kashaninejad, M. & Mohebbi, M. (2017). Effect of cooking pretreatment on frying process of eggplant and evaluation of kinetic of oil absorption and moisture changes of eggplant during deep fat frying and cooling period. Journal of Food Science and Technology, 14, 147-154.

Krokida, M., Oreopoulou, V., Maroulis, Z. & Marinos-Kouris, D. (2001). Colour changes during deep fat frying. Journal of Food Engineering, 48(3), 219-225.

Michalak, J., Gujska, E. & Klepacka, J. (2011). The effect of domestic preparation of some potato products on acrylamide content. Plant Foods for Human Nutrition, 66(4), 307-312.

 

Moyano, P. C., Rı́oseco, V. K. & González, P. A. (2002). Kinetics of crust color changes during deep-fat frying of impregnated French fries. Journal of Food Engineering, 54(3), 249-255.

Pedreschi, F., Moyano, P., Kaack, K. & Granby, K. (2005). Color changes and acrylamide formation in fried potato slices. Food Research International, 38(1), 1-9.

Rodriguez-Saona, L. E. & Wrolstad, R. E. (1997). Influence of potato composition on chip color quality. American Journal of Potato Research, 74(2), 87-106.

Romani, S., Bacchiocca, M., Rocculi, P. & Dalla Rosa, M. (2009). Influence of frying conditions on acrylamide content and other quality characteristics of French fries. Journal of Food Composition and Analysis 22(6), 582-588.

Sabbaghi, H., Ziaiifar, A., Sadeghi, M.A., Kashaninejad, M. & Mirzaei, H. (2017). Kinetic modeling of color changes in french fries during frying process. Journal of Food Technology and Nutrition, 14(1), 65-76.

Sahin, S., Sastry, S. & Bayindirli, L. (1999). Heat transfer during frying of potato slices. LWT-Food Science and Technology, 32(1), 19-24.

Salehi, F. (2017). Rheological and physical properties and quality of the new formulation of apple cake with wild sage seed gum (Salvia macrosiphon). Journal of Food Measurement and Characterization, 11(4), 2006-2012.

Salehi, F. (2018). Color changes kinetics during deep fat frying of carrot slice. Heat and Mass Transfer, 54(11), 3421-3426.

Salehi, F. (2019). Color changes kinetics during deep fat frying of kohlrabi (Brassica oleracea var. gongylodes) slice. International Journal of Food Properties, 22(1), 511-519.

Salehi, F. & Amin Ekhlas, S. (2018). The effects of wild sage seed gum (Salvia macrosiphon) on the rheological properties of batter and quality of sponge cakes. Journal of Food Biosciences and Technology, 8(2), 41-48.