The effect of air frying process on 3-monochloropropane-1,2-diol and glycidyl ester content of potatoes

Objective: The aim of the thesis is to optimize the conditions of the hot air frying process so that the amount of 3-monochloropropane-1,2-diol ester (3-MCPD-E) and glycidyl ester (G-E) in the fried product is minimum and to compare the fried potatoes produced under optimum conditions with conventional deep-fried potatoes. Materials and Methods: Potatoes were peeled, washed and cut into 8x8x60 mm slices. The potato slices were soaked in salt solutions of different concentrations (0-10%) for 30 min and the excess water was removed with a napkin. The potato slices were then thoroughly mixed with sunflower oil at different ratios (10-50 g oil/kg potato). Potato samples were fried in a hot air fryer at different temperatures (160-200°C) and times (7.5-25 min). The effects of process temperature, time, oil and salt content during frying of potato samples in hot air fryer were investigated by using Response Surface Methodology (RSM) and Central Composite Design (CCD). The oils of the fried potato samples were extracted in a rapid oil analyzer. The 3-MCPD-E and G-E contents of the oils extracted from the potato samples were determined. Potato samples fried in hot air and conventional deep fat under optimum conditions were compared in terms of 3-MCPD-E and G-E contents, moisture and oil content, color and sensory properties. Results: The minimum optimum process conditions for 3-MCPD-E and G-E were determined as 181.76°C temperature, 15.59 min time, 44.06 (g/kg) oil rate and 0.11 (%) salt rate. 3-MCPD-E content was detected at 0.35±0.05 mg/kg in hot-fried potatoes and 0.39±0.04 mg/kg in deep-fried potatoes. Similarly, the G-E contents of potatoes fried in hot air and deep oil were 0.03±0.00 mg/kg and 0.11±0.01 mg/kg, respectively. While linoleic acid is found to be 68.52% in the hot air frying process; it was found to be 68.64% in deep fat frying. In addition, 29.74 ppm α-tocopherol was found in air frying oil, while 6.45 ppm α-tocopherol was found in deep fat frying oil. The moisture content of potatoes fried in hot air was found to be 68.36%, the fat content was 5.10%, the L value was 56.81, the a value was 2.19 and the b value was 25.61. The moisture content of deep-fried potatoes was found to be 64.51%, the fat content was 7.72%, the L value was 49.85, the a value was 12.24 and the b value was 33.16. Sensory evaluation results revealed that deep frying received higher scores from the panelists. Conclusion: With this thesis study, the effect of hot air frying on the 3-MCPD-E and G-E content in the fried product was determined for the first time, and an optimization study was carried out for the first time to minimize the formation of these contaminants. Additionally, air frying and deep fat frying were compared for the first time in terms of 3-MCPD and G-E content. With this thesis study, safe french fries containing minimum levels of 3-MCPD-E and G-E was produced in an air fryer under controlled conditions.