Optimisation of hot-air frying conditions to minimise 3-MCPD and glycidyl esters in French fries: comparison with deep-fat frying

This study aimed to optimise hot-air frying conditions to minimise the formation of 3-monochloropropane-1,2-diol esters (3-MCPD-E) and glycidyl esters (G-E) in French fries and to compare the optimised samples with deep-fat-fried counterparts. The effects of temperature (160-200 °C), time (7.5-25 min), added oil level (10-50 g/kg), and added salt level (0-10%) were evaluated using Response Surface Methodology (RSM). The optimal conditions were determined as 181.8 °C, 15.6 min, 44.1 g/kg added oil, and 0.11% added salt, with good agreement between predicted and experimental values. Under these conditions, 3-MCPD-E and G-E levels were slightly lower in hot-air fried samples (0.35 and 0.03 mg/kg, respectively) than in deep-fat-fried samples (0.39 and 0.11 mg/kg). Hot-air frying also resulted in lower oil content (5.1% vs. 7.7%) and higher moisture content, while deep-fat-fried samples showed generally higher sensory scores. These results indicate that optimised hot-air frying can reduce process-induced contaminants and oil uptake, although some oxidative changes may occur. Hot-air frying can therefore be considered a suitable alternative to deep-fat frying for producing fried potato products with improved safety and acceptable quality.