The formation of potentially harmful compounds in churros, a Spanish fried-dough pastry, as influenced by deep frying conditions

Colour, moisture, hydroxymethylfurfural (HMF) and acrylamide (AA) were investigated in traditional Spanish churros. Samples were deep-fried in sunflower oil at lab-scale temperatures of 180, 190 and 200 °C and for frying times of 2, 3, 5 and 7 min. Fresh made churros were also obtained from local producers. HMF ranged from 1.2 ± 0.02 to 221.4 ± 2.02 mg/kg for lab-scale experiments and an average of 74.3 ± 47.5 mg/kg was recorded in commercial samples. AA ranged from below the limit of quantitation to 90 ± 0.6 μg/kg for lab-scale experiments and an average of 46 ± 24.5 μg/kg was measured in commercial samples. Temperatures between 185 and 200 °C are commonly used to obtain churros with an acceptable palatability and a crispy surface. However, HMF and AA levels increased nearly two-fold from 190 to 200 °C at the same frying times, indicating that a more precise control of frying temperatures is required to minimize their formation.