CHICAGO—Vacuum frying can be an alternative to deep-fat frying to produce nutritious and novel snacks with desired quality attributes, since vitamins and color were greatly preserved and oil absorption could be substantially reduced, according to a study published in the Journal of Food Science.

Researchers in Chile sought to study the effect of oil temperature reduction when vacuum frying traditional (potatoes) and nontraditional products (carrots and apples) on most important quality attributes (vitamins, color and oil uptake).

Slices were fried using equivalent thermal driving forces, maintaining a constant difference between oil temperature and the boiling point of water at the working pressure. This resulted in frying temperatures of 160°C and 180°C, and 98°C and 118°C, for atmospheric and vacuum frying, respectively. Vacuum-fried carrot and potato chips absorbed about 50 percent less oil than atmospheric-fried chips, whereas vacuum-fried apple chips reduced oil absorption by 25 percent. Total carotenoids and ascorbic acid were greatly preserved during vacuum frying. Carrot chips vacuum fried at 98°C retained about 90 percent of total carotenoids, whereas potato and apple slices vacuum fried at 98°C, preserved around 95 percent of their initial ascorbic acid content. The findings showed the antioxidant capacity of chips may be related to both the presence of natural antioxidants and brown pigments developed at elevated temperatures.