Nutrient Degradation in Baked or Air-Fried Sweet Potato Chips

Abstract

Objectives

The project tested the hypothesis that baked sweet potato chips will retain nutrients and can be produced with lower fat than commercially prepared fried chips.

Sweet potato is a staple food that is a good source of dietary fiber, copper, manganese, antioxidants, vitamins C, A, B6, and E and is low in calories and fat. Orange-fleshed sweet potato is a good source of beta-carotene, a vitamin A precursor. Due to its nutritional benefits, demand is increasing and a growing market has created a variety of sweet potato products. Beta-carotene is a heat, light, oxygen labile molecule that can be used as a marker for nutrient degradation when sweet potato is heat-processed. Most commercial sweet potato chips are fried in oil, which helps to lower the glycemic index, but may also lower the nutrient density in the higher calorie product. Our goal is to test newer methods for making baked sweet potato chips with commercially available air-fryers and compare the products to chips baked with conventional and convection ovens.

Methods

Sweet potato chips were prepared from fresh commercially purchased Covington sweet potatoes cut into 3 mm slices with a semi-automatic food slicer. The slices were lightly sprayed with a vegetable oil aerosol and cooked in air fryers for 15 min at 400°F (204°C), in convection ovens for 15 minutes at 415°F (213°C), and in conventional oven at 400°F for 20 minutes. Crispness was determined by a 3-point bending test.

Results

The fresh sweet potato contained 22% DM and the chips averaged 70% DM after cooking in air fryers, 60% DM after cooking in convection ovens, and 64% DM after cooking in conventional oven. Beta-carotene content was 24.2 ± 4.5 mg/100 g DM in the fresh sweet potato, and decreased to an average 7.6 ± 1.9 mg/100 g DM in the air-fried chips, 14.1 ± 4.1 mg/100 g DM in the chips cooked in the convection ovens, and 6 ± 1.7 mg/100 g DM in the conventional oven. The rheological test found the chips with greater beta-carotene retention from the convection oven to be less crisp and have less charring than chips made in the air fryer or in the conventional oven.

Conclusions

Air frying technology shows promise for making low-fat sweet potato chips but nutrient degradation may still be an issue that needs further research.

Funding Sources

NC Agricultural Foundation.