Thermal and irradiation resistance of folic acid encapsulated in zein ultrafine fibers or nanocapsules produced by electrospinning and electrospraying.

The objectives of this study were to characterize zein fibers and capsules prepared by electrospinning and electrospraying techniques, respectively, and then use them to encapsulate folic acid. Folic acid containing fibers and capsules (0.5, 1.0, and 1.5%, w/v) were submitted to thermal treatment (100, 140, and 180 °C) and ultraviolet A light (UVA) irradiation to evaluate the resistance of folic acid. Zein fibers and capsules containing folic acid showed high encapsulation efficiency (>80%). Unencapsulated folic acid showed a reduction in folic acid content from 17.17 μg/mL to 5.44 μg/mL (approximately 70%) when exposed to 180 °C. Photodegradation of unencapsulated folic acid lowered its concentration from 17.17 μg/mL to 12.58 μg/mL (~26% of reduction), when exposed for 1 h to UVA irradiation. However, folic acid concentration when encapsulated in fibers (1.5%) was maintained or only slightly reduced from 9.73 μg/mg to 8.88 μg/mg after thermal treatment at 180 °C. The capsules containing 1.5% of folic acid also presented a slight reduction in folic acid concentration from 8.84 μg/mg to 7.88 μg/mg when exposed to 24 h of UVA irradiation. Zein fibers and capsules containing folic acid present promising characteristics for application in foods that require thermal processing or exposure to irradiation.