RESUMO
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⯵g/mL to 5.44⯵g/mL (approximately 70%) when exposed to 180⯰C. Photodegradation of unencapsulated folic acid lowered its concentration from 17.17⯵g/mL to 12.58⯵g/mL (~26% of reduction), when exposed for 1â¯h to UVA irradiation. However, folic acid concentration when encapsulated in fibers (1.5%) was maintained or only slightly reduced from 9.73⯵g/mg to 8.88⯵g/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⯵g/mg to 7.88⯵g/mg when exposed to 24â¯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.
Assuntos
Ácido Fólico , Nanocápsulas/química , Zeína/química , Estabilidade de Medicamentos , Técnicas Eletroquímicas , Ácido Fólico/análise , Ácido Fólico/química , Ácido Fólico/efeitos da radiação , Nanocápsulas/efeitos da radiação , Fotólise , Polímeros , Temperatura , Raios Ultravioleta , Zeína/efeitos da radiaçãoRESUMO
This study attempts to examine the folic acid stability after irradiation treatment, under different physical states, pH values, and atmosphere conditions. Aqueous folic acid samples, folic acid in powder, and wheat flour fortified with folic acid were irradiated by an electron beam (E-beam) between 0 (control) and 10.0 kGy. It was realized that the physical state of folic acid plays an important role on its stability toward E-beam processing, being largely unstable in solution, no matter the pH and atmosphere conditions assayed. Otherwise, folic acid in powder showed huge irradiation stability, even when mixed in a dry food matrix, such as fortified wheat flour samples.
Assuntos
Ácido Fólico/efeitos da radiação , Irradiação de Alimentos/efeitos adversos , Estabilidade de Medicamentos , Farinha/análise , Ácido Fólico/química , Alimentos Fortificados/análise , Concentração de Íons de Hidrogênio , Soluções , ÁguaRESUMO
Folic acid, or pteroyl-l-glutamic acid (PteGlu), is a precursor of coenzymes involved in the metabolism of nucleotides and amino acids. PteGlu is composed of three moieties: a 6-methylpterin (Mep) residue, a p-aminobenzoic acid (PABA) residue, and a glutamic acid (Glu) residue. Accumulated evidence indicates that photolysis of PteGlu leads to increased risk of several pathologies. Thus, a study of PteGlu photodegradation can have significant ramifications. When an air-equilibrated aqueous solution of PteGlu is exposed to UV-A radiation, the rate of the degradation increases with irradiation time. The mechanism involved in this "auto-photo-catalytic" effect was investigated in aqueous solutions using a variety of tools. Whereas PteGlu is photostable under anaerobic conditions, it is converted into 6-formylpterin (Fop) and p-aminobenzoyl-l-glutamic acid (PABA-Glu) in the presence of oxygen. As the reaction proceeds and enough Fop accumulates in the solution, a photosensitized electron-transfer process starts, where Fop photoinduces the oxidation of PteGlu to Fop, and H(2)O(2) is formed. This process also takes place with other pterins as photosensitizers. The results are discussed with the context of previous mechanisms for processes photosensitized by pterins, and their biological implications are evaluated.