title: Photoprotection of vitamins in skimmed milk by an aqueous soluble lycopene-gum Arabic microcapsule.
abstract: Riboflavin (Rf)-mediated photosensitized degradation of vitamins A and D3 in skimmed milk under illumination with a white fluorescence lamp was studied by using the HPLC technique. The photosensitized degradation of both vitamins followed first-order kinetics, and the temperature effect on the observed photodegradation rate constant allowed the determination of the activation energy Ea as being 4 and 16 kcal/mol for vitamins A and D3, respectively. The addition of lycopene microencapsulated by spray-drying with a gum arabic-sucrose (8:2) mixture (MIC) produced a reduction of ca. 45% in the photosensitized degradation rate of both vitamins. Front-face fluorescence experiments showed the same photoprotection factor in the degradation of Rf itself, indicating that the photodegradation mechanism involved Rf-mediated reactive species, such as the excited triplet state of Rf, 3Rf*, and/or singlet molecular oxygen, 1O2. The interaction of both 3Rf* and 1O2 with MIC was evaluated in aqueous solutions by using laser-induced time-resolved absorption or emission spectroscopy, and the contribution of an inner-filter effect in the presence of MIC in skimmed milk was evaluated by diffuse reflectance spectroscopy. The main operating mechanism of photoprotection is due to the deactivation of 3Rf* by the proteic component of gum arabic; thus, gum arabic based microcapsules could be used to improve the photostability of milk during its storage and/or processing under light.
authors.affiliation: Instituto de Ciencias Químicas, Faculdad de Agronomía y Agroindustrias, Universidad Nacional de Santiago del Estero, Av. Belgrano (S) 1912, 4200 Santiago del Estero, Argentina.
authors.forename: Mariana A
authors.initials: MA
authors.lastname: Montenegro
authors.forename: Itaciara L
authors.initials: IL
authors.lastname: Nunes
authors.forename: Adriana Z
authors.initials: AZ
authors.lastname: Mercadante
authors.forename: Claudio D
authors.initials: CD
authors.lastname: Borsarelli
mesh_terms: D000818:Animals; D002214:Capsules; D002338:Carotenoids / Q000008:administration & dosage*; D002762:Cholecalciferol / Q000737:chemistry / Q000528:radiation effects*; D004355:Drug Stability; D006170:Gum Arabic / Q000008:administration & dosage*; D008027:Light; D000077276:Lycopene; D008892:Milk / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D012995:Solubility; D014801:Vitamin A / Q000737:chemistry / Q000528:radiation effects*; D014867:Water
chemical_list: D002214:Capsules; D014867:Water; D014801:Vitamin A; D002762:Cholecalciferol; D002338:Carotenoids; D006170:Gum Arabic; D000077276:Lycopene