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Type: Artigo de periódico
Title: Photoprotection of vitamins in skimmed milk by an aqueous soluble lycopene-gum arabic microcapsule
Author: Montenegro, MA
Nunes, IL
Mercadante, AZ
Borsarelli, CD
Abstract: Riboflavin (Rf)-mediated photosensitized degradation of vitamins A and D-3 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 E-a as being 4 and 16 kcal/mol for vitamins A and D-3, 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, (3)Rf*, and/or singlet molecular oxygen, O-1(2). The interaction of both (3)Rf* and O-1(2) 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 (3)Rf* 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.
Subject: photooxidation
triplet states
singlet oxygen
lycopene-gum arabic microcapsules
Country: EUA
Editor: Amer Chemical Soc
Rights: fechado
Identifier DOI: 10.1021/jf0622883
Date Issue: 2007
Appears in Collections:Unicamp - Artigos e Outros Documentos

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