Thermal degradation of antioxidant micronutrients in citrus juice: kinetics and newly formed compounds.
The thermal degradation kinetics of vitamin C, two carotenoids (beta-carotene and beta-cryptoxanthin), and hesperidin, as a function of temperature, were determined for Citrus juice [Citrus sinensis (L.) Osbeck and Citrus clementina Hort. ex Tan]. The influence of dissolved oxygen on the rate of ascorbic acid degradation was also assessed. Analysis of kinetic data suggested a first-order reaction for the degradation of vitamin C and carotenoids. The kinetics parameters Dtheta, z, and Ea have been calculated. Following the Arrhenius relationship, the activation energy of ascorbic acid was 35.9 kJ mol-1 and agreed with the range of literature reported value. The results on vitamin C and carotenoids from citrus juice made it possible to validate the predicting model. Thermal degradation of carotenoids revealed differences in stability among the main provitamin A carotenoids and between these and other carotenoids belonging to the xanthophyll family. The activation energies for the two provitamin A carotenoids were 110 and 156 kJ mol-1 for beta-carotene and beta-cryptoxanthin, respectively. On the other hand, no degradation of hesperidin was observed during thermal treatment. Finally, the vitamin C in citrus juice was not as heat sensitive as expected and the main provitamin A carotenoids present in citrus juice displayed a relative heat stability. The high-performance liquid chromatography-diode array detection-mass spectrometry analysis of degradation products showed that the isomerization of the epoxide function in position 5,6 into a furanoxide function in position 5,8 was a common reaction for several xanthophylls. These findings will help determine optimal processing conditions for minimizing the degradation of important quality factors such as vitamin C and carotenoid in citrus juice.
Dhuique-Mayer
Claudie
C
Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Département PERSYST UMR 95 Tropical Food Quality, TA B-95/16, 73 Av. J.F Breton 34398, Montpellier Cedex 5, France. claudie.dhuique-mayer@cirad.fr
Tbatou
Manal
M
Carail
Michel
M
Caris-Veyrat
Catherine
C
Dornier
Manuel
M
Amiot
Marie Josephe
MJ
D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D001628:Beverages / Q000032:analysis*; D002338:Carotenoids / Q000737:chemistry; D002957:Citrus / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry*; D006569:Hesperidin / Q000737:chemistry; D006358:Hot Temperature; D007700:Kinetics; D018977:Micronutrients / Q000737:chemistry*
D000975:Antioxidants; D018977:Micronutrients; D002338:Carotenoids; D006569:Hesperidin; D001205:Ascorbic Acid