Light stability of spray-dried bixin encapsulated with different edible polysaccharide preparations M.I.M.J. Barbosa a , C.D. Borsarelli b , A.Z. Mercadante a, * a Department of Food Science, Faculty of Food Engineering, State University of Campinas (UNICAMP), P.O. Box 6121, CEP 13083-970 Campinas, Brazil b Instituto de Ciencias Quı ´micas, Faculdad de Agronomı ´a y Agroindustrias, Universidad Nacional de Santiago del Estero, Santiago del Estero, Argentina Received 2 June 2004; accepted 27 February 2005 Abstract Bixin was encapsulated by spray-drying with gum arabic or maltodextrin, and the stability was evaluated in aqueous solution both under illumination or in the dark at 21 °C. The microcapsules containing emulsifier, such as gum arabic or maltodex- trin + Tween 80, showed the highest encapsulation efficiency, respectively 86% and 75%, less superficial imperfections and higher stability than bixin encapsulated with maltodextrin alone or blended with sucrose. The kinetic behavior of bixin photodegradation in all encapsulated systems was composed by two first-order decays, due to the presence of bixin outside and inside the microcap- sules. Bixin encapsulated with gum arabic was 3 to 4 times more stable than that encapsulated with maltodextrin. In all systems, greater bixin stability (<two orders of magnitude) was observed in the dark than under illuminated conditions. In addition, 10 times greater bixin stability was observed for encapsulated solutions as compared to the non-encapsulated systems in the absence of light. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Annatto; Bixin; Microencapsulation; Photodegradation; Kinetics; Microstructure 1. Introduction Annatto (Bixa orellana L.), known as urucum in Brazil, is a small tree native to the Central and South American rain forests and these days is cultivated in many countries in South and Central America, Africa and Asia. The tree produces clusters of fruits covered by flexible thorns, which contain red seeds inside them from which an orange-red dye is extracted. The annatto colorants are used to color a wide range of foods, such as dairy products, bakery products, fish, soft drinks, meat products, snack foods and powdered dry mixes (Preston & Rickard, 1980). More than 80% of the total pigments in the seeds coat consists of the carotenoid bixin, 6-methyl hydrogen 9 0 -cis-6,6 0 -diapocarotene-6,6 0 -dioate (Preston & Ric- kard, 1980). The long system of conjugated double bonds present in the structure of bixin is responsible for the red color, but also for the poor stability of the molecule under processing and storage conditions such as high temperature, light and oxygen (Montenegro, Rios, Nazareno, Mercadante, & Borsarelli, 2004; Najar, Bobbio, & Bobbio, 1988; Rios, Borsarelli, & Merca- dante, 2005; Scotter, Wilson, Appleton, & Castle, 1998). One of the alternatives used to improve carotenoid stability is the microencapsulation technique, which entraps a sensitive ingredient inside a coating material. The structure formed around the microencapsulated substance (core) is called the wall. Of the techniques available for microencapsulation, spray-drying, a well-known technology in the food industry, is the most commonly used. The wall materials most fre- quently used include gums, maltodextrins of different 0963-9969/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2005.02.018 * Corresponding author. Fax: +55 19 3788 2153. E-mail address: azm@fea.unicamp.br (A.Z. Mercadante). www.elsevier.com/locate/foodres Food Research International 38 (2005) 989–994