DSC thermo-oxidative stability of red chili oleoresin microencapsulated in blended biopolymers matrices C. Pe ´rez-Alonso a, * , J. Cruz-Olivares a , J.F. Barrera-Pichardo a , M.E. Rodrı ´guez-Huezo b , J.G. Ba ´ez-Gonza ´lez b , E.J. Vernon-Carter b a Facultad de Quı ´mica, Universidad Auto ´ noma del Estado de Me ´xico, Paseo Tollocan esq. Paseo Colo ´ n S/N, CP 50120, Toluca, Estado de Me ´xico, Mexico b Departamentos de BT e IPH, Universidad Auto ´ noma Metropolitana-Iztapalapa, San Rafael Atlixco #186, CP 09340 Mexico, D.F., Mexico Received 21 March 2007; received in revised form 27 August 2007; accepted 30 August 2007 Available online 7 September 2007 Abstract Red chili oleoresin-in-water emulsions were spray-dried to obtain microcapsules with wall to core ratios of 2:1 and 4:1. The biopoly- mers mesquite gum (MG), maltodextrin DE 10 (MD) and whey protein concentrate (WPC) were used as wall materials in two different ratios (WPC17%–MG17%–MD66% w/w and WPC66%–MG17%–MD17% w/w). The activation energy of microcapsules stored at dif- ferent water activities (a w ) was determined by non-isothermal dynamic regime differential scanning calorimetry (DSC), and was consid- ered as indicative of thermo-oxidative stability. Best protection against oxidation was achieved when maltodextrin predominated in the biopolymers blends, the wall to core ratio was 4:1 and a w was 0.436. Under these conditions the activation energy required for oxidizing the microcapsule was highest having a value of 98.5 kJ mol 1 . Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Thermo-oxidative stability; Red chili oleoresin; Activation energy; Water activity; Biopolymers blends 1. Introduction Color is an important parameter of food, as it may influ- ence the acceptance or rejection of products by consumers, serving as a visual indicator of food quality. Colorants are commercially available in a wide range of colors and pre- sentations, and may be added to foodstuffs so that they exhibit uniform color (Newsome, 1990; Pszczola, 1998). A healthy food trend has existed among consumers that has driven industry to develop healthful foods that contrib- ute to improve or preserve health (Pszczola, Katz, & Giese, 2000), but that also have better taste and consumer appeal (Sloan, 2006). Thus, natural colorants such as carotenoids, are a natural food ingredient choice to be used in the design of new functional foods. There is epidemological evidence that suggests that certain carotenoids may provide protec- tion against cancer and other degenerative diseases influ- enced by free radical reactions (Giovannucci, 1999; Nguyen & Schwartz, 2000), while others have pro-vitamin A effects (Delgado-Vargas & Paredes-Lo ´pez, 2003). Carotenoids are very sensitive to oxidative decomposition and isomerization, so that precautions have to be taken when handling them to avoid degradation and the forma- tion of artifacts such as epoxides (Britton, 1996). The potential market for water-dispersible preparations of natural carotenoids is huge and includes soft drinks, ice cream, desserts, candies, soups and meat products. These preparations must have good stability against oxidation and isomerization, and adequate solubility properties (Rodrı ´guez-Huezo, Pedroza-Islas, Prado-Barragan, Beri- stain, & Vernon-Carter, 2004). Microencapsulation by spray-drying is a widely employed technique used in the food industry for protect- ing foods or food ingredients against deteriorative factors and for converting liquids into functional powders that 0260-8774/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2007.08.020 * Corresponding author. Tel.: +52 7222173890; fax: +52 7222175109. E-mail address: cepa@uaemex.mx (C. Pe ´rez-Alonso). www.elsevier.com/locate/jfoodeng Available online at www.sciencedirect.com Journal of Food Engineering 85 (2008) 613–624