Journal of the Science of Food and Agriculture J Sci Food Agric 86:2431–2437 (2006) Spray-dried encapsulation of Conjugated Linoleic Acid (CLA) with polymeric matrices M Jimenez, 1,2 HS Garc´ ıa 1 and CI Beristain 2∗ 1 Instituto Tecnol ´ ogico de Veracruz. A. de Quevedo 2779, Veracruz 91897, Mexico 2 Instituto de Ciencias B ´ asicas, Universidad Veracruzana, Apdo Postal 575, CP 91000, Rafael S ´ anchez Altamirano, Industrial-Animas, 91192, Xalapa Veracruz, Mexico Abstract: Conjugated linoleic acid was encapsulated in three different matrices: whey protein concentrate (WPC), gum arabic (GA) and a blend of WPC and maltodextrin 10 DE (1:1, w/w). Kinetic studies on the degradation of CLA and lipid oxidation of microcapsules were carried out at water activities from 0.108 to 0.892 at 35 and 45 ◦ C. The highest values of CLA degradation and lipid oxidation were observed in the range of water activities 0.103–0.429 for all matrices at 45 ◦ C, whereas the lowest CLA degradation and lipid oxidation were observed for WPC at a water activity of 0.743 and 35 ◦ C. WPC microcapsules showed the best morphology and encapsulation efficiency and the lowest CLA degradation.  2006 Society of Chemical Industry Keywords: microencapsulation; conjugated linoleic acid; oxidative stability; wall material INTRODUCTION Conjugated linoleic acid (CLA) refers to a group of geometric and positional isomers of conjugated linoleic acid. It was originally isolated from ground beef extract principally as an anticancer agent and showed a vari- ety of biologically beneficial activities. 1 Unfortunately, free lipids are generally difficult to disperse in food ingredients and polyunsaturated fatty acids are sus- ceptible to oxidation, which results in the generation of off-flavors. 2 In vitro studies have show that free CLA is oxidized as rapidly as linoleic acid. 3,4 These studies suggest that free CLA must be protected from oxidation when it is used as a fortifier or additive. Encapsulation offers a potential to protect CLA from oxidation caused by light, heat and oxygen. Encapsu- lation is a technology to transform liquids into stable and free-flowing powders which are easy to handle and incorporate into dry food systems. Among encapsula- tion methods, spray drying is one of the best known and commonly used. 5,6 Microencapsulation of lipid materials susceptible to oxidation has been shown to retard oxidation significantly. 7,8 Numerous materials have been used as encapsulating agents, including proteins, gums and modified starches. 9–12 Gum ara- bic (GA) has excellent emulsification properties and it is widely used for the retention and protection of oils. However, GA is an expensive ingredient and its avail- ability and cost are subject to fluctuations, 13 hence there is a need to evaluate alternatives. Whey proteins have been reported to be effective for microencapsulation by the spray drying of anhydrous milk fat or volatiles. 14,15 Carbohydrates cannot be used as wall material in the absence of a surface- active wall constituent because they generally have no emulsification properties; 16 however, incorporating carbohydrates into the wall systems has been shown to improve the drying properties of the wall matrix. 17 Sometimes the mixture of encapsulating agents acts favorably or unfavorably for protection and retention of the core. 13 A blend of several ingredients can produce superior or lower performance compared with the use of one ingredient alone. Mixtures of whey proteins with natural or modified carbohydrates were used for microencapsulation of susceptible core materials. 18 – 20 The properties of the wall system can be designed in order to act as an effective barrier and their structural features are of essential importance to the functionality of the microcapsulated system. The inner and outer structure of the microcapsules and the related topography of the particles with the protection of the wall materials can be studied by scanning electron microscopy (SEM). Microencapsulation of CLA in cyclodextrin has been reported by Kim et al ., 21 who prepared microcapsules of CLA with a freeze- drier using different kinds of cyclodextrins (CDs). They found that α-cyclodextrin was the most effective for the protection of CLA oxidation. On the other hand, Park et al . 22 inserted the CLA molecule into the cavity of CDs, creating CLA/CD inclusion complexes, and found that the oxidation of CLA induced at 35 ◦ C for 80 h was completely prevented by the formation of CLA–CD inclusion complexes. ∗ Correspondence to: CI Beristain, Instituto de Ciencias B ´ asicas, Universidad Veracruzana, Apdo. Postal 575, CP 91000, Rafael S ´ anchez Altamirano, Industrial- Animas, Xalapa Veracruz, Mexico E-mail: cberistain@uv.mx (Received 17 January 2005; revised version received 23 May 2005; accepted 5 July 2006) Published online 6 September 2006; DOI: 10.1002/jsfa.2636  2006 Society of Chemical Industry. J Sci Food Agric 0022–5142/2006/$30.00