36D-15 |
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C. PÉREZ-ALONSO, Facultad de Quimica, Univ. Autonoma del Estado de Mexico, Paseo Tollocan esq. Paseo Colón S/N, Toluca, Edo. Mex., 50180, Mexico, J. G. Báez-González, IPH, Univ. Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco # 186, Mexico City, 09340, Mexico, M. E. Rodríguez-Huezo, BT, Univ. Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco # 186, Mexico City, 09340, Mexico, C. I. Beristain, Instituto de Ciencias Básicas, Univ. Veracruzana, Apartado Postal #575, Xalapa, Veracruz, 91000, Mexico, and E. J. Vernon-Carter, IPH, Univ. Autónoma Metropolitana Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, Mexico City, 09340, Mexico. The surface fractal dimension (DS) is useful for characterizing particle surface roughness. The value of DS varies from 2 for a perfectly smooth surface to 3 for a very rough surface. DS can be used to investigate structural features of microcapsules and such data can be used to optimize or maximize the protection, retention, or controlled release of the core material, as these properties are intimately related to surface topology and inner microstructure of the microcapsules. The purpose of this work was to determine DS for pure gum Arabic (GA100%), mesquite gum (MG100%), maltodextrin DE 10 (MD100%) and a blend of the gums (GA17%-MG66%-MD17%), and for two spray-dried microcapsules containing carotenoids using as wall materials GA100% (M1) and GA17%-MG66%-MD17% (M2). The value of DS for the biopolymers and microcapsules was compared in order to establish if DS of biopolymers is useful for predicting the functionality of microcapsules made up with them. Biopolymers and microcapsules were stored at water activities between 0.108 to 0.821 and at 25, 35 and 40° C, respectively. Water vapor adsorption isotherms data were obtained and fitted to GAB's model. The monolayer water content constant M0 was used for estimating DS with the Frenkel-Helsey-Hill modified theory. Degradation kinetics and surface carotenoids of microcapsules were determined spectrophotometrically at 460 nm. The value of DS varied with increasing temperature as follows: 2.40, 2.45, 2.46 (GA100%); 2.17, 2.20, 2.22 (MG100%); 2.30, 2.21, 2.12 (MD100%); 2.25, 2.28, 2.37 (GA17%-MG66%-MD17%); 2.39, 2.44, 2.49 (M1); and 2.25, 2.27, 2.33 (M2). Surface carotenoids and degradation kinetics of the carotenoids were higher for M1 than for M2, indicating that more irregular shaped microcapsules are more likely to have surface flaws, and less likely to retain and protect the core material. DS of biopolymers can be used for predicting spray-dried microcapsules functionality.
Session 36D, Food Engineering: Rheology
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |