Protection of Active Aroma Compound against Moisture and Oxygen by Encapsulation in Biopolymeric Emulsion-Based Edible Films Alicia Hambleton, † Fre ´de ´ ric Debeaufort,* ,†,‡ Laurent Beney, § Thomas Karbowiak, 4 and Andrée Voilley † ENSBANA-EMMA, Universite ´ de Bourgogne, 1 esplanade Erasme, F-21000 Dijon, France, IUT-Gen ´ie Biologique, Boulevard Dr. Petitjean, BP 17867, F-21078 Dijon, France, ENSBANA-GPMA, Universite ´ de Bourgogne, 1 esplanade Erasme, F-21000 Dijon, France, and IUVV, Universite ´ de Bourgogne, Rue Claude Ladrey BP 27877, 21078 Dijon Cedex, France Received November 8, 2007; Revised Manuscript Received December 21, 2007 Edible films made of ι-carrageenans display interesting advantages: good mechanical properties, stabilization of emulsions, and reduction of oxygen transfers. Moreover, the addition of lipids to ι-carrageenan-based films to form emulsified films decreases the transfer of water vapor and can be considered to encapsulate active molecules as flavors. The aim of this study was to better understand the influence of the composition and the structure of the carrageenan-based film matrices on its barrier properties and thus on its capacity to encapsulate and to protect active substances encapsulated. Granulometry, differential scanning calorimetry, and Fourier transform infrared spectroscopy characterizations of films with or without flavor and/or fat showed that the flavor compound modifies the film structure because of interactions with the ι-carrageenan chains. The study of the water vapor permeability (WVP), realized at 25 and 35 °C and for three relative humidity differentials (30–100%, 30–84%, 30–75%), showed that the flavor compound increases significantly the WVP, especially for the weaker gradients, but has no effect on the oxygen permeability. This study brings new understanding of the role of carrageenan as a film matrix and on its capacity to protect encapsulated flavors. 1. Introduction The conservation of food products requires the maintenance of their initial properties in protecting them from the environ- ment and in limiting the transfers and losses of matter. 1 To preserve the quality of the food product and to avoid its degradation, food packagings are used. Several works on the understanding of the mass transfer mechanisms in food product packaging (traditional and edible) have been published in recent years. Only edible packaging are effective to control the transfers within composite food. 2 Edible packagings (films or coatings) have been defined as “a packaging as a film, a coating or a thin protective layer which is an integral part of the food and/or can be eaten with”. The oldest applications known were used in China since the 12th and 13th centuries to delay the dehydration of citrus. 3 Edible films are obtained from hydrocolloids (protein, polysaccharides), which provide film cohesion, mechanical properties, and impermeability of aroma compounds and lipids 4 but have low water barrier properties, 2 often used for flavor encapsulation or for medicine tablets, and/or lipids, which have poor mechanical properties but greatly reduce water transfer. These films can be used to limit the superficial dehydration of humid and/or frozen food products and to reduce the moisture transfer between components of a multidomain food product. 5 The concept of complex packaging, combining hydrocolloids and lipids, allows edible films with good mechanical and water barrier properties. These edible films can either be bilayer or dried emulsion. Emulsified films improved water barrier proper- ties, and their production is a single one-step process. 6 ι-Carrageenan-based edible films have good mechanical characteristics, are emulsion stabilizers, and decrease oxygen transfer. The addition of lipids to form emulsified films decreases the water vapor transfer and could be used to encapsulate active molecules or aroma compounds. 6 Interactions between the hydrocolloids and the lipids are going to determine the film’s stability and properties. 7 Hydrocolloids usually form a homogeneous network in which the lipids are dispersed. Several authors have shown that lipids forming crystals such as waxes decrease water transfer. Anker et al. 8 and Karbowiak et al. 9 have shown that the water permeability decreases when the concentration of lipids is close to 30% and the fat globules have small diameter. Carrageenans are a class of sulfated polysaccharides, soluble in water, extracted from marine resources which are constituents of the cell of various red seaweeds (Rhodophyceae). The number and position of sulfate groups on the disaccharide repeated unit determine classification in three major types: kappa (κ), iota (ι), and lamda (λ). The κ-, ι-, and λ-carrageenans exhibit sulfate content of 20, 33, and 41% (w/w), respectively. They are widely used in the food industry to improve thickening and texture and to stabilize food products. Moreover they are a renewable resource and commercially available at a reasonable cost. ι-Carrageenan is composed of altering R(1,3)-D-galactose-4- sulfate and (1,4)-3,6-anhydro-D-galactose-2-sulfate. In aqueous solutions, ι-carrageenans produce thermoreversible gels (50–55 °C) forming a tridimensional network with double-helix chains, each pair of helixes being 13.9 Å laterally spaced, therefore a compact, dense, and organized film structure. ι-Carrageenan * Author to whom correspondence should be addressed. E-mail: frederic.debeaufort@u-bourgogne.fr. † ENSBANA-EMMA, Universite ´ de Bourgogne. ‡ IUT-Gen ´ie Biologique. § ENSBANA-GPMA, Universite ´ de Bourgogne. 4 IUVV, Universite ´ de Bourgogne. Biomacromolecules 2008, 9, 1058–1063 1058 10.1021/bm701230a CCC: $40.75  2008 American Chemical Society Published on Web 02/08/2008