a b s t r a c tThe aim of this research was to evaluate the plasticizing effect of natural surfactants lecithin or yucca extract from Yucca schidigera on gelatin-based films. Films containing yucca extract showed higher tensile strength values ($90-40 MPa) and moisture contents ($15%) and less elongation ($5%) and water vapor permeability values ($0.22-0.09 g mm m À2 h À1 kPa À1 ) compared to films containing lecithin. Soluble films ($20-50%) were obtained when yucca extract was used while lecithin produced low soluble films (<10%). The opacity of the films ($14.5-16.2%) was similar for both surfactants and the film surface morphologies were continuous and homogeneous. X-ray diffraction indicated that the addition of surfactants produced amorphous films compared to gelatin-based films and FT-Infrared spectroscopy showed no evidence of association between the surfactants and the gelatin. The plasticizing effect was not obtained after surfactants addition and casting technique.

a b s t r a c tGelatin-based films containing both Yucca schidigera extract and low concentrations of glycerol (0.25-8.75 g per 100 g protein) were produced by extrusion (EF) and characterized in relation to their mechanical properties and moisture content. The formulations that resulted in either larger or smaller elongation values were used to produce films via both blown extrusion (EBF) and casting (CF) and were characterized with respect to their mechanical properties, water vapor permeability, moisture content, solubility, morphology and infrared spectroscopy. The elongation of the EF films was significantly higher than that of the CF and EBF films. The transversal section possessed a compact, homogeneous structure for all of the films studied. The solubility of the films (36-40%) did not differ significantly between the different processes evaluated. The EBF films demonstrated lower water vapor permeability (0.12 g mm m À2 h À1 kPa À1 ) than the CF and EF films. The infrared spectra did not indicate any strong interactions between the added compounds. Thermoplastic processing of the gelatin films can significantly increase their elongation; however, a more detailed assessment and optimization of the extrusion conditions is necessary, along with the addition of partially hydrophobic compounds, such as surfactants.

Essential oils are widely employed in food industry as natural flavors, however, these compounds are very difficult to handle due to they are very susceptible to oxidation and volatilization during process and storage generating undesirable flavors, therefore, it is necessary to use a protection method as microencapsulation. Chemical and thermo‐mechanically modified rice starch was used as wall material together with native rice starch, maltodextrin, and protein to microencapsulate orange essential oil by a spray‐drying technology. Microcapsules obtained were characterized in encapsulation efficiency (%EE), encapsulation yield (%YE), solubility, humidity (%), water activity (Aw), and color difference (ΔE). Through a surface response analysis, best formulations were selected and evaluated by its microestructure and stability of encapsulated essential oil. Results showed that the best encapsulating agent was the one with modified rice starch as predominant ingredient (>50%) of the wall material, showing higher efficiency than commercial encapsulating ingredients. Practical applications Microencapsulation is widely employed in food industry due to its ability to protect a compound of interest from adverse conditions that can generate decomposition of it or, in terms of flavor compounds, the generation of undesirable aroma and flavor characteristics. A lot of wall materials have been used to develop microencapsulation, however, starch is one of the main natural wall materials employed in microencapsulation by spray‐drying due to its high encapsulation efficiency. Rice starch is proposed in this study because is an abundant raw material, has the property of generate spherical aggregates and, together with another wall materials (maltodextrin and protein), can generate a resistant wall material with high encapsulation efficiency. Furthermore, the modification of rice starch involves a less employment of reactives, due to the thermomechanical process, obtaining a starch with more affinity to nonpolar compounds (essential oil), low viscosity, and solubility at room temperature (25 °C); which made this, an environmental friendly process. The procurement of the best wall material formulation suitable for encapsulation by spray drying, is of primary importance in order to preserve the quality and integrity of the encapsulated essential oil by reducing the presence of oxidation byproducts, increasing the shelf life and improving with this, its application inside a food matrix. Once the best wall material formulation is obtained, it can be used for the encapsulation of any type of essential oils used in the food industry.

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