Carbohydrate Polymers 98 (2013) 17–25 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers jo ur nal homep age: www.elsevier.com/locate/carbpol Encapsulation of volatiles in nanofibrous polysaccharide membranes for humidity-triggered release Erika Mascheroni a,∗ , Carlos Alberto Fuenmayor a,b , Maria Stella Cosio a , Giuseppe Di Silvestro c , Luciano Piergiovanni a , Saverio Mannino a , Alberto Schiraldi a a Department of Food, Environmental and Nutritional Sciences (DEFENS), University of Milan, Via Celoria 2, 20133 Milan, Italy b Instituto de Ciencia y Tecnología de Alimentos (ICTA), Universidad Nacional de Colombia, Ciudad Universitaria, Av. Kr. 30 # 45-03, 111321 Bogotá, Colombia c Department of Chemistry, University of Milan, Via Golgi 19, 20133 Milan, Italy a r t i c l e i n f o Article history: Received 5 March 2013 Received in revised form 15 April 2013 Accepted 16 April 2013 Available online 30 April 2013 Keywords: Pullulan Cyclodextrins Encapsulation Aroma compounds Controlled release Nanofibers a b s t r a c t A single-step electrospinning process will be applied to a blend of edible carbohydrate polymers (pullulan and -cyclodextrin) to encapsulate bioactive aroma compounds and allow a humidity-triggered release. The encapsulation is rapid and efficient and the final product is an active nanofibrous membrane that can be directly used for food or active packaging applications. The membrane hosts small and homogeneously dispersed crystals of cyclodextrin–aroma complexes which are formed during the electrospinning. With this type of structure, the release of aroma compound is negligible at ambient conditions (23 ◦ C and 55% UR) even at high temperature (up to 230 ◦ C), and it occurs beyond a given relative humidity threshold (90%), useful for food packaging applications. The mass fraction of free aroma released is directly related to the water activity of the system, namely, ϕ = a n W /(a n W + K app ) explaining the observed key role played by the relative humidity on the release of the aroma compounds. © 2013 Elsevier Ltd. All rights reserved. 1. Introduction The growing concern for the promotion of health and preven- tion of disease through improved nutrition has led to numerous attempts to develop food-grade delivery systems, including active packaging, to encapsulate, protect and deliver bioactive com- ponents (Lesmes & McClements, 2009; López-Rubio, Sanchez, Wilkanowicz, Sanz, & Lagaron, 2012; Sozer & Kokini, 2008). Volatile substances with antimicrobial features, such as natural essential oils, absolutes, essences, extracts, resins, infusions, etc. are of great interest for the active packaging industry and their efficient encap- sulation and release represent a major challenge, considering their high fugacity and the fact that they are very sensitive to heat, oxy- gen and light. Most of the active packaging studies reported in the lit- erature concern the dispersion of the active agent in carriers with limited surface areas, such as polymer films and layers, sometimes with not negligible losses of volatile compounds during production and storage (Appendini & Hotchkiss, 2002; Guillard, Issoupov, Redl, & Gontard, 2009). The controlled release ∗ Corresponding author. Tel.: +39 02 50319232; fax: +39 02 50316672. E-mail address: erika.mascheroni@unimi.it (E. Mascheroni). of active substances from these structures is mainly governed by concentration-dependent passive diffusion (Vega Lugo & Lim, 2009). Recently, electrospinning has received great attention in func- tional food and active food packaging systems (Bhardwaj & Kundu, 2010; Chen, Remondetto, & Subirade, 2006; Kayaci & Uyar, 2012a, 2012b; Kriegel et al., 2008; Lagaron & Lopez-Rubio, 2011; Sanchez- Garcia, Lopez-Rubio, & Lagaron, 2010). This simple technique allows the production of nanofibrous polymeric unwoven mem- branes formed by polymer fibers with diameters ranging from tens to hundreds of nanometers (Frenot & Chronakis, 2003; Yua, Yanga, Quiana, & Lia, 2012; Zheng-Ming Huang, Zhang, & Kotaki, 2003). By virtue of their submicron to nano-scale diameter and very large surface area, electrospun fibers may offer a number of additional advantages compared to film and sheet carriers, as they are more responsive to changes in the surrounding atmo- sphere (e.g., relative humidity and temperature changes), which enables a tunable release of the entrapped compounds (Vega Lugo & Lim, 2009). Moreover, since the electrospinning process takes place at ambient conditions, electrospun fibers are more suitable to encapsulate thermally labile substances than fibers prepared by conventional melt spinning or films produced by extrusion pro- cess, or other encapsulation methods, such as spray drying and fluid bed coating (Qi, Hu, Xu, & Wang, 2006; Xu et al., 2006; Zuidam & 0144-8617/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.carbpol.2013.04.068