Produção de fibras ultrafinas de zeína incorporadas com complexo de inclusão de β-ciclodextrina e óleo essencial de eucalipto (Eucalyptus citriodora) com atividade antimicrobiana, pela técnica de Electrospinning

Abstract

Microbial control is a constant concern in the food packaging industry. Active packaging is capable of inhibiting microbial growth in food. In addition, the use of biodegradable polymers has been extensively studied. Zein is a biodegradable polymer that has great potential in the packaging industry and can encapsulate bioactive compounds in its polymer matrix. Essential oils (EO) are naturally occurring bioactive compounds due to the secondary metabolism of some plants and have been studied as antimicrobial agents in active packaging. However, complexation with some molecule is necessary in order to reduce some undesirable characteristics, such as high volatility. Cyclodextrins are cone-shaped molecules capable of accommodating apolar molecules such as essential oils. An effective technology capable of incorporating bioactive compounds into nanomaterials is the electrospinning technique. The objective of this study was to produce ultrafine zein fibers by incorporating an inclusion complex (IC) between β-Cyclodextrin (β-CD) and eucalyptus essential oil (EO) through the electrospinning technique in order to Antimicrobial membranes as active food packaging. The EEO was characterized by the chemical composition and antimicrobial activity against 7 bacteria of importance in food. CI was evaluated for functional groups, morphology and thermal properties. Polymer solutions of pure zein at different concentrations were evaluated for apparent viscosity and electrical conductivity and the resulting membranes after the electrospinning process were evaluated for morphology and diameter distribution. The 30% (w/v) zein solutions were added with IC at concentrations of 6, 12, 18 and 24% (w/v), which were characterized for apparent viscosity and electrical conductivity. After the electrospinning process of IC solutions, these membranes were evaluated for morphology and diameter distribution, thermal properties, functional groups and micro-atmosphere antimicrobial activity against S. aureus and L. monocytogenes. The results indicated antimicrobial activity of EEO against all tested bacteria. Through the analysis of functional groups and morphology, an effective complexation of EEO and β-CD can be observed. The fibers obtained with 30% (w/v) zein in the polymer solution showed better morphological characteristics. All membranes formed with IC reduced the microbial growth of S. aureus and L. monocytogenes. The concentration of 24% (w/v) IC was obtained with the highest percentage of growth reduction in micro-atmosphere, with 24.3% and 28.5% for S. aureus and L. monocytogenes, respectively. The antimicrobial membranes showed characteristics for possible application as active food packaging.