Development of electrospun active films of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) by the incorporation of cyclodextrin inclusion complexes containing oregano essential oil

This paper reports the development of biodegradable active packaging films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by the incorporation of alpha- and gamma-cyclodextrins (alpha-CD and gamma-CDs) containing oregano essential oil (OEO). Herein, both the kneading method (KM) and freeze-drying method (FDM) were first explored for the preparation of alpha-CD:OEO and gamma-CD:OEO inclusion complexes at host:guest ratios of 80:20 wt/wt and 85:15 wt/wt, respectively. The results showed that KM was the most efficient method for the encapsulation of OEO in the CDs cavity in terms of simplicity and rapidity, while it was also yielded the inclusion complexes with the highest antimicrobial and antioxidant performance. The alpha-CD:OEO and gamma-CD:OEO inclusion complexes obtained by KM were thereafter incorporated at 10, 15, 20, 25, and 30 wt% into PHBV fibres by electrospinning and annealed at 160 degrees C to produce contact transparent films. It was observed that the optimal concentration of alpha-CD:OEO and gamma-CD:OEO inclusion complexes for homogeneous and continuous film formation was attained at contents of 15 and 25 wt%, respectively. Higher antimicrobial and antioxidant activities were obtained for the gamma-CD:OEO inclusion complexes due to the greater encapsulation efficiency of OEO in gamma-CD, resulting in PHBV films with good performance for up to 15 days. This aspect, together with their improved thermal stability and mechanical strength, give interesting applications to these biopolymer films in the design of active-releasing packaging materials to maintain the physical, chemical, and microbiological characteristics of food products.