Pullulan Films Containing Rockrose Essential Oil for Potential Food Packaging Applications

Abstract

Active packaging is designed to control the development of decay- and disease-causing microorganisms and is emerging as a promising technology for extending shelf-life, maintaining food safety, reducing waste, and minimizing the risks for foodborne diseases. The goal of this work was to develop and characterize bioactive pullulan-based films, containing rockrose (Cistus ladanifer) essential oil. Among other abundant compounds (camphene, bornyl acetate and trans-pinocarveol), α-pinene was identified as the major compound of rockrose essential oil (39.25%). The essential oil presented stronger antibacterial activity against Gram-positive than against Gram-negative bacteria. The antioxidant results indicate the potential of the developed films to be used to package foods susceptible to oxidation and rancification, thus improving their shelf-life. Also, this study reflects the potential of rockrose essential oil, free or incorporated in pullulan, as a promising quorum sensing inhibitor, since it was able to interrupt intercellular communication, inhibiting violacein production. Electronic microscopy images showed the antibiofilm activity of the films with rockrose essential oil that were able to influence bacterial adhesion, which may be explained by the differences in the surface free energy of the films, as also determined.

Pullulan–Apple Fiber Biocomposite Films: Optical, Mechanical, Barrier, Antioxidant and Antibacterial Properties

“…Pullulan films not including apple fiber were also produced, to be used as a control. Finally, the dried films were detached from the Petri dishes and kept under controlled relative humidity (RH) (50 ± 5%) and temperature (23 ± 2 °C) [ 1 , 2 , 4 , 12 , 13 ].…”

“…A Nicolet iS10 smart iTRBasic Thermo Fisher Scientific (Waltham, MA, USA) was used to obtain the Fourier-Transform Infrared Spectroscopy (FTIR) spectra of the biocomposite films between 600 and 4000 cm −1 , acquiring 120 scans with 4 cm −1 of resolution [ 12 ].…”

“…A calorimeter Netzsch DSC 204 (GWP, Munich, Germany) was used to obtain the Differential Scanning Calorimetry (DSC) thermograms of the biocomposite films, functioning with the following conditions: an inert atmosphere, a heating rate of 5 °C/min, and a temperature ranging from 25 to 500 °C. Before the study, samples of the films were maintained at 105 °C for 24 h to totally evaporate the water, also being obtained the respective baselines [ 12 ].…”

“…The biocomposite films’ grammage was determined by the quotient between their mass and area (g/m 2 ), according to the ISO 536:1995. An Adamel Lhomargy Model MI 20 micrometer (TMI, Veenendaal, Netherlands) was used to measure the thickness (µm) of the films, considering different random assessments, following the ISO 534:2011 [ 12 , 13 ].…”

“…The mechanical properties of the biocomposite films (Peak Elongation (%), Tensile Index (N m/g), Tensile Strength (N/m), and Elastic Modulus (MPa)) were determined using a Thwing-Albert Instrument Co. (West Berlin, NJ, USA) tensile tester, adjusting the crosshead at 10 mm/min, and the initial grip at 50 mm, following the ISO 1924/1 [ 12 , 13 ].…”