Chitosan/Thyme Oil Systems as Affected by Stabilizing Agent: Physical and Antimicrobial Properties

Abstract

Antimicrobial biopolymer films and coatings are of great interest for many applications. Different chitosan systems were prepared and characterized to evaluate the effect of their composition on the physical and antimicrobial properties. Three types of emulsifiers (Tween 20, 80, and 85) were used as stabilizing agents, combined with thyme essential oil (from two producers) applied as an active substance. A predominant role of the applied stabilizer and its hydrophilic–lipophilic balance value was proven. The incorporation of thyme essential oil and surfactant into the chitosan matrix led to a significant decrease of particle size in film-forming solutions, as well as a thickness increase and the enhancement of the barrier properties in chitosan films. Antimicrobial effects were provided even at the lowest tested concentration of thyme essential oil. Hence, the prepared chitosan films represent promising candidates in antimicrobial packaging applications.

Zein-Based Films Containing Monolaurin/Eugenol or Essential Oils with Potential for Bioactive Packaging Application

“…Following the incorporation of active compounds, a drop in tensile strength was recorded, with the values ranging from 1.5 MPa for the 5ML/2O zein film to 7.9 MPa for the film containing 3 wt% of oregano oil. Decrease tensile properties caused by the addition of various hydrophobic agents into the polymer matrix was also seen in other studies [ 8 , 9 ]. The reason for this may be the loosened polymer structure due to the mutual estrangement of polymer chains leading to the decreased tensile characteristics.…”

“…The prepared samples were analyzed using the tensile and puncture tests, since these aspects play a crucial role in determining the integrity of packaging materials during the application, transport, and storage processes. The highest tensile strength, which is defined as the maximum stress exerted on a sample [ 8 ], was shown by the control zein sample (11.6 MPa), as can be seen in Figure 1 a. Following the incorporation of active compounds, a drop in tensile strength was recorded, with the values ranging from 1.5 MPa for the 5ML/2O zein film to 7.9 MPa for the film containing 3 wt% of oregano oil.…”

“…The usual trend was confirmed that a less rigid structure with lower tensile strength was associated with increased material elasticity and vice versa, which as shown by comparing Figure 1 a,b [ 12 ]. The lower plasticizing activity of thyme oil could be ascribed to phenolic–phenolic interactions between thymol molecules, which are predominant in this type of essential oil [ 8 , 12 ].…”

Polysaccharides as Edible Films and Coatings: Characteristics and Influence on Fruit and Vegetable Quality—A Review

“…Surfactants are intended to reduce the overall tackiness of edible films and coatings. Non-ionic surfactants approved for use in food products are tweens (Tween 20, Tween 80 and Tween 85) and spans (Span 80) [204][205][206].…”

Synthesis, Controlled Release, and Stability on Storage of Chitosan-Thyme Essential Oil Nanocapsules for Food Applications

“…Several studies focus on the nanoencapsulation of various essential oils; most of the efforts are focused on finding the optimal preparation conditions as an effect of encapsulating, stabilizing polymers and aspects of antioxidant parameters and antimicrobials [ 10 , 11 , 12 ]. In this sense, numerous investigations report the nanoencapsulation of thyme essential oil in chitosan as a polymeric matrix [ 13 , 14 , 15 ]. However, the kinetic, antioxidant, and physical stability changes given by storage time and temperature conditions have not been thoroughly evaluated.…”