Effect of Sonication on the Properties of Flaxseed Gum Films Incorporated with Carvacrol

Abstract

Carvacrol is a natural compound known to be a highly effective antibacterial; however, it is a hydrophobic molecule, which is a limitation to its use within food packaging. Flaxseed gum (FG) films containing different contents of carvacrol (C) were produced by a film-casting method with sonication. The effects of sonication power and time on the properties of the FG-C films were investigated by measuring the film thickness, mechanical properties, contact angle, opacity, water vapor permeability (WVP), water sorption isotherm, Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry (DSC), antibacterial and antioxidant activities, and microstructure. The results showed that sonication power and time had significant effects on mechanical and barrier properties, film opacity, and degradability (p < 0.05). The tensile strength (TS) and elongation at break (EB) values exhibited an obvious improvement after sonication, and FG-0.5C-6030 had the lowest TS (33.40 MPa) and EB (4.46%) values. FG-C films formed a denser structure and the contact angle was improved as a result of sonication, which improved the integration of carvacrol into the FG matrix. In terms of microstructure, sonication resulted in a homogeneous and continuous crosssection of FG-C films, and regular surface and cross-sectional images were obtained through the highest acoustic intensity and longest time treatment. The FG films incorporated with carvacrol displayed antibacterial properties against Staphylococcus aureus, Vibrio parahaemolyticus, Shewanella putrefaciens, and Pseudomonas fluorescens, as well as increased antioxidant properties, and sonication was proven to enhance both of them.

Preparation and Characterization of Carboxymethyl Cellulose-Based Bioactive Composite Films Modified with Fungal Melanin and Carvacrol

“…The observed results suggest that this effect can be presumably attributed to some interactions between melanin and carvacrol in CMC matrix, lowering CV diffusion efficiency. The antibacterial activity of chitosan/CV [ 51 ], chitosan/CV/pomegranate peel extract [ 40 ], polypropylene/CV [ 31 ], flaxseed gum/CV [ 36 , 44 ], and PLA/CV [ 52 ] films, as well as PLA/CV [ 53 ] nanofibers, has been already reported. Carvacrol is a phenolic compound with a hydroxyl group on an aromatic ring.…”

“…The hydroxyl group of CV plays a crucial role in the antibacterial activity of this phytochemical [ 32 , 33 , 34 ]. Indeed, CV interacts with the lipid bilayer of the bacterial cytoplasmic membrane due to its hydrophobic nature and aligns itself between fatty acid chains causing the expansion and destabilization of the membrane structure by increasing its fluidity and permeability for protons and ions (mainly H + and K + ) [ 7 , 35 , 36 , 44 ]. The loss of the ion gradient leads to bacterial cell death [ 36 , 44 ].…”

“…Indeed, CV interacts with the lipid bilayer of the bacterial cytoplasmic membrane due to its hydrophobic nature and aligns itself between fatty acid chains causing the expansion and destabilization of the membrane structure by increasing its fluidity and permeability for protons and ions (mainly H + and K + ) [ 7 , 35 , 36 , 44 ]. The loss of the ion gradient leads to bacterial cell death [ 36 , 44 ]. However, the mechanisms of action of CV against Candida have been investigated in several studies and seems to exert its antifungal activity by inducing envelope, disrupting membrane integrity, and blocking ergosterol biosynthesis [ 33 ].…”

“…Furthermore, the possibility of melanins production by sustainable extraction from natural agricultural residues (e.g., waste from the harvesting of champignon mushroom, Agaricus bisporus, or residual watermelon seeds) has been demonstrated [ 13 , 17 ]. Another potential bioactive functional compound is carvacrol (CV, 5-isopropyl-2-methylphenol), a phenolic compound found primarily in oils of oregano, thyme, and marjoram, and recognized as a safe food additive (Generally Recognized as Safe—GRAS) [ 7 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. This bioactive compound possesses antimicrobial properties, antioxidant, and a particular aroma which makes an attractive ingredient for certain types of foods [ 37 , 38 ].…”

Biopolymers as Food Packaging Materials

“…Fang et al [ 9 ] produced, by casting method and sonication, an effective flaxseed gum film incorporated with carvacrol-possessing antioxidant and antimicrobial properties.…”