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

Shiyuan Fang,Jing Xie,Weiqiang Qiu,Jun Mei

doi:10.3390/ijms21051637

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.

Highlights

When directly applying antibacterial agents onto a food surface, their antibacterial activities are reduced owing to their quick spread into foods, denaturation with the food components, and inhibition of food-borne pathogens
The film thickness only changed slightly from 0.080 to 0.085 mm, and remained relatively stable (Table 2). This result suggests that sonication did not affect the thickness variation of the prepared Flaxseed gum (FG)-C films
Sonication was successfully applied in the production of FG-C films

Summary

Introduction

When directly applying antibacterial agents onto a food surface, their antibacterial activities are reduced owing to their quick spread into foods, denaturation with the food components, and inhibition of food-borne pathogens. Antibacterial agents in edible films can slowly and continuously migrate from the packaging material to the surface of the food and extend the shelf life of food. Alves et al [9] found that chitosan films with grape seed extract and carvacrol microcapsules could increase the shelf life of refrigerated salmon to 4–7 days of storage owing to the antibacterial effect of the natural agents. A huge number of cavitation bubbles are formed, grown, oscillated, and burst during the propagation of ultrasound, and high local pressure (5 GPa) generates in a very short time, which causes the emulsion droplets to be dispersed uniformly. Rodrigues et al [12] reported that sonication caused mesquite seed gum and palm fruit oil emulsion droplets to be dispersed more uniformly, with their surface hydrophilicity and tensile strength (TS) increased

Methods

Results

Conclusion