Basil Essential Oil: Composition, Antimicrobial Properties, and Microencapsulation to Produce Active Chitosan Films for Food Packaging

Abstract

The essential oil (EO) from basil-Ocimum basilicum-was characterized, microencapsulated by vibration technology, and used to prepare a new type of packaging system designed to extend the food shelf life. The basil essential oil (BEO) chemical composition and antimicrobial activity were analyzed, as well as the morphological and biological properties of the derived BEO microcapsules (BEOMC). Analysis of BEO by gas chromatography demonstrated that the main component was linalool, whereas the study of its antimicrobial activity showed a significant inhibitory effect against all the microorganisms tested, mostly Gram-positive bacteria. Moreover, the prepared BEOMC showed a spheroidal shape and retained the EO antimicrobial activity. Finally, chitosan-based edible films were produced, grafted with BEOMC, and characterized for their physicochemical and biological properties. Since their effective antimicrobial activity was demonstrated, these films were tested as packaging system by wrapping cooked ham samples during 10 days of storage, with the aim of their possible use to extend the shelf life of the product. It was demonstrated that the obtained active film can both control the bacterial growth of the cooked ham and markedly inhibit the pH increase of the packaged food.

Keywords: basil essential oil; chitosan film; cooked ham; food packaging; food shelf life; microencapsulation.

Figure 1

Cooked ham samples wrapped with chitosan films (A) containing 1% (B), 2% (C), or 3% (D) basil essential oil microcapsules; control unwrapped cooked ham (E).

Figure 2

Optical microscopy image of basil essential oil microcapsules before (a) and after (b) washing with sterile water.

Figure 3

SEM image of basil essential oil microcapsules immediately after their production.

Figure 4

Viable counts (Log CFU/mL) of different microorganisms grown in contact with basil essential oil microcapsules. E. coli (A), D1203 (B), ES1 (C), 7R1 (D).

Figure 5

Thickness and mechanical properties (TS, EB, and YM) of CH films, obtained at pH 4.5 in the presence of 30% glycerol and different concentrations of basil essential oil microcapsules. The asterisks indicate the values significantly different at p < 0.05 from those obtained with CH films prepared in the absence of basil essential oil microcapsules.

Figure 6

Effect of different concentrations of basil essential oil microcapsules on the opacity of CH films obtained at pH 4.5 in the presence of 30% glycerol. The asterisks indicate the values significantly different at p < 0.05 from those obtained with CH films prepared in the absence of basil essential oil microcapsules.

Figure 7

Antimicrobial activity of chitosan (CH) films grafted with different amounts of basil essential oil microcapsules (MC) against E. coli Panel (A) and S. saprophyticus 3S Panel (B). The asterisks indicate the values significantly different at p < 0.05 from those obtained without film addition (control) or with CH films prepared in the absence of basil essential oil MC.

Figure 8

Inhibitory effect on bacterial growth of different concentrations of basil essential oil microcapsules (MC) present in chitosan (CH) films used to wrap cooked ham at different times of storage against Enterobacteria (A), Lactic acid bacteria (B), Aerobic mesophilic bacteria (C), and Yeast (D). The asterisks indicate the values significantly different at p < 0.05 from those obtained with unwrapped (C) or CH film-wrapped cooked ham samples in the absence of basil essential oil MC.

Figure 9

pH increase in cooked ham samples unwrapped (control, C) and wrapped with films of chitosan (CH) alone or with CH films containing different concentrations of basil essential oil microcapsules (MC) at different times of storage. The asterisks indicate the values significantly different at p < 0.05 from those obtained with unwrapped (C) or CH film wrapped cooked ham samples in the absence of MC.