Abstract
The effects of heat treatment and the addition of tarragon essential oil on physical and mechanical properties of films prepared with 5% whey-protein isolate (WPI) and 5% glycerol were investigated in this study. Heat-treatment of the film-forming solution caused increases in thickness, moisture content, swelling degree, water vapor permeability (WVP), b*-value, ΔE*-value, transmittance values in the 200–300 nm region, transparency, and puncture resistance of the film, but decreases in water solubility, L*-value, a*-value, transmittance values in the 350–800 nm region, and puncture deformation. When incorporated with tarragon essential oil, heat-treated films have the potential to be used as antimicrobial food packaging. The addition of tarragon essential oil in film-forming solution caused increases in moisture content, solubility in water, WVP, a*-value, b*-value, ΔE*-value, and transparency of the film, and decreases in L*-value, and transmittance values in the range of 600–800 nm. It also caused variations in swelling degree, transmittance values in the range of 300–550 nm, puncture resistance, and puncture deformation. Nevertheless, different tendencies were noticed in UNT and HT films in terms of transparency, light transmittance, puncture resistance, and puncture deformation. Based on these findings, HT films show improved physical and mechanical properties; therefore, they are more suitable for food-packaging applications.
Supplementary Materials
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/Foods2021-11197/s1.
Author Contributions
Conceptualization, C.A.S. and D.C.V.; methodology, C.A.S. and D.C.V.; formal analysis, M.-I.S., M.F., S.A.S., A.S.P. and V.M.; writing—original draft preparation, M.-I.S.; writing—review and editing, C.A.S.; visualization, D.C.V.; supervision, C.A.S. and D.C.V.; project administration, C.A.S. and D.C.V.; funding acquisition, D.C.V. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by a grant from the Ministry of Research and Innovation, as follows: CNCS-UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-0056, 2 PCCDI within PNCDI III; and the publication was supported by funds from the National Research Development Projects to finance excellence (PFE)-37/2018-2020 granted by the Romanian Ministry of Research and Innovation.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
We are grateful for the administrative and financial support received from the University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Romania.
Conflicts of Interest
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).