Enhancement of Mechanical Properties, Microstructure, and Antimicrobial Activities of Zein Films Cross-Linked Using Succinic Anhydride, Eugenol, and Citric Acid

Abstract

Zein constitutes about half of the endosperm proteins in corn. Recently, attempts have been made to utilize zein for food coatings and biodegradable materials, which require better physical properties, using chemical modification of zein. In this study, zein proteins were modified using citric acid, succinic anhydride, and eugenol as natural cross-linking agents in the wet state. The cross-linkers were added either separately or combined in increment concentrations (0.1, 0.2, 0.3, and 0.4%). The effects of those agents on the mechanical properties, microstructure, optical properties, infrared (IR) spectroscopy, and antibacterial activities of zein were investigated. The addition of cross-linking agents promoted changes in the arrangement of groups in zein film-forming particles. Regarding the film properties, incorporation of cross-linking agents into zein films prepared in ethanol resulted in two- to three-fold increases in tensile strength (TS) values. According to the Fourier-transform infrared (FTIR) spectra and Hunter parameters there were no remarkable changes in the structure and color of zein films. Transparency of zein films was decreased differentially according to the type and cross-linker concentration. The mechanical and optical properties of zein films were closely related to their microstructure. All cross-linked films showed remarkable antibacterial activities against Bacillus cereus ATCC 49064 and Salmonella enterica ATCC 25566. Food spoilage and pathogenic bacteria were affected in a film-dependent manner. Our experimental results show that even with partial cross-linking the mechanical properties and antipathogen activities of zein films were significantly improved, which would be useful for various industrial applications.

Zein-based films and their usage for controlled delivery: Origin, classes and current landscape

“…More recently, PEG400/zein cross-linked with natural cross-linking agents (such as succinic anhydride, succinic acid, citric acid or eugenol) in the wet state was shown to result in 2-3-fold increases in tensile strength of the films along with improved anti-pathogenic properties [62]. Similarly, chemical modification of zein through forming Schiff bases with phenolic aldehydes (such as cinnamaldehyde, benzaldehyde and 4-dimethylaminobenzaldehyde) led to improved mechanical properties and antibacterial activity [63].…”

Three Novel Lantibiotics, Ticins A1, A3, and A4, Have Extremely Stable Properties and Are Promising Food Biopreservatives

“…The B. cereus group contains diverse novel lanthipeptides, and recently reported lantibiotics in this group have been shown to exhibit high efficacy against certain Gram-positive pathogens (11,13). Therefore, we screened more than 100 strains (mainly B. cereus and B. thuringiensis) for antimicrobial activity against two important foodborne pathogens, B. cereus ATCC 49064 and L. monocytogenes LM201 (14,15), and tested the stability of the cell-free supernatant of antimicrobial-producing strains under high-temperature, strong-acid, and strong-base conditions. More than 50% of the strains exhibited antimicrobial activity against one of the indicator organisms.…”

“…For each strain, the antimicrobial activity of the cell-free supernatant (from the exponential growth phase and the stationary growth phase) was tested against two important foodborne pathogens, B. cereus ATCC 49064 and L. monocytogenes LM201 (14,15). Then we tested the stability of the cell-free supernatant of antimicrobialproducing strains at a high temperature (100°C for 30 min) and under strong-acid (pH 2.0 for 24 h) and strong-base (pH 9.0 for 24 h) conditions.…”

Stability of zein‐based films and their mechanism of change during storage at different temperatures and relative humidity

“…Plasticizers are usually added to modify the mechanical properties of films, and glycerol and PEG are the most widely used plasticizers (Ghanbarzadeh et al, 2007;Huo et al, 2018;Sothornvit & Krochta, 2005;Vieira, Silva, Santos, & Beppu, 2011). Compositing and cross-linking have been made to improve the tensile strength, elongation at break, and other properties of zein films (Cho, Lee, & Rhee, 2010;Deng, Li, Feng, & Zhang, 2019;Ghanbarzadeh & Oromiehi, 2008;Giteru, Ali, & Oey, 2019;Khalil, Deraz, Elrahman, & El-Fawal, 2015;Li et al, 2018;Mushtaq, Gani, Gani, Punoo, & Masoodi, 2018;Turasan, Barber, Malm, & Kokini, 2018;Wihodo & Moraru, 2013).…”