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    ANTIMICROBIALS USED IN ACTIVE PACKAGING FILMS
    (2018) Dıblan, Sevgin; Kaya, Sevim
    Active packaging technology is one of the innovative methods for preserving of food products, and antimicrobial packaging films is a major branch and promising application of this technology. In order to control microbial spoilage and also contamination of pathogen onto processed or fresh food, antimicrobial agent(s) is/are incorporated into food packaging structure. Polymer type as a carrier of antimicrobial can be petroleumbased plastic or biopolymer: because of environmental concerns researchers have lean to development of biodegradable antimicrobial films. Antimicrobial substances can be organic acids, parabens, sulfites, nitrites, phosphates, alcohols, antibiotics and bacteriocins. Succeed of antimicrobial film mainly depends on antimicrobial agent selection that antimicrobial should be chosen according to the food type packed, and deteriorative microbial flora of it. This review discussed the recent application of antimicrobial-active films for food protection. Also, their activity mechanisms against microorganisms, the effects of antimicrobials on food quality and of the film properties were presented
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    Development and structural assessment of whey protein isolate/sunflower seed oil biocomposite film
    (Elsevier, 2019) Erdem, Burcu Gokkaya; Diblan, Sevgin; Kaya, Sevim
    The overall aim of this research was to investigate effect of sunflower oil addition on formation of whey protein based biocomposite edible films. The biocomposite films were prepared through an emulsion technique by dispersing three different ratios of sunflower oil (0.05%, 0.10% and 0.15%) in whey protein isolate medium. Moisture content, solubility in water, water sorption kinetic, swelling index, contact angle, color, whiteness, and opacity index of the films were examined. Thermal, barrier, and mechanical properties were tested. Particle size distribution and surface microstructure of the films were also analyzed. The moisture content of the biocomposite films was not affected with sunflower oil addition but the solubility showed reducing tendency. Increasing oil content increased contact angle. Although color parameters, whiteness index, and total color were not affected significantly by oil addition whereas the opacity index of the biocomposite films was determined to be higher than the control film (no sunflower oil present). Glass transition value of the control film was significantly lower than those of emulsified films (p <0.05). All of the film forming emulsions showed bimodal particle size distribution with two major peaks. The results showed that despite the low oil amount in biocomposite film composition, oil addition had a positive effect on the water vapor and oxygen barrier properties of the films. It was understood that low amount of sunflower oil increased the hydrophobic property of the films without any adverse change in the barrier and optical characters of the films. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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    Potassium sorbate diffusion in multilayer polymer films: Effects of water activity and pH
    (Wiley, 2018) Diblan, Sevgin; Kaya, Sevim
    The main aim of this study was to estimate the effect of acidity and water activity (a(w)) on the diffusion of potassium sorbate (PS) into model aqueous systems at 25 degrees C from an industrially produced multilayer active film (LPDE/polyamide/LPDE containing 2%PS). The releases of PS from films were set according to two factors face-centered central composite design of the response surface method (RSM). The ANOVA, 3D response surface, and 2D contour plots showed that pH and a(w) were effective factors in the diffusion coefficient (D) of PS from the films, and these two variables had an important interaction between them. Film samples within the liquid medium with low a(w) and pH values had the highest D. This might have occurred owing to the swelling of films within the solution with lower a(w) and high solubility of PS, and within the solution having lower pH, the faster diffusion of PS might have occurred. Practical applicationsIn this study, the diffusion kinetic of potassium sorbate was observed under various conditions, such as pH and water activity. These conditions are the most important physico-chemical properties for food products. Moreover, the efficiency of the sorbate depends on the pH of the medium; with increasing pH, the efficiency is decreased, and above pH=6.5, sorbic acid loses its antimicrobial property. Thus, the pH level is very important for the application of such films. Furthermore, these properties can affect both food product specialists and antimicrobial agent release. The pH and water activity were found to be very effective in diffusion kinetics of potassium sorbate. The results showed that antimicrobial diffusion from an active packaging film should be evaluated according to the food properties. We also observed adverse changes in the film structure, especially at lower water activity values. It was possible to relate the effect of a(w) on diffusion with the characteristics of film, the incorporated agents, and the used system. Depending on the diffusion medium, the film structure might change, and this could accelerate or limit the migration.
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    Sorption, diffusivity, permeability and mechanical properties of chitosan, potassium sorbate, or nisin incorporated active polymer films
    (Springer India, 2020) Diblan, Sevgin; Erdem, Burcu Gokkaya; Kaya, Sevim
    The active multilayer packaging films were formed from low-density polyethylene (LDPE) and polyamide containing a 2% antimicrobial agent in one of the LDPE sides of the film (LDPE/polyamide/LDPE-2% antimicrobial agent). The antimicrobial agents used were potassium sorbate (PS-film), nisin (N-film), or chitosan (CTS-film). The effects of antimicrobial incorporation on water vapor permeability (P), diffusivity (D-eff), and solubility (S-o and S-H) of the active and control films (LDPE/polyamide/LDPE) were investigated. A dynamic vapor sorption analyzer (DVS) was used to estimate the sorption isotherms of the films at 25 degrees C. Peleg was found to be the best equation to describe sorption behaviors. The addition of PS and nisin into the film matrix resulted in a lower P than that of the control film. The D-eff values of the active films were lower than those of control films, except for the CTS-film. The high water-holding capacity of PS and nisin might limit the D-eff of the respective films. It was found that Henry's law was applicable to relate P, D-eff, and S-o and S-H values of the multilayer film [correlation coefficient (r) = 0.909-0.971]. The mechanical and thermal properties of the active films were not significantly affected by the incorporation of PS and nisin (p > 0.05). However, the impact of stress and elongation (transverse direction) on the CTS-film was lower than on other films, which indicated that chitosan improved the mechanical properties of the film.