Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 19Citation - Scopus: 20Transparent Pullulan/Mica Nanocomposite Coatings With Outstanding Oxygen Barrier Properties(MDPI Multidisciplinary Digital Publishing Institute, 2017) Uysal Ünalan, İlke; Boyacı, Derya; Trabattoni, Silvia; Tavazzi, Silvia; Farris, StefanoThis study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α), at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount of mica (0.02 wt %, which is φ ≈ 0.00008) in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, however, this performance was partly lost as the environmental relative humidity (RH) increased. This outcome was explained in terms of the perturbation of the spatial ordering of mica sheets within the main pullulan phase, because of RH fluctuations. This was confirmed by modelling of the experimental oxygen transmission rate (OTR) data according to Cussler’s model. The presence of the synthetic nanobuilding block (NBB) led to a decrease in both static and kinetic coefficients of friction, compared with neat PET (≈12% and 23%, respectively) and PET coated with unloaded pullulan (≈26% reduction in both coefficients). In spite of the presence of the filler, all of the coating formulations did not significantly impair the overall optical properties of the final material, which exhibited haze values below 3% and transmittance above 85%. The only exception to this was represented by the formulation with the highest loading of mica (1.5 wt %, which is φ ≈ 0.01). These findings revealed, for the first time, the potential of the NBB mica to produce nanocomposite coatings in combination with biopolymers for the generation of new functional features, such as transparent high oxygen barrier materials.Article Citation - WoS: 24Citation - Scopus: 23Graphene Oxide Bionanocomposite Coatings With High Oxygen Barrier Properties(MDPI Multidisciplinary Digital Publishing Institute, 2016) Uysal Ünalan, İlke; Boyacı, Derya; Ghaani, Masoud; Trabattoni, Silvia; Farris, StefanoIn this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate) (PET) with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO) were used as main polymer phase and nanobuilding block (NBB), respectively. The oxygen barrier performance was investigated at different filler volume fractions (φ) and as a function of different relative humidity (RH) values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL m-2 24 h-1) value below the detection limit of the instrument (0.01 mL m-2 24 h-1) was recorded, even for ' as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films). Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (φ 0.03). The mechanisms underlying the experimental observations are discussed.Article Citation - WoS: 80Citation - Scopus: 107Application of Active Zein-Based Films With Controlled Release Properties To Control Listeria Monocytogenes Growth and Lipid Oxidation in Fresh Kashar Cheese(Elsevier Ltd., 2013) Uysal Ünalan, İlke; Arcan, İskender; Korel, Figen; Yemenicioğlu, AhmetThe antimicrobial and antioxidant potential of zein and zein-wax composite films having different release profiles for lysozyme and mixture of lysozyme, catechin and gallic acid were tested on cold-stored fresh Kashar cheese inoculated with Listeria monocytogenes ATCC 7644. All lysozyme containing films prevented the increase of L. monocytogenes counts in Kashar cheese for 8 weeks at 4°C, but it was only the zein-wax composite films with sustained lysozyme-release rates which caused a significant reduction (- 0.4 decimals) in initial microbial load of inoculated cheese samples. The mixture of catechin and gallic acid improved the in vitro antimicrobial effect of films against L. monocytogenes, but showed no considerable antimicrobial effect in cheese. However, the films containing catechin and gallic acid were effective in preventing oxidative changes in cheese. This study showed the possibility of increasing safety and quality of fresh cheeses by use of active packaging employing natural antimicrobial compounds and controlled release technology. Industrial relevance There has been a growing interest to develop the functional properties of packaging materials and to obtain packed foods with better shelf-life and quality. Active packaging incorporating antimicrobials is one of the most promising areas since application of this method can improve safety of foods by inhibiting pathogenic bacteria or controlling spoilage flora by using minimum amounts of active compounds. Recently, health concerns of consumers and environmental problems related to plastics increased the popularity of using natural antimicrobial substances in edible films and coatings. This work employs a GRAS status natural antimicrobial lysozyme and zein a major by-product of rapidly growing oil and bioethanol industries which can form self-standing films, coatings or casings. The results of this study showed the possibility of using flexible antimicrobial and antioxidant films with controlled release properties in diary industry.Article Citation - WoS: 48Citation - Scopus: 64Active Packaging of Ground Beef Patties by Edible Zein Films Incorporated With Partially Purified Lysozyme and Na 2edta(John Wiley and Sons Inc., 2011) Uysal Ünalan, İlke; Korel, Figen; Yemencioğlu, AhmetIn this study, antimicrobial activity of zein films incorporated with partially purified lysozyme and disodium ethylenediaminetetraacetic acid (Na 2EDTA) has been tested on selected pathogenic bacteria and refrigerated ground beef patties. The developed films containing 700μgcm -2 lysozyme and 300μgcm -2 Na 2EDTA showed antimicrobial activity on Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhimurium. The application of lysozyme and Na 2EDTA incorporated zein films on beef patties significantly decreased total viable counts (TVC) and total coliform counts after 5days of storage compared to those of control patties (P<0.05). Zein films incorporated with lysozyme and Na 2EDTA or Na 2EDTA alone significantly slowed down the oxidative changes in patties during storage (P<0.05). Redness indices of patties coated with zein films were significantly lower than those of uncoated control patties during storage (P<0.05). This study demonstrated the potential usage of zein films containing lysozyme and Na 2EDTA for active packaging of refrigerated meat products. © 2011 The Authors. International Journal of Food Science and Technology.Article Citation - WoS: 20Citation - Scopus: 23Antimicrobial Potential of Polylysine in Edible Films(Japanese Society for Food Science and Technology, 2011) Uysal Ünalan, İlke; Arserim Uçar, Dılhun Keriman; Arcan, İskender; Korel, Figen; Yemenicioğlu, AhmetThe antimicrobial activity of edible films from whey proteins, alginate, zein and chitosan incorporated with polylysine (PL) and PL- ethylenediaminetetraacetic acid (Na 2EDTA) combination have been tested on different bacteria including Escherichia coli, Listeria innocua, Salmonella Typhimurium and Stapylococcus aureus. The PL-containing films of whey proteins, alginate and chitosan were effective on L. innocua, but had limited effect on E. coli. On the other hand, the PL-containing zein films showed good antimicrobial activity on both E. coli and L. innocua as well as on S. aureus. PL-Na 2EDTA combination also gave zein films effective on S. Typhimurium. The incorporation of PL alone or PL-Na 2EDTA combination did not cause any significant change in mechanical properties of zein films. Zein has a good potential to develop novel antimicrobial packaging materials incorporated with PL.