Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 5Citation - Scopus: 5Physicochemical and Active Properties of Gelatine-Based Composite Gels Loaded With Lysozyme and Green Tea Polyphenols(University of Zagreb, 2021) Boyacı, Derya; Barış Kavur, Pelin; Güleç, Şükrü; Yemenicioğlu, AhmetResearch background. The use of gel-based systems as a novel method for the delivery of natural antimicrobial, antioxidant and bioactive compounds is a developing innovative solution for the food industry. This research aims to develop multifunctional active edible gels based on gelatine and its composites with improved mechanical properties. Experimental approach. Antilisterial and bioactive composite gels showing different physical and active properties from classical gelatine gel were developed by loading lysozyme and green tea extract into gelatine/starch and gelatine/wax composite gels. Mechanical properties, swelling profiles, colour, release profiles, and antimicrobial and bioactive properties of the gels were characterised. Results and conclusions. Gelatine/wax gels showed 1.3-to 2.1-fold higher firmness and cutting strength than gelatine and gelatine/starch composite gels that had similar firmness and cutting strengths. Work to shear of both composite gels was 1.4-to 1.9-fold higher than that of gelatine gel. The gelatine/starch gel showed the highest water absorption capacity. Green tea extract reduced soluble lysozyme in all gels, but composite gels contained higher amount of soluble lysozyme than gelatine gel. All the gels with lysozyme inhibited Listeria innocua growth in the broth media, while green tea extract showed antilisterial activity only in gelatine/wax gels. Gels with green tea extract showed antioxidant, antidiabetic (?-glucosidase and ?-amylase inhibition), antihypertensive (angiotensin-converting enzyme inhibition) and antiproliferative activities (on Caco-2 human colon carcinoma cells). However, gelatine and gelatine/wax gels showed the highest antioxidant and antidiabetic activity. The gelatine/wax gels prevented phenolic browning, while green tea extract in other gels showed moderate or extensive browning. Novelty and scientific contribution. This work clearly showed the possibility of improving mechanical properties and modifying water absorption and controlled release profiles of gelatine gels using gelatine/starch and gelatine/wax composites. The novel composite gels reduced browning of incorporated polyphenols and showed antilisterial and bioactive properties. © 2021, University of Zagreb. All rights reserved.Article Citation - WoS: 49Citation - Scopus: 55Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus Aureus Strains Isolated From Raw Milk and Cheese Samples(International Association for Food Protection, 2012) Sudağıdan, Mert; Yemenicioğlu, AhmetEffects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops. Copyright ©, International Association for Food Protection.Article Citation - WoS: 39Citation - Scopus: 49Production of Antimicrobial Films by Incorporation of Partially Purified Lysozyme Into Biodegradable Films of Crude Exopolysaccharides Obtained From Aureobasidium Pullulans Fermentation(University of Zagreb, 2005) Kandemir, Nilay; Yemenicioğlu, Ahmet; Mecitoğlu, Çiğdem; Elmacı, Zehra Seda; Arslanoğlu, Alper; Göksungur, Mehmet Yekta; Baysal, TanerAntimicrobial films were produced by incorporating partially purified lysozyme into films of crude exopolysaccharides (59% pullulan) obtained from Aureobasidium pullulans fermentation. After film making, the films containing lysozyme at 100, 260, 520 and 780 μg/cm2 showed 23 to 70% of their expected enzyme activities. The highest recovery of enzyme activity (65-70%) after the film making was obtained in films prepared by incorporating lysozyme at 260 μg/cm2 (1409 U/cm2). The incorporation of disodium EDTA·2H2O and sucrose did not affect the initial lysozyme activity of the films significantly. With or without the presence of disodium EDTA·2H2O at 52 or 520 μg/cm2, lysozyme activity showed sufficient stability in the films during 21 days of cold storage. However, the presence of sucrose at 10 mg/cm2 in the films caused the destabilization of part of enzyme activity (almost 35%) at the end of storage. The combinational incorporation of lysozyme at 780 μg/cm 2 (4227 U/cm2) and disodium EDTA·2H2O at 520 μg/cm2 gave antimicrobial films effective on Escherichia coli. However, in the studied lysozyme concentration range the films did not show any antimicrobial activity against Lactobacillus plantarum. This study clearly showed that the partially purified lysozyme and crude exopolysaccharides from Aureobasidium pullulans may be used to obtain antimicrobial films to increase the safety of foods.