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    Effects of process stages on Turkish delight/lokum microbiological quality
    (Wiley, 2014) Ipek, Dilvin; Zorba, Nukhet N. Demirel
    The sources of microbiological contamination at the lokum production lines of two local confectionaries were determined. Surface samples from the production lines were evaluated by standard and ATP bioluminescence methods. Microbial loads of raw materials were also determined. The trays and cutting knives were found to be the primary contamination sources, and personnel hands were found to be the secondary contamination sources, while all of them were found to be the secondary sources when the standard swab method was applied. Raw materials were not sources of contamination, because of their microbiological loads and the following high-temperature cooking stages. The microbial loads of lokum also were not high, due to product contents and the processes applied to lokum. There is a need for further studies related to the effects of process steps on the physical and the chemical quality of lokum. Training for workers in food safety at the confectionaries is also needed.
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    Evaluation of usage of essential oils instead of spices in meat ball formulation for controlling Salmonella spp.
    (Sage Publications Ltd, 2016) Ozdikmenli, Seda; Zorba, Nukhet N. Demirel
    The purpose of this study was to show the efficacy of essential oils (EOs) in meat balls instead of spices because of their high antimicrobial effect and to evaluate the antimicrobial effect of Origanum onites and Ocimum basilicum EOs against Salmonella Typhimurium in minced beef (20% fat) stored at 4? for seven days. This is the first study about use of O. basilicum EO in minced beef against bacterial pathogens. Both EOs inhibit microorganisms in invitro antibacterial tests. Minimum inhibitory concentration (MIC) values of EOs were determined. The lowest MIC values were obtained with O. onites EO 0.6 mu l/ml against S. Typhimurium strains. The MIC values of O. basilicum EO 0.25 mu l/ml against microorganisms. Both EOs showed a significant decrease in microorganisms inoculated in minced beef at end of storage. The concentration of the both EOs at 20 mu g/mg and 10 mu g/mg showed stronger antimicrobial activity against bacterial cocktail of S. Typhimurium in beef; however, the higher concentrations caused alterations in the organoleptic properties of meatballs. The results of the present study indicate that O. onites and O. basilicum EOs may be used in combination with each other and different food preservation systems in meat ball formulation.
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    Frequency of extended-spectrum ?-lactamase (ESBL)- and AmpC ?-lactamase-producing Enterobacteriaceae in a cheese production process
    (Elsevier Science Inc, 2018) Tepeli, Seda Ozdikmenli; Zorba, Nukhet N. Demirel
    The aim of this study was to investigate the extended-spectrum beta-lactamase (ESBL) and AmpC beta-lactamase activities of Enterobacteriaceae isolated from raw milk and cheese production line and to determine the probability of transmitting these bacteria to consumers. One hundred seventy-three samples from raw milk and cheese production lines were analyzed; 64 isolates were confirmed as Enterobacteriaceae. Sixteen of 64 isolates (25%) were resistant to at least one cephalosporin according to European Committee on Antimicrobial Susceptibility Testing Standards (EUCAST) and Clinical and Laboratory Standards Institute criteria. Seven of the 16 resistant isolates (43.75%) had confirmed ESBL activity. Additionally, phenotypic AmpC beta-lactamase activity was observed in 31 (48.44%) of 64 Enterobacteriaceae isolates and confirmed in 27 of the 31 strains (89.1%). Overall, 3 isolates showed both ESBL activity and AmpC resistance, 28 isolates were only AmpC resistant, and 5 isolates had ESBL activity alone. Of the 173 samples, the proportions of samples that contained ESBL- and AmpC-producing isolates were 4.64 and 15.6%, respectively. Five of the ESBL-positive isolates (62.5%) and 11 of the AmpC-positive isolates (40.7%) were obtained from bulk milk tanks; therefore, the bulk tank plays a very important role in the spread of antibiotic-resistant bacteria. Periodic cleaning and maintenance of bulk tanks should be performed and recorded. Effective food safety and hygiene practices should significantly reduce cross-contamination in dairy plants.
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    Microbial load of white cheese process lines after CIP and COP: A case study in Turkey
    (Elsevier Science Bv, 2018) Ipek, Dilvin; Zorba, Nukhet N. Demirel
    Microbial adhesion, contamination and biofilm formation are major problems in the dairy industry, in cheese production, and for consumer health. In our study, the microbial loads of white cheese process lines were examined after cleaning treatments. Bacillus spp. was determined as the most common species on process lines. Drainage, air, and water entry points were found as important contamination points. Biofilm forming capacity of Enterobacteriaceae as revealed using Congo Red agar, was very high. In addition, the standard counting and ATP Bioluminescence methods were applied and compared for evaluating biofilms. The ATP-Bioluminescence method was found useful for rapidly identifying the biofilm-formable surfaces.
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    Potential of antimicrobial active packaging 'containing natamycin, nisin, pomegranate and grape seed extract in chitosan coating' to extend shelf life of fresh strawberry
    (Elsevier, 2016) Duran, Merve; Aday, Mehmet Seckin; Zorba, Nukhet N. Demirel; Temizkan, Riza; Buyukcan, Mehmet Burak; Caner, Cengiz
    In this study, chitosan (CH) coatings as carrier of nisin (NS), natamycin (NT), pomegranate (PE) and grape seed extract (GE) were used to maintain quality and extend shelf life of fresh strawberry. The samples were analyzed in terms of gas composition inside packaging, pH, total soluble solid content, water activity, color, texture, FT-NIR and microbial counts for up to 40 days at 4 degrees C. The experiments showed that all coating materials preserved the quality of fresh strawberry compared to untreated ones. Among the treatments, incorporation of the natamycin in the chitosan coating (CH+NT) reduced the O-2 consumption of the fruit and showed better effects on delaying changes of pH, total soluble solid content, water activity and microbial counts. The incorporation of different antimicrobial agents into chitosan matrix did not reveal any significant effect on lightness (L*) and redness (a*) of strawberry. Among the treatments, CH + PE and CH + NT showed significantly higher antimicrobial effect against the mesophilic bacteria and yeast and mold. As a general result, antimicrobial active packaging based on the combination of chitosan coating with antimicrobial agents increased the shelf life of fresh strawberry compared to uncoated fruit. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.