Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 11Citation - Scopus: 9Quantification of Staphylococcus Aureus in White Cheese by the Improved Dna Extraction Strategy Combined With Taqman and Lna Probe-Based Qpcr(Elsevier Ltd., 2014) Kadiroğlu, Pınar; Korel, Figen; Ceylan, ÇağatayFour different bacterial DNA extraction strategies and two different qPCR probe chemistries were studied for detection of Stapylococcus aureus from white cheeses. Method employing trypsin treatment followed by a commercial kit application and TaqMan probe-based qPCR was the most sensitive one detecting higher counts than standards in naturally contaminated samples.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: 66Citation - Scopus: 81Effect of Biopolymers Containing Natamycin Against Aspergillus Niger and Penicillium Roquefortii on Fresh Kashar Cheese(John Wiley and Sons Inc., 2011) Türe, Hasan; Eroğlu, Erdal; Özen, Banu; Soyer, FerdaFungal spoilage during refrigerated storage is one of the main safety and quality-related problems for dairy products. The effect of wheat gluten (WG) and methyl cellulose (MC) biopolymers containing natamycin (NA) on the growth of Aspergillus niger and Penicillium roquefortii on the surface of fresh kashar cheese during storage at 10 C for 30 days was investigated. Wrapping of A. niger-inoculated cheese with MC films containing 5–20 mg NA per 10 g resulted in approximately 2-log reductions in spore count. Two mg NA per 10 g included into WG films was sufficient to eliminate A. niger on the surface of cheese. However, MC and WG films containing NA did not cause any significant decrease in P. roquefortii count on the cheese surface. Therefore, especially use WG films in dairy applications could be an effective way of controlling A. niger growth on these products.Article Citation - WoS: 46Citation - Scopus: 53Extracellular Enzyme Production and Enterotoxigenic Gene Profiles of Bacillus Cereus and Bacillus Thuringiensis Strains Isolated From Cheese in Turkey(Elsevier Ltd., 2009) Molva, Çelenk; Sudağıdan, Mert; Okuklu, BurcuThe aim of the present study was to investigate the biochemical characteristics, extracellular enzyme production and enterotoxigenic genes contents of 6 Bacillus cereus and 22 Bacillus thuringiensis strains, isolated from 100 cheese samples in Turkey. Crystal morphologies of B. thuringiensis strains were found either spherical (n = 12) or spherical and irregular-shaped (n = 10) by phase contrast microscopy. B. cereus and B. thuringiensis strains were found to produce extracellular enzymes, respectively: gelatinase (83% and 91%), DNase (83% and 77%), lecithinase (83% and 95%), protease on skim milk agar (100% and 100%), protease on milk agar (100% and 91%), protease on casein agar (83% and 77%), xylanase (100% and 45%), and cellulase (0% and 41%), and amylase (83% and 27%). All of the strains, except for Bt-D1, hydrolyzed Tween 20 (96%), but not Tween 80 or tributyrin. Pectinolytic activity was obtained to be the least frequent (4%). PCR analysis showed that all strains contained nheA, nheB, nheC and hblD genes. The hblA and hblC genes were present in 2 and 4 of B. thuringiensis strains, respectively. The bceT gene was detected in 1 B. cereus and 9 B. thuringiensis strains. The entFM gene was detected more frequently in B. thuringiensis (82%) than in B. cereus strains (50%). To our knowledge, this is the first report about the isolation and identification of enterotoxigenic B. cereus and B. thuringiensis strains from cheese samples in Turkey.
