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Resistance of Shiga toxin-producing Escherichia coli (STEC) O157:H7 and serogroups O103, O26 and O145 to synthetic gastric fluid (SGF, pH 1.5) were investigated during frankfurter storage. Pathogens were inoculated (5 ± 1 log10 cfu g-1) on frankfurters and frankfurters were stored at 4 °C for 75 days in vacuum packages. Population changes of the competitive flora and STEC, changes in the pH of the frankfurters and resistance of STEC to SGF were monitored on days 0, 15, 30, 45, 60 and 75 of frankfurter storage. Direct synthetic gastric fluid (DSGF) challenges were also conducted to assess pathogen resistance without being effected by frankfurters, by inoculating pathogen cultures directly into SGF. Results showed that acid resistance of O145 and O26 was stronger than that of O103 and O157 during frankfurter storage. Resistance of O103 to SGF was better than that of O157 during frankfurter storage but, was similar to that of O157 during DSGF challenges. Results indicate that acid resistance of some strains of STEC pathogens might differentiate during storage of frankfurters. Different resistance capabilities to SGF were observed in the STEC strains when inoculated and stored on frankfurters than directly inoculated in the SGF.

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Poly(methyl methacrylate-glycidyl methacrylate) [Poly(MMA-GMA)] cryogels were synthesized using monomers of methylmethacrylic acid and epoxy group bearing GMA via radical cryopolymerization technique. Synthesized cryogels were used for the immobilization of amyloglucosidase to the cryogel surface using epoxy chemistry. Characterizations of the free and immobilized amyloglucosidase were carried out by comparing the optimum and kinetic parameters of enzymes. For this, pH and temperature profiles of free and immobilized preparation were studied and, it was found that, optimum pH of enzyme was not change upon immobilization (pH 5.0), while optimum temperature of the enzyme shifted 10 °C to warmer region after immobilization (optimum temperatures for free and immobilized enzyme were 55 and 65 °C, respectively). Kinetic parameters of free and immobilized enzyme were also investigated and Km values of free and immobilized amyloglucosidase were found to be 2.743 and 0.865 mg/mL, respectively. Vmax of immobilized amyloglucosidase was found to be (0.496 µmol/min) about four times less than that of free enzyme (2.020 µmol/min). Storage and operational stabilities of immobilized amyloglucosidase were also studied and it was showed that immobilized preparation had much more stability than free preparation. In the present work, amyloglucosidase immobilized poly(MMA-GMA) cryogels were used for continuous glucose syrup production from starch for the first time. Efficiency of immobilized enzyme was investigated and released amount of glucose was found to be 2.54 mg/mL at the end of the 5 min of hydrolysis. The results indicate that the epoxy functionalized cryogels offer a good alternative for amyloglucosidase immobilization applications with increased operational and thermal stability, and reusability. Also, these cryogels can be used for immobilization of other industrially valuable enzymes beyond amyloglucosidase.

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The fatty acids of six wild edible mushroom species (Boletus reticulatus, Flammulina velutipes var. velutipes, Lactarius salmonicolor, Pleurotus ostreatus, Polyporus squamosus, and Russula anthracina) collected from different regions from Anatolia were determined. The fatty acids were identified and quantified by gas chromatography and studied using fruit bodies. Fatty acid composition varied among species. The dominant fatty acid in fruit bodies of all mushrooms was cis-linoleic acid (18 : 2). Percentage of cis-linoleic acid in species varied from 22.39% to 65.29%. The other major fatty acids were, respectively, cis-oleic, palmitic, and stearic acids. Fatty acids analysis of the mushrooms showed that the unsaturated fatty acids were at higher concentrations than saturated fatty acids.

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The chemical, microbiological and sensory properties of doners produced by traditional or continuous processes were investigated. The production method (traditional or continuous) did not affect microbiological quality (p < 0.05). Doners produced by traditional process had generally better sensory properties than those produced by continuous process. Continuous process produced turkey meat doners with lesser fat content (p < 0.05), higher moisture content (p < 0.05). Even though, doners produced by the traditional process were given higher ratings by the sensory panel than those produced by the continuous process, the difference might not have any practical importance. Given the higher production capacity, continuous process is expected to replace traditional process in the years to come.

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The aim of this research was to determine the changes in chemical and microbiological qualities of ready-to-eat intermediate-moisture raisins during storage. Raisins were immersed into hot (98+/-1 degrees C) glucose solutions (10% w/v and 20% w/v) containing 1% (w/v) potassium sorbate to inhibit mould and yeast growth. Raisins were kept in glucose solutions until the moisture content became 20%, 25% and 30%, respectively. The reconstituted raisins were then stored at ambient temperature (23+/-3 degrees C) and 50-60% relative humidity for 8 months in polyethylene/polyamide (PE/PA) packaging material. The changes of moisture content, water activity, pH values, total titratable acidity, total sugar contents, Hunter L, a and b color values, total mesophylic aerobic bacteria counts, and mould and yeast counts were determined during storage at 2-month intervals. The results of chemical analysis showed that changes in the total titratable acidity, total mesophylic aerobic bacteria, and mould and yeast counts of the products were increased significantly (P<0.05). However, the pH values, total sugar contents, and Hunter L, a, and b color values were decreased during the storage period (P<0.05).

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