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Öğe Antibacterial effectiveness of chitosan-propolis coated polypropylene films against foodborne pathogens(2013) Torlak E.; Sert D.Antibacterial properties of chitosan are well documented in the literature. However its antibacterial effectiveness in the film form is controversial due to the methodological differences in test methods used. In this study, antibacterial effectiveness of chitosan-coated polypropylene films alone and incorporating ethanolic extract of propolis (EEP) were evaluated against six foodborne pathogens (Bacillus cereus, Cronobacter sakazakii, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium and Staphylococcus aureus) using the ISO 22196 method designed for the antibacterial treated plastic products. The results demonstrated that chitosan coated film exhibited the broad-spectrum antibacterial activity. Incorporation of EPP to coating at 10% (propolis resin/chitosan) enhanced antibacterial activity against all pathogens tested. Results of this study revealed that chitosan has antibacterial activity in the film form and that propolis is a promising antimicrobial for the food packaging applications. © 2013 Elsevier B.V.Öğe Characterization of lactic acid bacteria from yogurt-like product fermented with pine cone and determination of their role on physicochemical, textural and microbiological properties of product(Academic Press, 2017) Sert D.; Mercan E.; Dertli E.The aim of this study was to understand how pine cone (PC) addition could acidify the milk and result in the production of yogurt. For this purpose, yogurts were produced with three different pine cones which were classified according to collection period; PC-1 (October), PC-2 (November) and PC-3 (December). Physicochemical, textural and microbiological properties were determined as quality criteria on the yogurt samples. Importantly, Lactic Acid Bacteria (LAB) were isolated and identified from yogurt samples. 26 of 80 yogurt isolates were identified. The incubation time of yogurts until the pH reached 4.6–4.7 was ?3.5–4 h at 45 °C. Textural properties of yogurt PC-3 increased as compared to PC-1 and PC-2 which was found to be related with high LAB numbers in PC-3. Similarly, the highest dry matter, water holding capacity, acidity values were determined in the yogurt PC-3 whereas PC-1 had the lowest values. The lowest pH value was found in yogurt PC-3 related to LAB counts. Lactobacillus spp. and Streptococcus spp. counts of yogurts ranged between 5.95-6.82 and 6.32–6.99 log cfu/g, respectively. Also, LAB species were identified as Streptococcus thermophilus and Lactobacillus plantarum in all yogurt samples showing that pine cones somehow harbour the yogurt starters. © 2016 Elsevier LtdÖğe Effects of milk somatic cell counts on some physicochemical and functional characteristics of skim and whole milk powders(Elsevier Inc., 2016) Sert D.; Mercan E.; Aydemir S.; Civelek M.The aim of this work was to study the influence of milk somatic cell count (SCC) levels on spray-dried milk powders. For this reason, 3 cow milks with different SCC (<300,000, 300,000-700,000, >700,000 SCC/mL) were processed into skim (SMP) and whole milk powder (WMP). The effect of SCC on the physicochemical and functional characteristics of the milk powders and textural properties of set-type yogurts produced from reconstituted milk powders with different SCC was evaluated. A crucial difference was noted between milk powders depending on different SCC. Protein values and ash content of powder samples decreased correlatively with increasing SCC. The hydroxymethylfurfural content of SMP was higher than WMP. We noted an increase in hydroxymethylfurfural content of both SMP and WMP depending on elevated SCC. Solubility index of SMP and WMP was 1.280 to 1.632 and 0.940 to 1.208 mL, respectively; with increasing SCC, solubility index was affected adversely. The highest foam stability was determined in SMP containing >700,000 SCC. Bulk density of SMP and WMP was between 0.682 and 0.708 and 0.660 to 0.685 g/cm3, respectively. An increase was observed in scorched particle of both SMP and WMP depending on increasing SCC. We found significant differences in particle size distribution of milk powders produced from milk with SCC at different levels. Although WMP had more uniform and big particle structure, SMP had more specific area. A negative correlation was noted between yogurt texture and SCC. Results indicate that milk SCC has negative influences on milk powder quality. © 2016 American Dairy Science Association.Öğe Fate of Salmonella during sesame seeds roasting and storage of tahini(Elsevier B.V., 2013) Torlak E.; Sert D.; Serin P.Tahini is usually consumed without further heat treatment, and roasting of sesame seeds is the only Salmonella inactivation step in its traditional production process. This study examined the efficiency of the roasting process in the elimination of Salmonella from sesame seeds and the survival of Salmonella in tahini during storage. Sesame seed and tahini samples were inoculated with a cocktail of three serotypes of Salmonella (S. Typhimurium, S. Newport and S. Montevideo). Complete inactivation of Salmonella in sesame seeds, inoculated with 5.9log cfu/g, was achieved by roasting at 110°C for 60min, 130°C for 50min, or 150°C for 30min. Salmonella levels in tahini (aw=0.17) inoculated with 5.6log cfu/g and stored for 16weeks at 22 or 4°C decreased by 4.5 and 3.3 log, respectively. Results of this study demonstrated that the standard roasting process is sufficient to inactivate Salmonella in sesame seeds and low water activity of tahini prevents microbial growth, but its composition allows Salmonella to survive for at least 16weeks. Therefore, prevention of cross-contamination after roasting is crucial for food safety. © 2013 Elsevier B.V..Öğe Functional properties of tarhana enriched with whey concentrate(Eesti Pollumajandusulikool, 2015) Ertaş N.; Sert D.; Demir M.K.Whey concentrate is often sold as a nutritional supplement and include proteins, minerals, vitamins and other components (low levels of fat and low levels of lactose). Whey concentrates is well known for their high nutritional value and versatile functional properties in food products. The aim of this study was to enrich tarhana by using whey concentrate (WC) instead of yoghurt. Foaming capacity and foam stability, water and oil absorption capacity, emulsifying activity as a functional properties, colour properties and sweetness, body-texture, colour-appearance, mouthfeel, acerbity, homogeneity, consistency and overall acceptability as a sensorial characteristics of tarhana samples were determined. The highest foaming capacity values were obtained with 50% WC substitution, but 50% WC addition gave the lowest foam stability values. Oil absorption capacity and emulsifying activity values of tarhana samples were decreased by increasing WC levels. Tarhana samples containing WC were lighter according to colour values than the control tarhana samples made with yoghurt. Tarhana soup prepared with 12.5% WC addition was similar to the control in homogeneity and overall acceptability. © 2015, Eesti Pollumajandusulikool. All rights reserved.Öğe Production of skim milk powder by spray-drying from transglutaminase treated milk concentrates: Effects on physicochemical, powder flow, thermal and microstructural characteristics(Elsevier Ltd, 2019) Er B.; Sert D.; Mercan E.The effects of transglutaminase (TGase) treatment of skim milk concentrates on physicochemical, powder flow, thermal, microstructural characteristics and protein profiles of skim milk powders (SMP) were investigated. Spray-dried SMP samples produced from milk concentrates were TGase-treated at enzyme concentrations of 0 (control), 0.020% (TG-20), 0.030% (TG-30) and 0.035% (TG-35). Lower particle size values were observed in TGase-treated samples. TGase treatment slightly decreased zeta potential and increased the a* value (redness) of SMPs. Up to a concentration of 0.030%, TGase treatment decreased caking characteristics and increased glass transition temperatures of samples. The TGase treatment above 0.035% significantly decreased cohesion index and compaction coefficient at different speeds. TG-35 showed free flowing flow behaviour depending on the cohesion index, whereas control, TG-20, and TG-30 showed easy flowing behaviour. SDS-PAGE analysis revealed that high molecular mass bands indicated cross-linking in TGase-treated milk powders. © 2019 Elsevier LtdÖğe Rheological, physical and sensorial evaluation of cookies supplemented with dairy powders(SAGE Publications Inc., 2016) Sert D.; Demir M.K.; Ertaş N.The effect of dairy powders (skim milk powder, butter milk powder, sodium caseinate, yoghurt powder, milk powder and colostrum powder) on cookie quality was studied. Cookies were tested for aw, calorimetric energy, diameter, thickness, spread ratio, breaking strength, colour, dough consistency and sensory evaluation. The lowest aw values were obtained for cookies containing colostrum powder; also the highest calorimetric energy values were obtained from the colostrum powder-added cookies. Diameter values of cookies with the addition of skim milk powder, butter milk powder, yoghurt powder and milk powder were higher than that of sodium caseinate and colostrum powder. The lowest spread ratio was measured in the cookie samples with added skim milk powder. The addition of yoghurt powder gave the highest breaking strength of cookies. Cookies with sodium caseinate addition exhibited the highest lightness (L?) values than the other cookies with different dairy powders. Cookies prepared with butter milk powder received the highest scores for colour, appearance, texture, crispness and overall acceptability. © SAGE Publications.
