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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 Determination of powder flow properties of skim milk powder produced from high-pressure homogenization treated milk concentrates during storage(Academic Press, 2018) Mercan E.; Sert D.; Akın N.The aim of this study was to determine effects of high-pressure homogenization (HPH) treatment to milk concentrates on powder flow properties of skim milk powders (SMP). For this purpose, SMP samples were produced from skim milk concentrates which were HPH treated at 0 (control), 50, 100 and 150 MPa. SMP samples were stored 180 days at 20 and 40 °C and caking, cohesion and powder flow speed dependency test (PFSD) were performed using a Powder Flow Analyzer. HPH treatment decreased cohesion and caking properties of SMPs. At the 0. day, cake strength of SMPs from HPH treated concentrates varied from 0.43-2.70 mN.m, whereas cake strength of SMP-0 (control) was 8.20 mN.m. Cohesion index (CI) of samples ranged from 6.80-15.74 mm during storage. Based on CI, SMPs from HPH treated concentrates showed free and easy flowing flow behavior during storage at 20 and 40 °C. In addition, cohesion index at four speeds indicated that SMP from HPH treated concentrates were more flowable at even lower flow speeds then SMP-0. PFSD test verified that all SMP samples showed more free-flowing characteristics with increasing flow speeds. Flow stability of samples ranged from 0.95-1.15 and also flow stability of SMP-0 increased during storage at both 20 and 40 °C. The results revealed that HPH treatment to milk concentrates could improve powder flow properties of skim milk powders. © 2018 Elsevier LtdÖğe Effect of different levels of grapeseed (Vitis vinifera) oil addition on physicochemical, microbiological and sensory properties of set-type yoghurt(Blackwell Publishing Ltd, 2018) Mercan E.; Sert D.; Karakavuk E.; Akın N.The aim of this study was to determine the effect of different concentrations of grapeseed oil (GSO) addition (0.5%, 1% and 1.5% w/v) to yoghurt milk on survival of starter bacteria, and physicochemical, textural and sensory properties of set-type yoghurts during the 21 days of storage. Moreover, radical scavenging activity (RSA) and total phenolic content (TPC) of yoghurts were investigated. Yoghurts containing GSO exhibited significantly higher TPC and RSA as compared to control yoghurts. The results obtained from this investigation show that GSO has a potential to be used as a food supplement to improve health-promoting properties of yoghurt. © 2017 Society of Dairy TechnologyÖğe Effect of high-pressure homogenisation on viscosity, particle size and microbiological characteristics of skim and whole milk concentrates(Elsevier Ltd, 2018) Mercan E.; Sert D.; Akın N.Effect of high-pressure (HPH) homogenisation on milk concentrates were studied. Skim and whole milk concentrates were homogenised at 0–150 and 0–40 MPa, respectively, and viscosity, particle size measurement, microbiological and colour characteristics determined. Up to a pressure of 120 MPa, viscosity of HPH-treated skim milk concentrates (SMC) was proportional to HPH pressure and was lower than that of the control (0 MPa). With whole milk concentrates (WMC), HPH decreased viscosity up to a pressure of 20 MPa; above 30 MPa viscosity increased. According to a power law model, both skim and whole milk concentrates showed shear-thinning flow behaviour. HPH at pressures above 120 MPa completely inactivated the microbial load of SMC. Up to a pressure of 50 MPa, HPH decreased the mean particle size (D [3,2]) of SMC; an increasing trend of D [3,2] was observed above 70 MPa. Except at 40 MPa, HPH decreased D [3,2] values of WMC samples. © 2018 Elsevier LtdÖğe Effect of ultrasonic treatment on reduction of Esherichia coli ATCC 25922 and egg quality parameters in experimentally contaminated hens' shell eggs(2013) Sert D.; Aygun A.; Torlak E.; Mercan E.Backround: In this study, hen eggs which were experimentally contaminated with Esherichia coli ATCC 25922 were used. Contaminated eggs were washed statically (S5 to S30; 0 kHz) and by ultrasonic waves (U5 to U30; 35 kHz) for given applications of time (5, 15 and 30 min), then the eggs were stored at 22°C for 14 days. Results: Depending on the time of ultrasonic application, a significant increase in egg shell strength (P < 0.01) was recorded. The highest value of the Haugh unit (67.93, 1 day) was observed on the eggs which were washed by ultrasonic waves. Yolk width values of ultrasonic washed eggs diminished. E. coli was completely removed by 30 min of ultrasonic application. During storage E. coli growth was not detected on the eggs which were washed by ultrasonic waves except the eggs in U5 group (2.04 log CFU eggshell-1) on the first day of storage. Conclusion: Depending on the time of ultrasonic application a significant increase in egg quality parameters (shell strength, albumen height, Haugh units, and yolk height) were observed. The application of ultrasound led to a significant reduction in E. coli numbers on egg shells. © 2013 Society of Chemical Industry.Öğe 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/cm 3 , 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 Impact of exopolysaccharide production on functional properties of some Lactobacillus salivarius strains(Springer Verlag, 2015) Mercan E.; İspirli H.; Sert D.; Yılmaz M.T.; Dertli E.The aim of this work was to characterize functional properties of Lactobacillus salivarius strains isolated from chicken feces. Detection of genes responsible for exopolysaccharide (EPS) production revealed that all strains harbored a dextransucrase gene, but p-gtf gene was only detected in strain E4. Analysis of EPS production levels showed significant alterations among strains tested. Biofilm formation was found to be medium composition dependant, and there was a negative correlation with biofilm formation and EPS production. Autoaggregation properties and coaggregation of L. salivarius strains with chicken pathogens were appeared to be specific at strain level. An increment in bacterial adhesion to chicken gut explants was observed in L. salivarius strains with the reduction in EPS production levels. This study showed that strain-specific properties can determine the functional properties of L. salivarius strains, and the interference of these properties might be crucial for final selection of these strains for technological purposes. © 2015, Springer-Verlag Berlin Heidelberg.
