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Öğe Biocontrol of Salmonella Enteritidis on chicken meat and skin using lytic SE-P3, P16, P37, and P47 bacteriophages(Elsevier, 2021) Demirarslan, Ozgul Aydin; Alasalvar, Hamza; Yildirim, ZelihaThe present study was conducted to investigate the virulent effects of SE-P3, P16, P37, and P47 phages specific to Salmonella Enteritidis, alone or as a cocktail on raw chicken meat and chicken skin. Chicken meat and skin artificially contaminated with 10(3) and 10(6) log CFU/g or cm(2) Salmonella were treated with SE-phages at a level of 10(9) PFU/g or cm(2) and then the samples were stored at 4 degrees C for 8 days and 25 degrees C for 4 days. The infective effects of SE-phages for prevention of contamination during or before contamination at 4 degrees C were also determined. SE-phages reduced the number of viable Salmonella cells in the samples containing Salmonella at 10(3) CFU/g to an undetectable level throughout storage at 4 and 25 degrees C. In samples containing 10(6) CFU/g or cm(2 )Salmonella, SE-phages decreased the number of host cells by 4.11-6.42 log CFU/g or cm(2) on the first day of storage. Furthermore, SE-phages have been found to effectively prevent subsequent Salmonella contamination at 4 C. This study showed that SE-P3, P16, P37, and P47 phages have the potency to be used as a biocontrol strategy to control Salmonella in the poultry industry.Öğe Characterization of SE-P3, P16, P37, and P47 bacteriophages infecting Salmonella Enteritidis(Wiley, 2019) Yildirim, Zeliha; Sakin, Tuba; Akcelik, Mustafa; Akcelik, NesifeThe aim of this study was to identify and characterize the SE-P3, P16, P37, and P47 phages infecting Salmonella Enteritidis. Transmission electron microscopy analysis showed that the SE phages belonged to the Myoviridae or Siphoviridae family and had plaque sizes between 0.622 +/- 0.027 and 1.630 +/- 0.036mm in diameter. sefC, pefA, spvC, sopE, and gipA virulent gene regions were absent in their genome and their calculated genome sizes were between 35.9 and 37.8 kbp. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that the protein profiles of each phage were different. The SE phages had a short latent period (10-20 min), large burst size (76-356 PFU/cell), and a short burst time (25-35 min). The multiplicity of infection values and mutant frequency of the phages were 0.01-0.0001 and 10(-7), respectively. They were very infective against their host bacteria when applied at 20 degrees C, 30 degrees C, or 37 degrees C and adsorbed to their host cells by 96.20-97.65% in the first 5 min of incubation, and also Ca2+ ions did not have a significant effect on their adsorption. The SE phages were resistant to wide pH ranges and high temperatures. These results indicate that the SE phages are good candidates as therapeutic and biocontrol agents against foodborne pathogenic S. Enteritidis.Öğe Chitosan films tailored with deep eutectic solvent extracts from Hibiscus sabdariffa: Fabrication and characterization(Elsevier B.V., 2024) Alasalvar, Hamza; Sürmeli, Hasan Nazim; Yildirim, ZelihaNatural polymers are the most promising alternatives to petroleum-based plastics for developing biodegradable food packaging films. However, the brittleness and lack of active protection of films from most natural polymers pose a challenge to their practical application. The addition of plasticizers and natural extracts to these films is considered an effective solution to address these issues. In this study, the potential for the use of deep eutectic solvents (DESs) and DES extracts derived from Hibiscus sabdariffa in the production of chitosan films and their effects on their mechanical and antioxidant properties were examined. Initially, the extraction efficacy of DESs composed of choline chloride (ChCl) and various carboxylic acids (citric, lactic, tartaric, and oxalic acids) was evaluated in terms of phenolic and anthocyanin contents along with antioxidant activities. Optimal results were achieved with the utilization of ChCl-oxalic acid as the extraction medium. Subsequently, chitosan films were fabricated by introducing DESs and DES extracts as plasticizers and compared with glycerol-plasticized chitosan films. The incorporation of DESs and DES extracts into the film matrix led to a notable reduction (11.78–14.82%) in moisture content compared with glycerol (25.34%). Notably, using ChCl-tartaric acid improved the tensile strength, while ChCl-citric acid enhanced the film flexibility. Films containing ChCl-tartaric acid demonstrated exceptional light barrier properties. SEM analysis revealed an interaction between chitosan and DESs, which was further corroborated by FTIR and XRD. Additionally, DES extracts provided superior antioxidant activity to the films than their pure DESs. These findings suggest a significant potential for DES extracts from Hibiscus sabdariffa as bioactive agents and plasticizers in chitosan films. © 2024 Elsevier B.V.Öğe Control of Listeria monocytogenes contamination in fresh beef by using lactococcin BZ(Wiley, 2017) Yildirim, Zeliha; Yerlikaya, Sabire; Oncul, NilgunThe aim of this study was to investigate the inhibitory effect of lactococcin BZ produced by Lactococcus lactis spp. lactis BZ against Listeria monocytogenes in raw beef. Lactococcin BZ depending on concentration (400-3,200 AU/ml) reduced the counts of L. monocytogenes attached to meat surface (from 4.71 log CFU/g to undetectable level, and from 7.92 to 3.64 log CFU/g) in 5 min. When meat samples were simultaneously inoculated with lactococcin BZ and L. monocytogenes, lactococcin BZ reduced the count of non-attached Listeria cells in 5 min by 1.58-5.03 (undetectable level) log cycles in the low inoculum (5.03 log CFU/g) and 1.11-5.58 log cycles in the large inoculum (7.86 log CFU/g) compared to control samples. Also, lactococcin BZ at 400-3,200 AU/ml reduced the number of L. monocytogenes in meat samples inoculated at 2.45, 4.42, and 7.29 log CFU/g throughout 12 day storage at 4 degrees C and maintained its biological activity. In addition, lactococcin BZ adsorbed to meat surface and adsorption did not adversely affected antilisterial activity. Practical applicationsIn this study, we investigated the inhibitory effect of lactococcin BZ produced by Lactococcus lactis spp. lactis BZ against Listeria monocytogenes during, after or before attachment on raw beef. It was observed that lactococcin BZ depending on its concentration (400-3,200 AU/ml) and amount level of Listeria cells (4.71 or 7.92 log CFU/g) reduced the cell counts of L. monocytogenes in the meat samples very effectively. Lactococcin BZ at 1,600 and 3,200 AU/ml showed strong antilisterial activity toward L. monocytogenes before, during and after attachment to meat samples, but its antilisterial activity was higher before or during attachment than after attachment. Therefore, lactococcin BZ could be potential alternatives to chemical preservatives for meat industry.Öğe Decontamination of Salmonella Enteritidis on Eggshell: Assessment of Efficiency of a Bacteriophage and Levulinic Acid-Sodium Dodecyl Sulfate(Sidas Medya A.S., 2024) Alasalvar, Gamze Koçer; Yildirim, ZelihaThe majority of food infections caused by consumption of egg and egg products are caused by Salmonella enterica subspecies enterica serovar Enteritidis. In this study, the inhibitory effect against S. Enteritidis was determined by dipping the eggshell into Salmonella-specific bacteriophage SE-P47 and levulinic acid (LVA) plus sodium dodecyl sulfate (SDS) solutions (0.5% LVA+0.05% SDS, 1% LVA+0.05% SDS and 2% LVA+0.5% SDS) separately for 10 minutes. The treatments of phage and 2% LVA+0.5% SDS reduced S. Enteritidis below the detectable level on eggshell (at 2.76, 3.22, 4.48 and 5.30 log CFU/cm2inoculum levels). After the treatment of 1% LVA+0.05% SDS, 1.94 and 0.89 log reductions were obtained at 4.48 and 5.30 log CFU/cm2inoculum levels, respectively, while S. Enteritidis decreased below the detectable number at 2.76, 3.22 log CFU/cm2inoculum levels. Although the lowest antibacterial activity was observed in the treatment of 0.5% LVA+%0.05 SDS, the decrease in the number of S. Enteritidis detected in all samples except 5.30 log CFU/cm2 inoculum level was found to be significant compared to the control sample. The results indicated that the combination of LVA and SDS, and especially SE-P47 phage alone had good potential efficacy for Salmonella decontamination on eggshell. © 2024 Sidas Medya A.S.. All rights reserved.Öğe Development and characterization of sustainable active pectin films: The role of choline chloride/glycerol-based natural deep eutectic solvent and lavender extracts(Cell Press, 2023) Alasalvar, Hamza; Yildirim, Zeliha; Yildirim, MetinThis study aimed to evaluate the potential effects of choline chloride: glycerol-based natural deep eutectic solvent (NADES) as a plasticizer, NADES extract (NADESext) of lavender as both plasticizer and active ingredient, as well as the lyophilized extract (LE) of lavender at different concentrations (0.5 %, 1 %, and 2 %) on the physical, mechanical, optical, thermal, barrier, morphological, and antioxidant properties of pectin films. The properties of the films were compared to those of the neat pectin film and the film plasticized with glycerol. The addition of plasticizers and LE increased thickness, water vapor permeability, and elongation at break values of the films while decreasing tensile strength and young modulus. Pectin films plasticized with glycerol, NADES, and NADESext had a similar color property but a lower opacity. The use of LE decreased lightness and increased opacity compared to the films with plasticizers. The addition of plasticizers revealed a smoother surface than neat pectin film while LE triggered the formation of agglomerates on the films. Changes in the FTIR spectra of the films showed some interactions between pectin and polyphenols in LE. The plasticizers had an insignificant effect on the antioxidant capacity of films whereas LE improved antioxidant capacity depending on the concentration. In conclusion, the results suggested that pectin films with NADES and LE could be beneficially used to improve antioxidant packaging technology along with acceptable mechanical properties.Öğe Effect of partial fat replacement by hazelnut oil microcapsules in beef burger formulations on physicochemical properties, fatty acid composition, and sensory attributes(Wiley, 2022) Alasalvar, Hamza; Alasalvar, Gamze Kocer; Yildirim, ZelihaThis study was conducted to evaluate the effects of partial use of hazelnut oil microcapsules (HOM) instead of animal fat on beef burgers. For this purpose, the burgers were prepared with the replacement levels of 10%, 25%, and 50% of animal fat by HOM. The incorporation of HOM decreased lipid content (from 13.42% to 9.23%) in the burgers. Lipid reformulation improved the fatty acid profiles. The saturated fatty acid content, atherogenic index, and thrombogenic index of burgers decreased from 43.11% to 29.69%, 0.59 to 0.33, and 1.26 to 0.73, respectively. The replacement level of 50% resulted in the lowest thiobarbituric acid reactive substances value. No changes were measured for hardness and gumminess up to the replacement level of 25%. According to these findings, the use of HOM as an animal fat substitute can enhance the nutritional and cooking characteristics and fatty acid profiles of the burgers without affecting sensory acceptability. Novelty impact statement Hazelnut oil microcapsules (HOM) were used for the first time as a fat substitute in burgers. The use of HOM improved the fatty acid profiles and decreased the lipid oxidation of burgers. Consequently, fat replacement with HOM could be an alternative approach to reduce fat content and manipulate the fatty acid profile of the burgers.Öğe Encapsulation of SE-P47 phage specific to Salmonella Enteritidis and evaluation of its stability(Wiley, 2024) Alasalvar, Gamze Kocer; Yildirim, ZelihaThis study was conducted to encapsulate the bacteriophage SE-P47 target to Salmonella Enteritidis by extrusion method and to examine its stability. Screening and optimization of effective factors in the encapsulation process were performed using fractional factorial design and face-centered central composite design, respectively. The optimum Na-alginate concentration and the ratio of coating material to phage for the encapsulation of SE-P47 phage were 1.5% (v/v) and 2:1, respectively. At the optimum encapsulation point, the highest encapsulation efficiency (98.52%), smallest capsule size (1.28 mm), and highest phage titer were achieved. When exposed to heat treatment at 80 degrees C for 30 min, pH 2 and simulated gastric fluid (pH 2.0) for 120 min, the encapsulated phage maintained almost its stability, but the free (non-encapsulated) phage almost lost its activity. Phage release from beads in simulated intestinal fluid reached 100% in 4 h. In addition, free and encapsulated phage completely maintained their activity for 12 months at 4 and 25 degrees C. The Salmonella phage encapsulated in this study exhibits high stability in harsh conditions. Thus, this encapsulated phage has the potential to be used as a biocontrol agent or therapeutic purposes in the food chain.Öğe Enterocin HZ produced by a wild Enterococcus faecium strain isolated from a traditional, starter-free pickled cheese(CAMBRIDGE UNIV PRESS, 2014) Yildirim, Zeliha; Bilgin, Harun; Isleroglu, Hilal; Tokatli, Kader; Sahingil, Didem; Yildirim, MetinBacteriogenic Enterococcus faecium HZ was identified by using biochemical (Strep-API 20, API-50 CHL, fatty acid profile) and 16S rRNA analysis (99 center dot 99%). Ent. faecium HZ was sensitive to clinically important antibiotics such as vancomycin, and did not have gelatinase and haemolysis activities. Enterocin HZ, a bacteriocin from Ent. faecium HZ, was sensitive to papain and tyripsin, but resistant to pepsin, lipase, catalase, alpha-amylase, organic solvents, detergents, ss-mercaptoethanol, and heat treatment (90 degrees C/30min). It was biologically active at pH 2 center dot 0-9 center dot 0 and synthesised at the highest level in MRS or M17 broth at 32 or 37 degrees C with an inoculum amount of 0 center dot 1-0 center dot 5% and an initial pH of 6 center dot 0-7 center dot 0. Enterocin HZ production reached maximum level at middle and late logarithmic phase and its molecular weight was similar to 4 center dot 5kDa. It was active against some Gram-positive foodborne bacteria. Ent. faecium HZ or its bacteriocin enterocin HZ is a good candidate to be studied as a food biopreservative since enterocin HZ showed strong bactericidal activity against Listeria monocytogenes in UHT milk and also Ent. faecium HZ grew very well in milk and produced enterocin HZ at maximum level.Öğe Identification and characterization of lytic bacteriophages specific to foodborne pathogenicEscherichia coliO157:H7(Sage Publications Ltd, 2021) Yildirim, Zeliha; Sakin, Tuba; Akcelik, Mustafa; Akcelik, NefiseThe objective of this study was to identify and characterize five different lytic bacteriophages specific toEscherichia coliO157:H7. vB_EcoM-P12, vB_EcoM-P13, vB_EcoM-P23, and vB_EcoM-P34 phages belonged to the Myoviridae family and vB_EcoS-P24 phage was in the Siphoviridae family. Their plaque sizes changed between 0.48 +/- 0.03 and 0.90 +/- 0.03 mm in diameter.stx1andstx2virulent gene regions were absent in the genome of five Eco-phages and their genome size was 33 kbp. The protein band profiles of the five phages were found to be different from each other. Their latent period, burst size, and burst time changed between 10-15 min, 72-144 PFU/cell and 20-35 min, respectively. Multiplicity of infection values and mutant frequency of the phages were among 0.1-0.001 and 1.14 x 10(-7)-3.69 x 10(-8), respectively. The phages had strong lytic activity against their host bacteria (E. coliNCTC 12900, ATCC 43888, and ATCC 35150) at 5-37 celcius and adsorbed to their host cells by 92.7-97.5% in the first five minutes of incubation. These phages are thought to be good candidates as therapeutic and biocontrol agents againstE. coliO157:H7 in the veterinary science and food industry due to short latent period, high burst size, rapid development in host cells, high lytic activity, high adsorption rate, stability over a wide pH range and high temperature, and absence ofstx1andstx2genes.Öğe Inhibitory effect of bacteriocins against Escherichia coli O157:H7(Sage Publications Ltd, 2019) Oncul, Nilguen; Yildirim, ZelihaThe purpose of this study was to explore the activity of bacteriocin enterocin KP and lactococcin BZ against Escherichia coli O157:H7, a Gram-negative foodborne pathogen, in ultra-high temperature (UHT) milks with different fat ratios. Enterocin KP and lactococcin BZ were produced from two bacteriocinogenic strains, isolated in previous studies from White cheese and Boza. Full fat (3.0%), half fat (1.5%), and low fat (<0.1% fat) UHT milks inoculated with 10(2), 10(4), and 10(6) CFU/ml of E. coli O157:H7 were treated with different concentrations (400, 800, 1600, and 2500 AU/ml) of lactococcin BZ, enterocin KP, or a combination of both and stored at 4 or 20 celcius for 20 days. The survival of E. coli O157:H7 was determined at both storage temperatures during the storage period of 20 days. Lactococcin BZ and enterocin KP had a bactericidal impact on E. coli O157:H7 in all UHT milk samples either separately or in combination. However, antibacterial activity of the bacteriocins decreased with increasing fat content of milk and inoculum levels of bacterium. The results of this study indicate that lactococcin BZ and enterocin KP may be useful candidates either separately or in combination as biopreservatives for use in the dairy industry to control the growth of pathogenic microorganisms.Öğe Inhibitory effect of enterocin KP in combination with sublethal factors on Escherichia coli O157:H7 or Salmonella Typhimurium in BHI broth and UHT milk(TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY, 2014) Yildirim, Zeliha; Ilk, Yaselin; Yildirim, Metin; Tokatli, Kader; Oncul, NilgunThe effects of physical and chemical sublethal treatments on the antibacterial activity of enterocin KP produced by Enterococcus faecalis KP against Escherichia coli O157:H7 and Salmonella Typhimurium were investigated. Enterocin KP was not active against intact cells of E. coli O157: H7 or S. Typhimurium. However, the use of enterocin KP together with ethylenediaminetetraacetic acid (50 mM), sodium tripolyphosphate (50 mM), sublethal heating (60 degrees C for 10 min), cold shock (-20 degrees C for 2 h), or acid stress (mixture of 40% lactic acid, 16% propionic acid, 16% acetic acid) in BHI medium decreased the cell number of E. coli O157: H7 by 7.27, 6.28, 3.39, 3.06, 4.20 log and S. Typhimurium by 7.21, 6.20, 3.64, 3.38, 3.98 log cfu/mL, respectively. The combination of enterocin KP with ethylenediaminetetraacetic acid decreased the cell number of E. coli O157: H7 in UHT milk to undetectable level, enterocin KP plus sodium tripolyphosphate or enterocin KP plus sublethal heating caused a reduction by 6.07 and 5.68 log cycles. The results of this study showed that enterocin KP could be applied as a biopreservative to inhibit E. coli O157: H7 and S. Typhimurium in combination with physical and food grade chemical hurdles.Öğe Inhibitory Effect of Lactococcin BZ Against Listeria innocua and Indigenous Microbiota of Fresh Beef(FACULTY FOOD TECHNOLOGY BIOTECHNOLOGY, 2016) Yildirim, Zeliha; Yerlikaya, Sabire; Oncul, Nilgun; Sakin, TubaIn this study, the effect of lactococcin BZ on microbiological quality of fresh beef is investigated. For this purpose, the meat samples were treated with various amounts of lactococcin BZ (200-2500 AU/mL), a bacteriocin produced by Lactococcus lactis spp. lactis BZ, and kept at 4-5 degrees C for 12 days. During storage, the microbiological properties of the meat samples with or without lactococcin BZ were determined. Inhibitory effect of lactococcin BZ depended on its amount. The higher the amount of lactococcin BZ, the higher the inhibitory activity. Treatment with lactococcin BZ at the level of 2500 AU/mL resulted in 4.87, 3.50 and 3.94 log cycle decrease in the counts of mesophilic, psychrotrophic and lactic acid bacteria, respectively, and 1.90.10(4) and 1.04.10(2) CFU/g reduction in conform and faecal conform bacteria, respectively, at the end of storage as compared to their initial numbers in the control sample. However, the counts of these bacteria in control samples increased during storage. Also, lactococcin BZ at 1600 AU/mL showed very strong antilisterial effect against Listeria innocua in fresh meat and reduced the cell numbers from 6.04 log CFU/g to undetectable level on the 6th day of storage. In conclusion, lactococcin BZ has a potential use as a biopreservation agent to improve safety and shelf life of raw beef.Öğe Isolation and Characterization of Lytic Bacteriophages Specific to Foodborne Pathogenic Pseudomonas aeruginosa and Use as a Biopreservative in Chicken Meat(Springer, 2024) Yilmaz, Nazife; Yildirim, Zeliha; Sahin, Tuba Sakin; Karaoglan, MertIn this study, bacteriophages specific to Pseudomonas aeruginosa strains were isolated from wastewaters, and their potential to be used as a bioprotective in chicken meat was investigated. Then, among the 35 isolated bacteriophages, two phages (vB_PaeS-K10 and vB_PaeS-K13) with a wide host cell range and strong clear plaque formation were selected and their morphological, physical-chemical, and genetic properties and their inhibitory effects against the host cell in chicken meat were determined. As a consequence of the examination by TEM (transmission electron microscopy), vB_PaeS-K10 and vB_PaeS-K13 phages belong to the family Siphoviridae of the order Caudovirales. The genome size, multiplicity of infection value, latent period, burst time, and burst size of vB_PaeS-K10 phage were 54.20 kb, 10, 75 min, 30 min, and 34.86, respectively, whereas those of vB_PaeS-K13 phage were 44.06 kb, 0.01, 20 min, 35 min, and 35.95. Both of them were resistant to high temperature and entirely active between pH 3 and 12, and the rate of absorption of the phages against their host cells increased with Ca2+ ions. Lytic activity test revealed that both phages reduced host cell density in LB broth at 4 degrees C and 37 degrees C. Moreover, vB_PaeS-K10 and vB_PaeS-K13 phages lethally infect P. aeruginosa at 4 degrees C in chicken meat, and this situation is the evidence of their potential to be utilized as bioprotective in chicken meat.Öğe Microbiological, antimicrobial and antioxidant characteristics of commercial Turkish kefirs(M H Schaper Gmbh Co Kg, 2021) Oncul, Nilgun; Ozbey, Ayse; Erinc, Hakan; Yildirim, ZelihaIn this study, the microbiological properties, physicochemical characteristics, antimicrobial and antioxidant activities of Turkish commercial kefir products were investigated. The enumeration of Lactococci, aerobic lactobacilli, anaerobic lactobacilli, acetic acid bacteria (AAB) and yeast were performed by spread plate technique and counted as 7.35, 6.62, 6.85, 6.24 and 2.35 log CFU/g, respectively. Antimicrobial activity of kefir was evaluated using the disk diffusion method. Ten microorganisms, including seven Grampositive strains and three Gram-negative strains were tested. While Listeria monocytogenes, L. ivanovii and Escherichia coli were the sensitive bacteria for all kefir samples, L. plantarum, Staphylococcus aureus, Bacillus cereus and E. coli O157:H7 are the resistant bacteria. The means of pH, total phenolic content, Trolox Equivalent Antioxidant Capacity (TEAC) and lipid peroxidation were 4.03, 4.39 mg GAE/100mL, 0.15 mu mol Trolox/mL and 7.23%, respectively. From the beneficial health properties point of view, kefir appears to be a promising food.Öğe Microbiological, physicochemical, and sensory characteristics of kefir produced by secondary fermentation(Croatian Dairy Union, 2018) Yildiz-Akgul, Filiz; Yetisemiyen, Atila; Senel, Ebru; Yildirim, ZelihaIn this study, the microbiological, physicochemical, and sensory properties and volatile aromatic compounds of kefir produced by secondary fermentation were investigated. Cow milk samples containing 1.5 % fat were fermented with kefir grains until the pH reached certain levels (pH 5.0-5.5), and then each of them was inoculated with a different starter culture (thermophilic, probiotic, mesophilic aromatic, and yeast) for secondary fermentation. In kefir samples produced traditionally or by secondary fermentation, the pH values, carbon dioxide levels, and tyrosine and lactic acid contents increased during storage. However, the counts of lactococcus, lactobacillus, leuconostoc, and yeasts decreased. Acetaldehyde and ethanol increased during storage, but diacetyl decreased in kefir samples produced traditionally or by secondary fermentation. The butanone contents changed very little but they showed an upward trend within the storage period. Kefir samples produced by secondary fermentation found greater acceptance during sensory testing than samples produced by the traditional method. Kefir inoculated with mesophilic aromatic and yeast cultures were the most preferred by panelists.Öğe The inhibitory effect of lactoccocin BZ against Escherichia coli on fresh beef(M H Schaper Gmbh Co Kg, 2024) Oncul, Nilgun; Tokatli, Kader; Yildirim, ZelihaDuring the processing of fresh meat, there is a risk of contamination with foodborne pathogenic E. coli. The use of bacteriocins is considered to ensure the safety of fresh meat. In this context, the impact of lactococcin BZ on the E. coli population in fresh beef has been investigated. The antibacterial activity of lactococcin BZ was observed in meat samples inoculated with E. coli both during and after attachment condition (10(3) and 10(6) CFU/mL), and over a 12 days storage period in refrigeration (4 degrees C). Different amounts of lactococcin BZ (ranging from 400 to 3200 AU/mL) were applied to fresh meat for varying treatment durations (0-30 minutes). Following the application of lactococcin BZ at levels of 800, 1600, and 3200 AU/mL during attachment, E. coli counts were immediately reduced by 3.62 log units. At high inoculum dose, lactococcin BZ (3200 AU/mL) decreased the pathogen by approximately 6 log units in 5 minutes during attachment. E. coli exhibited sensitivity to lactococcin BZ (400, 1600, and 3200 AU/mL) both in low and high inoculum doses after attachment to fresh beef. Furthermore, the inhibitory effect of lactococcin BZ increased with its concentration over the 12 days of refrigerated. In conclusion, lactococcin BZ demonstrated inhibitory effect against E. coli in fresh beef, suggesting its potential use as a biopreservative in the meat industry.Öğe Ultrasound-assisted extraction of antioxidant phenolic compounds from Lavandula angustifolia flowers using natural deep eutectic solvents: An experimental design approach(Elsevier, 2021) Alasalvar, Hamza; Yildirim, ZelihaIn this study, the green extraction of antioxidant phenolic compounds from Lavandula angustifolia was investigated using ultrasound-assisted extraction coupled with natural deep eutectic solvents (NADESs). One variable at a time, fractional factorial design, steepest ascent/descent method, and central composite design were used to optimize the extraction conditions. Eighteen NADESs based on choline chloride, organic acids, and sugars were tested by one variable at a time approach. The NADES composed of choline chloride and glycerol with a molar ratio of 1:2 showed higher extraction performance than other NADESs and benchmark solvents (70 % ethanol and 80 % methanol). After solvent selection, other extraction parameters including ultrasound amplitude (20-100 %), temperature (40-70 degrees C), time (5-30 min), liquid to solid ratio (10-50 mL/g), and water content in NADES (10-50 %) were screened using fractional factorial design. Subsequently, the steepest ascent/descent method was applied to approach the suitable level of the selected parameters. Finally, response surface methodology was used to determine the optimal extraction conditions. The optimum conditions were ultrasound amplitude of 60 %, temperature of 60 degrees C, time of 17.5 min, liquid to solid ratio of 31.7 mL/g, and water content in NADES of 33.5 % with the predicted phenolic content of 50.50 mg gallic acid equivalent/g, flavonoid content of 35.79 mg catechin equivalent/g, antioxidant capacity (AC)(DPPH )of 41.60 mg Trolox equivalent (TE)/g, AC(ABTS) of 77.13 mg TE/g, and AC(CUPRAC) of 163.33 mg TE/g. Phenolics and volatiles were analyzed by HPLC and GC-MS, respectively. The results showed a sustainable, green, and effective extraction of antioxidant phenolic compounds from L. angustifolia.
