Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 16Citation - Scopus: 18Microencapsulation of a Potential Probiotic Lactiplantibacillus Pentosus and Its Impregnation Onto Table Olives(Elsevier, 2022) Elvan, Menşure; Baysal, Ayşe Handan; Harsa, Hayriye ŞebnemThis study aimed to demonstrate some probiotic properties of Lactiplantibacillus pentosus NRRL B-227 and impregnate the strain onto the table olive surfaces. In this respect, antioxidative ability, antibiotic resistance, and survivability after simulated digestion tests were carried out. Microencapsulation was performed using xylan and whey protein concentrate (WPC) using the water-in-oil emulsion technique to maintain cell viability. A vacuum impregnation process was performed to coat olive surfaces with L. pentosus. This strain demonstrated 71.6% DPPH radical scavenging activity and exhibited paramount resistance to antibiotics. The viable cell count of microencapsulated L. pentosus was found as 8 log CFU/g after 72 weeks of storage. After exposure to the simulated oral phase, 1-log reduction was detected, and gastric phase conditions led to a 3-log reduction of viability of microencapsulated as well as non-microencapsulated cells. The viability of microencapsulated L. pentosus on the surface of olives was also evaluated for one-month, and viable cell count was ≥6 log CFU/g. In the light of these findings, L. pentosus with antibiotic and digestion fluids resistant and antioxidant properties were successfully microencapsulated within xylan-WPC complex. Table olives can be considered as a suitable carrier for beneficial microorganisms that satisfies with the expectations of regulations for functional foods.Article Uv-c Uygulamasının Sıvı Yumurta Beyazının Mikrobiyolojik Kalitesi Üzerine Etkisi(Gıda Teknolojisi Derneği, 2010) Ünlütürk, Sevcan; Baysal, Ayşe Handan; Atılgan, Mehmet R.Sıvı yumurta beyazı, kabuğundan ayrılmış yarı geçirgen (opak) görünümlü yumurta ürünüdür. Sıvı yumurta beyazı, düşük sıcaklık ve kısa sürelerde pastörize edilerek dayanıklı hale getirilmektedir. Ancak yüksek protein içeriği nedeni ile ısıl işlem ürün kalitesini olumsuz yönde etkilemektedir. Bu çalışma, ısıl işleme alternatif olarak öne sürülen UV-C ışınlama yöntemiyle sıvı yumurta beyazının mikrobiyolojik kalitesinin incelenmesini kapsamaktadır. Bu amaçla; yumurta beyazı örnekleri, E. coli 0157-.H7 (ATCC 700728), L. innocua (NRRL-B 33314) ve E. coli K-12 (ATCC 25253) ile inoküle edilerek belli dozlarda UV-C ışın uygulamasına tabi tutulmuştur. Denemeler 0-100 mJ/cm2UV doz aralığı ve 1.315 mW/cm2 UV şiddetinde, laboratuvar ölçekli UV dezenfeksiyon cihazı kullanılarak gerçekleştirilmiştir. Elde edilen sonuçlara göre, E. coli 0157:H7, E. coli K-12 ve L. innocua sayılarında maksimum 3.206±0.777 log, 2.719±0.63 log ve 2.624±0.268 log kob/mL azalma saptanmıştır. Sıvı yumurta beyazı üretiminde, UV-C ışınlarının bir ön işlem olarak kullanılabileceği ve ürünün mikrobiyolojik stâbilitesini artırılabileceği sonucuna varılmıştır.Article Citation - WoS: 5Modeling Growth of Alicyclobacillus Acidoterrestris Dsm 3922 Type Strain Vegetative Cells in the Apple Juice With Nisin and Lysozyme(AIMS Press, 2017) Molva, Çelenk; Baysal, Ayşe HandanIn the present study, the effect of storage temperature on A. acidoterrestris DSM 3922 cells (105 CFU/mL) was examined during growth in reconstituted apple juice (pH 3.8, degrees Brix 11.3) containing nisin (0-100 IU/mL) and lysozyme (0-100 mg/L). The growth curves were obtained at three temperatures of 27, 35 and 43 degrees C using absorbance data (OD600nm). Based on the results, the minimal inhibitory concentrations (MICs) of nisin were found as 10 IU/mL at all tested temperatures. On the other hand, increasing the temperature decreased the amount of lysozyme for growth inhibition. The MICs of lysozyme were found as 10, 2.5 and 1.25 mg/L at 27, 35 and 43 degrees C, respectively. At selected non-inhibitory doses, nisin (1.25-5 IU/mL) and lysozyme (0.3-2.5 mg/L) prolonged the lag time compared to the controls at the corresponding temperatures. In addition, there was a strong linear relationship between the lag time and lysozyme concentrations at 27 and 35 degrees C (R-2 > 0.98). The results of this study demonstrated that both nisin and lysozyme could be used to inhibit the growth of A. acidoterrestris cells in the apple juice. The results also indicated that the growth parameters were variable depending on the storage temperature and the type of the antimicrobial agent used in the apple juice.Article Citation - WoS: 13Citation - Scopus: 17Characterization of Antimicrobial Activities of Olive Phenolics on Yeasts Using Conventional Methods and Mid-Infrared Spectroscopy(Springer, 2019) Canal, Canan; Özen, Banu; Baysal, Ayşe HandanOlive fruit is very rich in terms of phenolic compounds. Antimicrobial activities of various phenolic compounds against bacteria and fungi are well established; however, their effects on yeasts have not been examined. Aim of this study was to investigate the antimicrobial effects induced by olive phenolic compounds, including tyrosol, hydroxytyrosol, oleuropein, luteolin and apigenin against two yeast species, Aureobasidium pullulans and Saccharomyces cerevisiae. For this purpose, yeasts were treated with various concentrations (12.5-1000ppm) of phenolic compounds and reduction in yeast population was followed with optical density measurements with microplate reader, yeast colony forming units and mid-infrared spectroscopy. All phenolic compounds were effective on both yeasts, especially 200ppm and higher concentrations have significant antimicrobial activity; however, effects of lower levels depend on the type of phenolic compound. According to mid-infrared spectral data, significant changes were observed in 1200-900cm(-1) range corresponding to carbohydrates of yeast structure as a result of exposure to all phenolic compounds except tyrosol. Spectra of tyrosol and luteolin treated yeasts also showed changes in 1750-1500cm(-1) related to amide section and 3600-3000cm(-1) fatty acid region. Since phenolic compounds from olives were effective against yeasts, they could be used in food applications where yeast growth showed problem. In addition, FTIR spectroscopy could be successfully used to monitor and characterize antimicrobial activity of phenolic compounds on yeasts as complementary to conventional microbiological methods.Book Part Citation - Scopus: 21Short-Wave Ultraviolet Light Inactivation of Pathogens in Fruit Juices(Elsevier, 2018) Baysal, Ayşe HandanFruit juice processing techniques are continuously developing to conform to modern consumer demands for safe, nutritious, tasty, natural, and fresh-like products. Short-wave ultraviolet (UV-C) light has been proven to be a suitable alternative processing method because of its positive consumer image and low processing cost. The use of UV-C light at 253.7. nm for food processing is safe and has been approved as an alternative treatment to reduce pathogens and other microorganisms in the production, processing, and handling of foods. The bactericidal mechanism of UV-C is based on the absorption of UV-C light by microbial DNA or RNA structures and the formation of pyrimidine dimers, preventing replication, making pathogens inactive and unable to cause infection. Fruit juices have a range of optical and physical properties and diverse chemical compositions that influence UV-C efficacy. Thus, this chapter describes the effect of UV-C light applications on the inactivation of pathogens in fruit juice and critical factors to ensure efficient treatment. © 2018 Elsevier Inc. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Comparison of Conventional Culture Method and Fluorescent in Situ Hybridization Technique for Detection of Listeria Spp. in Ground Beef, Turkey, and Chicken Breast Fillets in Izmir, Turkey(International Association for Food Protection, 2014) Baysal, Ayşe HandanThe occurrence of Listeria species in refrigerated fresh chicken breast fillet, turkey breast fillet, and ground beef was evaluated, comparing the conventional culture method and fluorescent in situ hybridization (FISH). FISH uses hybridization of a nucleic acid sequence target of a microorganism with a specific DNA probe labeled with a fluorochrome and imaging by a fluorescence microscope. First, Listeria was inoculated in chicken breast fillet, turkey breast fillet, or ground beef, and the applicability of the FISH method was evaluated. Second, Listeria was detected in fresh chicken breast fillet, turkey breast fillet, and ground beef by culture and FISH methods. Listeria was isolated from 27 (37.4%) of 216 samples by the standard culture method, whereas FISH detected 25 (24.7%) preenriched samples. Of these isolates, 17 (63%) were L. innocua, 6 (22%) L. welshimeri, and 4 (14.8%) L. seeligeri. Overall, the prevalences of Listeria spp. found with the conventional culture method in chicken breast fillet, turkey breast fillet, and ground beef were 9.7, 6.9, and 20.8%, whereas with the FISH technique these values were 11.1, 6.9, and 16.7%, respectively. The molecular FISH technique appears to be a cheap, sensitive, and time-efficient procedure that could be used for routine detection of Listeria spp. in meat. This study showed that retail raw meats are potentially contaminated with Listeria spp. and are, thus, vehicles for transmitting diseases caused by foodborne pathogens, underlining the need for increased precautions, such as implementation of hazard analysis and critical control points and consumer food safety education.Article Citation - WoS: 5Citation - Scopus: 6The Effect of Sporulation Medium on Alicyclobacillus Acidoterrestris Guaiacol Production in Apple Juice(Academic Press Inc., 2016) Molva, Çelenk; Baysal, Ayşe HandanThe present study evaluated the effect of sporulation medium on guaiacol formation from vanillin and vanillic acid by Alicyclobacillus acidoterrestris DSM 3922 in the reconstituted apple juice (pH 3.82, °Brix 11.3). For sporulation, potato dextrose agar and Bacillus acidoterrestris agar were used. After heat-activation, spores were turned into vegetative cells and inoculated into juice samples to a final concentration of 103 or 105 CFU/mL. Samples were incubated at 37 °C for 264 h and guaiacol concentration was determined using peroxidase enzyme colourimetric assay. Based on the results, the conversion of vanillic acid into guaiacol was faster than that of vanillin among both cell suspensions. Also, there were no significant differences among any of the samples inoculated into apple juice spiked with vanillin at the end of the incubation period (P > 0.05). In the case of vanillic acid, the guaiacol concentrations were significantly different among cells activated from spores produced on PDA and BATA (P < 0.05). The obtained results suggested that type of sporulation medium composition may affect the guaiacol concentration depending on inoculum level and type of precursor present in the apple juice.Article Citation - WoS: 2Citation - Scopus: 2Microbial Profile and Bacterial Characterisation of Naturally Debittered Hurma Olives Compared To Non-Debittered Erkence Variety During Ripening Period(John Wiley and Sons Inc., 2016) Sözbilen, Gözde Seval; Baysal, Ayşe HandanNaturally debittered Hurma olive is grown in a specific area in Karaburun peninsula in Turkey. It is characterised by its sweet taste and it differs from other varieties by losing its bitterness caused by phenolic compounds during its maturation period on the tree. Therefore, Hurma olive does not require any further debittering process to be served as table olive. This study was particularly interested in the comparison of the microbial profile of Hurma olive during its 8 weeks of maturation period in two subsequent harvest years and Erkence (not naturally debittered) olive. In addition, main bacterial profile of both Hurma and Erkence olives were isolated and identified. Aerobic mesophilic microorganism (AMM), lactic acid bacteria (LAB), Enterobacteriaceae, Pseudomonadaceae, Staphylococci, Micrococcaceae, yeasts and moulds (Y&Ms) were detected (counted and isolated) in the olive drupes during the maturation period. Isolated bacteria were identified as different spp. of Bacillaceae, Enterobacteriaceae, Micrococcoceae and Pseudomonadaceae.Article Citation - WoS: 9Citation - Scopus: 12Effects of Pomegranate and Pomegranate-Apple Blend Juices on the Growth Characteristics of Alicyclobacillus Acidoterrestris Dsm 3922 Type Strain Vegetative Cells and Spores(Elsevier Ltd., 2015) Molva, Çelenk; Baysal, Ayşe HandanThe present study examined the growth characteristics of Alicyclobacillus acidoterrestris DSM 3922 vegetative cells and spores after inoculation into apple, pomegranate and pomegranate-apple blend juices (10, 20, 40 and 80%, v/v). Also, the effect of sporulation medium was tested using mineral [Bacillus acidoterrestris agar (BATA) and Bacillus acidocaldarius agar (BAA)] and non-mineral containing media [potato dextrose agar (PDA) and malt extract agar (MEA)]. The juice samples were inoculated separately with approximately 105CFU/mL cells or spores from different sporulation media and then incubated at 37°C for 336h. The number of cells decreased significantly with increasing pomegranate juice concentration in the blend juices and storage time (p<0.001). Based on the results, 3.17, 3.53, and 3.72 log cell reductions were observed in 40%, 80% blend and pomegranate juices, respectively while the cell counts attained approximately 7.17logCFU/mL in apple juice after 336h. On the other hand, the cell growth was inhibited for a certain time, and then the numbers started to increase after 72 and 144h in 10% and 20% blend juices, respectively. After 336h, total population among spores produced on PDA, BATA, BAA and MEA indicated 1.49, 1.65, 1.67, and 1.28 log reductions in pomegranate juice; and 1.51, 1.38, 1.40 and 1.16 log reductions in 80% blend juice, respectively. The inhibitory effects of 10%, 20% and 40% blend juices varied depending on the sporulation media used. The results obtained in this study suggested that pomegranate and pomegranate-apple blend juices could inhibit the growth of A. acidoterrestris DSM 3922 vegetative cells and spores.Article Citation - WoS: 62Citation - Scopus: 73Antioxidant and Antimicrobial Activities of Thyme and Clove Essential Oils and Application in Minced Beef(John Wiley and Sons Inc., 2015) Zengin, Hatice; Baysal, Ayşe HandanIn this study, thyme and clove essential oils (EOs) were studied for their chemical composition, antioxidant, antiradical and antibacterial activity and application in ground beef. Carvacrol (75.27%) and eugenol (75.2%) were detected by gas chromatography-mass spectrometry analysis as the main components of thyme and clove EOs, respectively. Broth microdilution method showed all bacteria inhibited by the EOs, while Shewanella putrefaciens and Listeria innocua were the most resistant bacteria to thyme and clove EOs, respectively. EO treatment restricted the growth of artificially inoculated Salmonella typhimurium and native Coliforms in the ground beef. Antioxidant activity determined by ferric-reducing antioxidant power and 1,1 diphenyl-2-picrylhydrazyl methods demonstrated that clove EO had higher in vitro antioxidant activity than thyme EO. Similar results were obtained in ground beef application using 2-thiobarbituric acid value. EOs of clove (2MIC) exerted remarkable higher antioxidant activity in ground beef than EOs of thyme (4MIC), which represent valid alternative antioxidant in meat products. Practical Applications: Plant essential oils (EOs) serve as a "safe" alternative to chemical or synthetic antimicrobials and antioxidants to struggle with the foodborne pathogens or spoilage organisms, inhibiting lipid oxidation and thus extending shelf life. Antioxidant activity determined by ferric-reducing antioxidant power and 1,1 diphenyl-2-picrylhydrazyl methods showed that clove EO had higher in vitro antioxidant activity than thyme EO. Results obtained using 2-thiobarbituric acid value in ground beef application were found similar. EOs of clove (2MIC) exerted higher antioxidant activity in ground beef than EOs of thyme (4MIC). Therefore, EOs could be a valid alternative antioxidant in meat products.