Food Engineering / Gıda Mühendisliği

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  • Article
    Effect of Partial Replacement of Sucrose With Stevia and Sucralose on the Physicochemical and Structural-Mechanical Properties of Apple Marmalade
    (2024) Berk, Berkay; Şirin, Pınar; Ünlütürk, Sevcan
    In this study, low-sugar apple marmalade formulations were developed by partial replacement of sucrose with stevia and sucralose. Their rheological, textural, physicochemical properties and microstructures were evaluated. The concentration of sweeteners was found to have a significant effect on the physicochemical and rheological properties of the formulations. The hardness of marmalades decreased with addition of sweeteners. Herschel–Bulkley model was found to be the best model describing rheological behavior. The consistency index decreased with increasing sweeteners substitution, whereas the flow behavior index showed an increasing trend with the increase of the sweeteners content. Additionally, the microstructure of marmalades with sweetener substitution exhibited a porous structure in the gel network. The increase in sucralose concentration resulted in more surface deformation resulting in weaker gel formation than stevia. Marmalade prepared with 50% stevia substitution was found the best combination and resulted in good sensory properties like marmalade samples containing 500 g sugar.
  • Article
    Identification of Staphylococcus Aureus Cheese Isolates With Respect To Virulence Properties, Genetic Relatedness and Antibiotic Resistance Profiles
    (Özkan Özden, 2019) Kadiroğlu, Pınar; Korel, Figen; Ceylan, Çağatay
    The problems on identification of Staphylococcus aureus isolates from cheese samples wereinvestigated by phenotypic and genotypic tests in this study. Among 207 Staphylococcus spp.isolated from 31 cheese samples, 23 isolates that were Gram positive, catalase and slide coagulasepositive, with 1 isolate that was latex agglutination test negative showed different phenotypicproperties. Polymerase chain reaction (PCR) and quantitative PCR (qPCR) analyses showed thatDNase test and target genes (nuc, coa) regarded as gold standard regions for S. aureus were notfound to be unique for identification of S. aureus. The toxin genes (SEA-SEE) were not detected byPCR. Antibiotic resistance profiles of S. aureus isolates demonstrated that two isolates were resistantto penicillin G. This study showed that the unique phenotypic and genotypic test was not adequatefor identification of S. aureus isolates. There was no correlation between the presence of the nucgene and toxin genes. The presence of nuc gene which was used for detection of S. aureus was alsofound to be present in other Staphylococcus isolates. As a conclusion, the results revealed thatbiochemical tests could lead to false positive results for identification of S. aureus. The presence ofnuc gene is not correlated with the presence of toxin genes.
  • Data Paper
    Knockdown of Death Receptor 5 Antisense Long Noncoding Rna and Cisplatin Treatment Modulate Similar Macromolecular and Metabolic Changes in Hela Cells
    (TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2022) Gürer, Dilek Cansu; Erdoğan Vatansever, İpek; Ceylan, Çağatay; Akgül, Bünyamin
    Background/aim: Despite great progress in complex gene regulatory mechanisms in the dynamic tumor microenvironment, the potential contribution of long noncoding RNAs (lncRNAs) to cancer cell metabolism is poorly understood. Death receptor 5 antisense (DR5-AS) is a cisplatin inducible lncRNA whose knockdown modulates cell morphology. However, its effect on cell metabolism is unknown. The aim of this study is to examine metabolic changes modulated by cisplatin and DR5-AS lncRNA in HeLa cells. Materials and methods: We used cisplatin as a universal cancer therapeutic drug to modulate metabolic changes in HeLa cervix cancer cells. We then examined the extent of metabolic changes by Fourier transform infrared spectroscopy (FTIR). We also performed transcriptomics analyses by generating new RNA-seq data with total RNAs isolated from cisplatin-treated HeLa cells. Then, we compared cisplatin-mediated transcriptomics and macromolecular changes with those mediated by DR5-AS knockdown. Results: Cisplatin treatment caused changes in the unsaturated fatty acid and lipid-to-protein ratios and the glycogen content. These observations in altered cellular metabolism were supported by transcriptomics analyses. FTIR spectroscopy analyses have revealed that DR5-AS knockdown causes a 20.9% elevation in the lipid/protein ratio and a 76.6% decrease in lipid peroxidation. Furthermore, we detected a 3.42% increase in the chain length of the aliphatic lipids, a higher content of RNA, and a lower amount of glycogen indicating relatively lower metabolic activity in the DR5-AS knockdown HeLa cells. Interestingly, we observed a similar gene expression pattern under cisplatin treatment and DR5-AS knockdown HeLa cells. Conclusion: These results suggest that DR5-AS lncRNA appears to account for a fraction of cisplatin-mediated macromolecular ametabolic changes in HeLa cervix cancer cells.
  • Article
    The Use of Organic Sun-Dried Fruits for Delivery of Phenolic Compounds
    (İzzet KARA, 2022) Dervişoğlu, Gökhan; Yemenicioğlu, Ahmet
    The aim of this study is to characterize and increase the total soluble (water soluble + alcohol soluble) phenolic (SPCT) and flavonoid content (SFCT) and total soluble free radical scavenging based antioxidant capacity (SACT) of major sun-dried fruits such as raisins, figs, prunes and apricots. Due to their high insoluble dietary fiber content, the bound antioxidant capacity formed 61 to 67% of the overall antioxidant capacity (water soluble + alcohol soluble + bound) of sun-dried fruits. The SPCT, SFCT and SACT of sun-dried fruits changed between 1675 and 3860 μg catechin/g (d.w.), 161 and 495 μg catechin/g (d.w.) and 13 and 28.5 μmol Trolox/kg (d.w.), respectively. The incorporation of green tea polyphenols into sun-dried raisins, figs and apricots by controlled rehydration conducted in green tea extracts increased their SPCT, SFCT and SACT 1.5 to 1.8 fold, 1.3 to 1.6 fold, and 1.5 to 2.6 fold, respectively. The method applied caused limited increases in SPCT (1.1 fold) and SFCT (1.2 fold) of prunes, but it increased SACT of these fruits 1.6 fold. This study showed the possibility of using sun-dried fruits not only as source of dietary fiber, but also for delivery of phenolic compounds. The methods used in this study for delivery of green tea phenolic compounds to selected organic sun-dried fruits could be an alternative method to increase intake of these invaluable antioxidant compounds and increase functionality of sun-dried fruits which are already accepted as good source of dietary fiber.
  • Article
    Effect of Substrate Concentration and Scale Up on the Polygalacturonase Production
    (Gıda Teknolojisi Derneği, 2019) Göğüş, Nihan; Tarı, Canan
    Pectinases have been used for many industrial applications since long time ago. The largest industrial application of these enzymes is in fruit juice and wine production for the extraction, filtration and clarification and for the maceration of fruits and vegetables. They work by enzymatic breaking down of the cell wall.In this study it was aimed to use the previously optimized shake flask media formulation in batch mode 1 L scale serial bioreactor system and 5 L scale in order to investigate the effects of substrate concentration and scale on PG activity and biomass production. In conclusion it was observed that average PG activity (101.29 U/ml) obtained in 5L scale bioreactor experiments was higher than the maximum PG activity (88.55 U/ml) at 40 g/L orange peel (OP) concentration obtained in the 1 L scale substrate concentration experiment. Furthermore,PG activity increased with an increase in substrate concentration except for 60 g/L orange peel concentration.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    In Vitro Assessment of Food-Derived Bioaccessibility and Bioavailability in Bicameral Cell Culture System
    (Türk Biyokimya Derneği, 2020) Özel Taşcı, Cansu; Pilatin, Gözde; Edeer, Özgür; Güleç, Şükrü
    Background: Functional foods can help prevent metabolic diseases, and it is essential to evaluate functional characteristics of foods through in vitro and in vivo experimental approaches. Objective: We aimed to use the bicameral cell culture system combined with the in vitro digestion to evaluate glucose bioavailability. Materials and methods: Cake, almond paste, and pudding were modified by adding fiber and replacing sugar with sweeteners and polyols. Digestion process was modeled in test tubes. Rat enterocyte cells (IEC-6) were grown in a bicameral cell culture system to mimic the physiological characteristics of the human intestine. The glucose bioaccessibility and cellular glucose efflux were measured by glucose oxidase assay. Results and discussion: The glucose bioaccessibilities of modified foods were significantly lower (cake: 2.6 fold, almond paste: 9.2 fold, pudding 2.8 fold) than the controls. Cellular glucose effluxes also decreased in the modified cake, almond paste, and pudding by 2.2, 4, and 2 fold respectively compared to their controls. Conclusion: Our results suggest that combining in vitro enzymatic digestion with cell culture studies can be a practical way to test in vitro glucose bioaccessibility and bioavailability in functional food development.
  • Article
    Utilization of White Grape Pomace for Lactic Acid Production
    (Gıda Teknolojisi Derneği, 2018) Bayrak, Emrah; Büyükkileci, Ali Oğuz
    Beyaz üzüm posası (BÜP), biyo-temelli kimyasalların fermantasyonla üretimi için kullanılma potansiyeline sahip yüksek miktarda çözünmüş karbonhidrat (glikoz ve fruktoz) içerir. Bu çalışmada, bu atık Lactobacillus casei ile laktik asit (LA) üretilerek değerlendirilmiştir. BÜP kültür ortamına %10 oranında doğrudan eklendiğinde 33.3 g/L LA elde edilmiştir. BÜP'ün sulu özütü daha hızlı bir LA üretimi sağlamıştır. Özüt çıkarma aşamasında posa miktarının artırılması sayesinde daha fazla LA elde edilmiştir ancak, bu işlem üretim verimini kayda değer biçimde düşürmüştür. Tüm koşullarda fruktoz glikoza göre daha yavaş kullanılmıştır. LA üretimi için 10 g/L maya özütü tozu gerekmiştir. Buna alternatif olarak, ekmek mayası otolize uğratılmış ve bu lizat azot kaynağı olarak başarıyla kullanılmıştır. Bulgulara göre, BÜP'ün L. casei ile LA üretimi için sürdürülebilir bir kaynak olduğu düşünülebilir, ancak, posada bulunan diğer maddelerin olası olumsuz etkileri önlenmelidir
  • Article
    The Relationship of Pellet Morphology To Polygalacturonase Production of Rhizopus Oryzae in Various Media Compositions
    (Gıda Teknolojisi Derneği, 2011) Tarı, Canan; Özkan, Kamer; Oncu, Şelale; Avcı, Tuba
    Bu çalışmada, ortam kompozisyonunu belirleyen değişik faktörlerin Rhizopus oryzae pellet morfolojisine ve poligalakturonaz (PG) enzimi üretimine olan etkisi incelenmiştir. En yüksek PG aktivitesine (11.53 U/ml) 4 mg/kg Zn+2 içeren, Mg+2 içermeyen ve pH 3 olan basal ortamında ulaşılmıştır. Karbon kaynağı olarak 14.78 g/l glukoz, 10 g/l galaktoz, 5 g/l mannoz, 0.5 g/l arabinoz ve 19.73 g/l ksilozun birlikte kullanılmıyla da en yüksek PG aktivitesine (27.94 U/ml) ulaşılmıştır. Mısır unu nitrojen kaynağı olarak PG sentezini tetiklemede oldukça etkili olup bir diğer yüksek tetikleyici olan mısır maserasyon sıvısı (CSL) ve $(NH _4)2SO _4$’den %33 daha fazla aktivite vermiştir. $(NH _4)2SO _4$ and 25 g/l glukoz içereren formulasyon ortalama çapı 1.25± 0.25 olan en fazla sayıda pellet oluşumunu sağlamıştır. Ortalama çapı 1.75±0.25 mm olan pelletlerin oluşumu ise yüksek glukoz konsantrasyonuna sahip (50g/l) maya ekstraktı içeren formulasyon ile elde edilmiştir. Uygun karbon kaynağının (glukoz) uygun nitrojen kaynağı (mısır unu) ile interaktif etkisi PG aktivitesini basal ortama göre 4 kat daha arttırmış, ortalama çapı 1.44±0.35mm olan pelletler oluşturmuştur.
  • Article
    Physicochemical and Sensorial Properties of Sepet Cheeses Packaged Under Different Modified Atmospheric Conditions
    (Ege Üniversitesi, 2017) Akpınar, Aslı; Yerlikaya, Oktay; Kınık, Özer; Uysal, Harun Raşit; Korel, Figen
    Çalışmanın amacı farklı modifiye atmosfer koşullarında paketlenen geleneksel Sepet peynirlerinin fiziksel, kimyasal ve duyusal özelliklerini incelemektir. +4 °C' de depolanan Sepet peynirlerinin tüm özellikleri depolamanın 1., 45., 90. ve 180. günlerinde incelenmiştir. Peynirlerin paketlenmesinde 3 farklı modifiye atmosfer koşulu denenmiştir. Üretilen peynirler % 100 N2 (N), % 80 N2 + % 20 CO2 (NC), % 100 CO2 (C) içeren atmosfer koşullarda polistiren ambalajlarda paketlenmiştir. İstatistiksel analiz sonucunda modifiye atmosfer koşullarında (MAP) paketlenen Sepet peyniri örneklerinin kurumadde, kurumadde de yağ % ve kurumadde de tuz % içeriklerinde meydana gelen değişimlerin önemli olduğu tespit edilmiştir. Kitle, tekstür, görünüş, lezzet ve aromayı içeren duyusal özellikler istatistiksel olarak incelendiğinde, sadece CO2 içeren atmosferik koşullarda paketlenen peynirlerde depolama süresince farklılık olduğu gözlenmiştir. Genel olarak bakıldığında % 100 N2 (N), % 80 N2 + % 20 CO2 (NC) gazlarını içeren farklı modifiye koşullarda paketlenmiş olan Sepet peynirlerinin fizikokimyasal ve duyusal özelliklerini daha iyi muhafaza ettiği görülmüştür
  • 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.