Food Engineering / Gıda Mühendisliği
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Article Citation - WoS: 1Orta Nemli İncirlerde Depolama Sonrasında Pektin Metil Esteraz Aktivitesi Değişimi(Pamukkale Üniversitesi, 2015) Demirbüker Kavak, Dilek; Yemenicioğlu, AhmetOrta nemli meyveler, kurutulmuş meyvelerin rehidre edilmesiyle elde edilebilmektedirler. Kuru meyvelere kıyasla doğrudan tüketime daha uygun olan orta nemli meyveler, sanayide unlu mamüller, süt ürünleri, şekerlemeler kullanılabilmektedirler. Bu çalışmanın amacı orta nemli hale getirilmiş incirlerin 3 aylık depolama süresi sonucunda mikrobiyal stabilitelerinin ve dokuda yumuşamaya neden olan pektin metil esteraz enzimi (PME) aktivitelerinin kıyaslanmasıdır. Bu amaçla kuru incirler 30°C ve 80°C'de suyla %30 nem içeriğine ulaşana kadar rehidre edilmişlerdir. Rehidre edilmiş örnekler, 3 ay süreyle +4°C'de depolanmışlardır. Depolama süresi sonunda toplam canlı sayımı sonuçlarına göre 30°C kontrol örnekleri ile 80°C'de rehidre edilmiş örnekler arasında istatistiksel olarak anlamlı bir fark bulunmamıştır. Depolama süresi sonucunda PME aktivitesi, kontrol örnekleri için 24.1 ?mol COOH dk-1g-1 iken, 80°C'de rehidre edilmiş orta nemli incirlerde 17.4 ?mol COOH dk-1g-1bulunmuştur. Sonuç olarak incirleri orta nemli hale getirmek için 80°C'de gerçekleşen rehidrasyon işlemi, depolama sonrası mikrobiyal yükü belirgin şekilde etkilememesine karşın, yumuşamaya neden olan PME aktivitesini 30°C'de rehidre edilmiş kontrol örneklerine kıyasla %28 oranında azaltmaktadır.Article Siyah Meyveli İncir Çeşitlerinin Kurutularak Değerlendirilmesi(Pamukkale Üniversitesi, 2015) Konak, Ramazan; Kösoğlu, İlknur; Tan, Nilgün; Kocataş, Hilmi; Yemenicioğlu, Ahmetİncir, yüksek oranda diyet lif, fenolik madde ve mineralleri içeren bir meyvedir. Ülkemizin sahip olduğu zengin incir mirası göz önüne alındığında antioksidan kapasitesi çok yüksek, renkli çeşitler mevcut olmasına rağmen bunların kurutularak değerlendirilme uygulamaları yok denecek kadar azdır. Bu çalışma ile İncir Araştırma Enstitüsü genetik kaynaklar parselinde bulunan siyah renkli çeşitlerden 9 tanesi ve standart kurutmalık çeşitler olan Sarılop ve Sarızeybek çeşitleri kullanılmıştır. Meyveler geleneksel yönteme göre kerevetler ile güneş altında kurutulup çeşitlerin kuruma kapasiteleri ve kuru meyve kaliteleri tespit edilmiştir. Standart kurutmalık çeşitlerin yanı sıra 1101, 1102 ve 1012 kod numaralı siyah renkli çeşitlerin kurutmaya uygun olduğu sonucuna varılmıştır.Other Sıcaklık ve Sürenin Havuç ve Yeşil Fasulyelerde Bulunan Pektin Metilesteraz Enzimi Üzerindeki Etkisinin Belirlenmesi(Gıda Teknolojisi Derneği, 2003) Yemenicioğlu, Ahmet; Cemeroğlu, BekirHavuç ve yeşil fasulyelerden elde edilmiş ekstrakte ve homojenatlarda PME enziminin aktivite düzeyi ve termal karakteristikleri belirlenmiştir. Yeşil fasulyelerden elde edilmiş homojenatlarda havuçlara kıyasla 2.6 kat daha fazla PME aktivitesi bulunduğu saptanmıştır. Çözünür, iyonik ve kovalent bağlı PME fraksiyonlarının yüzde dağılımı y. fasulyelerde sırasıyla; 3, 88,9 ve havuçlarda 0,81, 19 düzeyinde olduğu belirlenmiştir. Homojenatlarda bulunan PME enzimlerinin optimum sıcaklıkları y. fasulylerde; 40$^circ$C, buna karşın havuçlarda; 50$^circ$C'dır. Her iki sebzede de iyonik olarak bağlı PME enzimleri, benzer termal karakteristiklere sahip olup 40$^circ$C'de optimum aktivite göstermektedir. Buna karşın kovalent bağlı enzim fraksiyonunun optimum sıcaklığı, havuçlarda 55$^circ$C, y. fasulyelerde 50$^circ$C dır.Article Citation - WoS: 64Citation - Scopus: 77Development of Flexible Antimicrobial Zein Coatings With Essential Oils for the Inhibition of Critical Pathogens on the Surface of Whole Fruits: Test of Coatings on Inoculated Melons(Elsevier, 2019) Boyacı, Derya; Iorio, Gianmarco; Sözbilen, Gözde Seval; Alkan, Derya; Trabattoni, Silvia; Pucillo, Flavia; Yemenicioğlu, AhmetThis study aimed to develop essential oil (EO)-containing antimicrobial coatings for the inhibition of pathogenic bacteria contamination on fruit peels. Incorporation of eugenol (EUG), carvacrol (CAR), and thymol (THY) into films at > 1% (w/w) eliminated the typical brittleness of zein films. However, EUG outperformed CAR and THY in terms of mechanical properties. Films with >= 2% (w/w) CAR and THY and >= 3% EUG showed clear zones against L. innocua and E. coli in agar medium at 37 degrees C. All EO-containing films also inhibited L. innocua and E. coli inoculated at their surfaces by minimum 3.9 and 2.7 decimal (D) within 1 day at 10 degrees C. Moreover, 2% EUG-containing zein coatings caused 2-3 decimal reduction in L. innocua and E. coli counts of inoculated melon surfaces at 10 degrees C. Unlike the bare zein coatings, flexible EUG-containing films on melons did not show cracking or detachment. Zein films loaded with EUG showed a highly hydrophilic surface. The best oxygen barrier performance was observed for the EUG-richest formulation (i.e., EUG at 3%), and this was attributed to a homogenizing effect of the EO that eventually led to a denser and hole-free network. This work suggested that flexible coatings of zein containing EOs could inhibit pathogens embedded in the rough peel surface of melons.Book Part Strategies for Controlling Major Enzymatic Reactions in Fresh and Processed Vegetables(Taylor & Francis, 2016) Yemenicioğlu, Ahmet[No abstract available]Book Part Citation - WoS: 3Citation - Scopus: 5Basic Strategies and Testing Methods To Develop Effective Edible Antimicrobial and Antioxidant Coating(Elsevier, 2018) Yemenicioğlu, AhmetDue to the continuous increase in microbial outbreaks originated form minimally processed and ready-to-use food [1,2], the active food packaging has become one of the top research topics in food science. A properly designed active packaging might increase the microbial safety or delay the spoilage of food (antimicrobial packaging), it might delay oxidative changes in food (antioxidant packaging), or it might help increasing functional properties of food by delivery of nutrients or bioactive substances to food surface in bioavailable form (bioactive packaging)Article Citation - WoS: 12Citation - Scopus: 16Control of Lactic Acid Bacteria in Fermented Beverages Using Lysozyme and Nisin: Test of Traditional Beverage Boza as a Model Food System(Wiley, 2018) Sözbilen, Gözde Seval; Korel, Figen; Yemenicioğlu, AhmetThe objective of this study was to increase quality and limited shelf-life of boza (3–15 days), a traditional Balkan origin fermented beverage using lysozyme (LYS) and/or nisin (NIS). For this purpose, the effectiveness of NIS, LYS and LYS:NIS combinations was first tested in a broth medium at 4 °C for 3 weeks on Lactobacillus plantarum, one of the frequently isolated lactic acid bacteria in boza. Stability of LYS and NIS in boza, their effects on LAB counts, and chemical and sensory properties of boza were then evaluated during cold storage at 4 °C. Results of LAB counts as well as pH, d- and l-lactic acid, and titratable acidity measurements showed that LAB in boza containing NIS (250 μg g−1) or LYS:NIS (500:250 μg g−1) could be controlled without reducing LAB counts below 6 log CFU mL−1 during 2 weeks shelf-life. In contrast, LYS (500 μg g−1) alone could not control LAB in boza to delay its acidic spoilage. Positive effects of NIS and LYS:NIS application on quality of boza were also proved with sensory analysis by panelists and e-nose measurements. This work showed that use of natural GRAS agents in preservation of fermented beverages containing probiotic LAB is possible without affecting their characteristic aroma and flavour.Article Citation - WoS: 14Citation - Scopus: 23Expanding Horizons of Active Packaging: Design of Consumer-Controlled Release Systems Helps Risk Management of Susceptible Individuals(Elsevier Ltd., 2018) Boyacı, Derya; Yemenicioğlu, AhmetThe objective of this study was the development of zein based antilisterial films that contain a consumer-controlled and pH-triggered release mechanism for lysozyme (LYS). For this purpose, composite films were formed by mixing hydrophobic zein with hydrophilic soy protein isolate (SPI) or lentil protein isolate (LPI). Active property of films was formed by maintaining 30 to 50% of total LYS in free form (LYSfree). On the other hand, the pH-triggered release mechanism was formed by exploiting attractive charge-charge interactions between LYS (pI: 11.4) and SPI or LPI (pI values ≈ 4.5), and binding remaining LYS (LYSbound) in film matrix. The pH-triggered release mechanism of composite films worked in buffers that had pHs varying between 4.3 and 7.3. The composite films bound majority of LYS between pH 5.3 and 7.3, but they released LYS at pH ≤ 4.5. The pH-triggered release of LYS was achieved with zein-LPI films activated by acidification in packed cold-stored beef, lamb and smoked salmon. The zein-SPI films performed pH-triggered LYS release in packed food with the exception of packed smoked salmon. The LYSfree and LYSbound released from pH-triggered films showed antimicrobial activity on Listeria innocua. Consumer-controlled release mechanisms enable increasing antimicrobial stress over pathogens during transfer from market to home and cold storage at home. Thus, such films could initiate personalized packaged food to help risk management of susceptible individuals.Book Part Citation - WoS: 12Citation - Scopus: 16Zein and Its Composites and Blends With Natural Active Compounds: Development of Antimicrobial Films for Food Packaging(Elsevier Ltd., 2016) Yemenicioğlu, AhmetIn this chapter the current developments in using biopolymer zein for active edible film-making are discussed with particular emphasis on antimicrobial packaging. Recent studies have showed the possibility of developing effective antimicrobial edible packaging materials through the incorporation of different natural antimicrobial compounds, including antimicrobial enzymes, peptides, and phenolic compounds, into zein films. The zein-based films that contain antimicrobial enzyme lysozyme and bacteriocin nisin have great potential as antilisterial edible packaging materials. Additionally, zein-based films that contain natural phenolic compounds might be suitable for antimicrobial, antioxidant, and/or bioactive packaging. The use of composites of zein with waxes and blends of zein with fatty acids enables researchers to obtain antimicrobial zein-based films with controlled release properties.Conference Object Citation - Scopus: 11Effects of Different Drying Methods on Phenolic Content, Antioxidant Capacity and General Characteristics of Selected Dark Colored Turkish Fig Cultivars(International Society for Horticultural Science, 2017) Konak, R.; Köseoğlu, İ.; Yemenicioğlu, Ahmetig fruit is a good source of minerals and crude fibers. The dark-colored fig cultivars rich in anthocyanins are also known with their high polyphenol content. However, although there are many different dark-colored fig cultivars grown in Turkey, the dried fig industry has traditionally been concentrated on drying of several yellow-colored fig cultivars. The aim of this study is to determine the effects of sundrying and oven-drying on some general characteristics, phenolic content and antioxidant capacity of 2 dark-colored (black) and 2 light-colored (yellow) fig cultivars selected from genetic collection of Turkish Fig Research Institute. The figs were obtained by harvesting at the semi-dry stage at 40-50% moisture content and applying sun-drying or oven-drying to reach final moisture content between 20 and 26%. The sun-drying was conducted on mats for 2-3 days under the sun while the oven-drying was applied for 12 h at 60°C and at the air velocity of 0,5 m s-1. The result of the study clearly showed almost 1,5-2 fold higher total phenolic content and ABTS free radical scavenging based antioxidant capacity of fresh dark-colored figs than fresh light-colored ones. The drying had almost no negative effects on the total phenolic content of both dark- and light-colored figs. The drying also did not have a negative effect on antioxidant capacity of light-colored figs, but it caused a limited reduction (between 20 and 30%) in antioxidant capacity of dark-colored figs due to the well-known heat labile nature of their color compounds anthocyanins. The use of sun-drying or oven-drying did not have a considerably different effect on final phenolic contents and antioxidant capacities of dried figs. This study clearly showed that it is possible to obtain phenolic rich dried figs by use of dark colored fig cultivars such as TR1101 and TR1102.