Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Nanoteknolojinin Gıda Bilim ve Teknolojisi Alanındaki Uygulamaları(Gıda Teknolojisi Derneği, 2010) Tarhan, Özgür; Gökmen, Vural; Harsa, Hayriye ŞebnemNanobilim ve nanoteknoloji çağımızın en önemli araştırma ve uygulama alanlarından biri olarak hızla gelişmektedir. Başlıca, elektronik, bilgisayar, malzeme, tekstil ve ilaç sanayinde kullanımına yönelik çalışmaların yürütüldüğü bu teknolojinin, gıda ve ziraat alanlarında da çok çeşitli uygulamaları öngörülmektedir. Gıda işleme, yeni fonksiyonel ürünlerin geliştirilmesi, biyoaktif maddelerin taşınması ve kontrollü salınımı, patojenlerin tesbiti, yeni paketleme ürünlerinin geliştirilerek raf ömrünün uzatılması gibi uygulamalar nanoteknolojinin potansiyel gıda uygulamaları arasında yer almaktadır. Protein, karbonhidrat ve yağ kaynaklı nanoparçacıklarla, gıda ürünlerine içerik, tekstür, aroma anlamında istenilen özelliklerin kazandırılması sağlanabilecektir. Bu makalede; nanoteknolojinin gıda alanına uygulamaları üzerine yapılan araştırmalar ve öngörüler derlenmiştir. Bunun yanısıra gıda kaynaklı nanoparçacıklar, üretim ve karakterizasyon yöntemleri ve nanoteknoloji ürünü gıdaların güvenliğine ilişkin bilgilerde sunulan derlemede yer almaktadırlar.Article Citation - WoS: 78Citation - Scopus: 83Rheological and Structural Characterization of Whey Protein Gelation Induced by Enzymatic Hydrolysis(Elsevier, 2016) Tarhan, Özgür; Spotti, Maria Julia; Schaffter, Sam; Corvalan, Carlos M.; Campanella, Osvaldo H.Whey proteins hydrolyzed by Bacillus licheniformis protease (BLP) form soft and turbid aggregate gels with potential food and biotechnological applications. The purpose of the study was to characterize protease-induced whey protein gelation by comparing different protein and enzyme concentrations in terms of gel mechanical and microstructural properties, and conformational changes in the protein secondary structure due to hydrolysis and gelation. Gels formed with whey protein isolate (WPI), at concentrations 5 and 10% (w/v), and BLP concentrations, BLP/WPI (w/w), of 1, 3, and 5% were studied. Regardless of the enzyme concentration, gels with 10% WPI were strong and elastic while those with 5% WPI were weak. Gelation time decreased as the enzyme concentration increased for both protein concentrations. Gel strengths values of 10% WPI samples were independent of BLP concentrations at the end of the incubation period. Creep tests performed on the resulting gels showed that 10% WPI gels with different BLP concentration had similar elasticity, slightly increasing with BLP amount. Remarkable differences were observed in the microstructures of gel prepared with different concentrations of protein and BLP. Changes in the protein secondary structure measured during the gelation were small before gelation. However, sudden changes were observed when the samples gelled, and also after 7 h of incubation at 50 degrees C (time in which samples reached a plateau in G* as seen by rheology tests). Results revealed that without enzyme, hydrolysis of the protein was not promoted and the protein secondary structure remains the same; only a slight denaturation was observed when the protein was incubated at 50 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.Article Citation - WoS: 24Citation - Scopus: 25Investigation of the Structure of Alpha-Lactalbumin Protein Nanotubes Using Optical Spectroscopy(Cambridge University Press, 2014) Tarhan, Özgür; Tarhan, Enver; Harsa, ŞebnemAlpha-lactalbumin (α-la) is one of the major proteins in whey. When partially hydrolysed with Bacillus licheniformis protease, it produces nanotubular structures in the presence of calcium ions by a self-assembly process. This study presents investigation of α-la protein structure during hydrolysis and nanotube formation using optical spectroscopy. Before spectroscopic measurements, nanotubes were examined with microscopy. The observed α-la nanotubes (α-LaNTs) were in the form of regular hollo strands with a diameter of about 20 nm and the average length of 1 μm. Amide and backbone vibration bands of the Raman spectra displayed remarkable conformational changes in α and β domains in the protein structure during nanotube growth. This was confirmed by the Fourier-transform infrared (FTIR) spectroscopy data. Also, FTIR analysis revealed certain bands at calcium (Ca++) binding sites of COO- groups in hydrolysed protein. These sites might be critical in nanotube elongation.Article Citation - WoS: 13Citation - Scopus: 14Nanotubular Structures Developed From Whey-Based ?-Lactalbumin Fractions for Food Applications(John Wiley and Sons Inc., 2014) Tarhan, Özgür; Harsa, ŞebnemWhey proteins have high nutritional value providing use in dietary purposes and improvement of technological properties in processed foods. Functionality of the whey-based α-lactalbumin (α-La) may be increased when assembled in the form of nanotubes, promising novel potential applications subject to investigation. The purpose of this study was to extract highly pure α-La from whey protein isolate (WPI) and whey powder (WP) and to construct protein nanotubes from them for industrial applications. For protein fractionation, WPI was directly fed to chromatography, however, WP was first subjected to membrane filtration and the retentate fraction, whey protein concentrate (WPC), was obtained and then used for chromatographic separation. α-La and, additionally β-Lg, were purified at the same batches with the purities in the range of 95%-99%. After enzymatic hydrolysis, WPI-based α-La produced chain-like and long nanotubules with ∼20 nm width while WPC-based α-La produced thinner, miscellaneous, and fibril-like nanostructures by self-assembly. Raman and FT-IR spectroscopies revealed that α-La fractions, obtained from both sources and the nanostructures, developed using both fractions have some structural differences due to conformation of secondary structure elements. Nanotube formation induced gelation and nanotubular gel network entrapped a colorant uniformly with a transparent appearance. Dairy-based α-La protein nanotubules could be served as alternative gelling agents and the carriers of natural colorants in various food processes.