Browsing by Author "Kahraman, Kevser"

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BUCKWHEAT STARCH-MYRISTIC ACID COMPLEX FORMATION: EFFECT OF REACTION TEMPERATURE AND MYRISTIC ACID CONCENTRATION ON DIGESTIBILITY PROPERTIES
(Prof. Dr. İbrahim ÇAKIR, 2022) OSKAYBAŞ EMLEK, Betül; Ozbey, Ayse; Aydemir, Levent Yurdaer; Kahraman, Kevser; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
This study aimed to investigate the effect of different reaction conditions on the digestibility properties of buckwheat starch-myristic acid complex samples produced using different myristic acid concentrations and different reaction temperatures. Response Surface Methodology was used to investigate the effect of reaction temperature (60-90°C) and fatty acid concentrations (0.1-0.8 mmoL/g) on digestibility properties. Resistant starch (RS) contents of samples increased with an increase in reaction temperature. The reaction temperature affected the rapidly digestible starch (RDS) and slowly digestible starch (SDS) content of samples. The highest RS content (32.57%) was obtained using 0.45 mmoL/g myristic acid at 90°C. The F, p (<0.05), and R2 values indicated that the selected models were significant for the digestibility properties of samples. The complex formation of buckwheat starch with myristic acid seems promising to increase the RS content. Buckwheat appears to have the potential as an RS source, although the studies are quite new yet.
Characteristics of germinated corn flour and influence of germination on cookie properties
(Akademiai Kiado ZRt., 2022) Oskaybaş-Emlek, Betül; Özbey, Ayşe; Kahraman, Kevser; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
The aim of this study was to investigate the effect of germination on the physicochemical, structure, pasting, and morphological properties of corn. Germination improved total phenolic content (TPC) and antioxidant capacity (AC). Scanning electron micrographs (SEM) of flour showed that some starch granule was destroyed with germination. In the same way, pasting values decreased due to changes in the starch granule. FT-IR (Fourier Transform Infrared) spectra confirmed that germination leads to changes in the chemical structure. The XRD (X-ray diffractometer) analysis showed that patterns did not change with germination. In addition, raw and germinated corn flour were used in gluten-free cookie preparation. The cookie dough was evaluated for stickiness. The physical, textural, colour, TPC, and AC of cookie samples were determined. Gluten-free cookies prepared with germinated flour exhibited significantly higher AC due to increase in TPC. Germination could be used to enhance functional properties of corn.
Clarification of Apple Juice Using New Generation Nanocomposite Membranes Fabricated with TiO2 and Al2O3 Nanoparticles
(SPRINGER, ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES, 2020) Severcan, Solmaz Sebnem; Uzal, Nigmet; Kahraman, Kevser; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
To enhance anti-fouling properties of polymeric membranes during apple juice clarification, PSF/PEI (20/2 wt%) ultrafiltration (UF) membranes were modified with TiO2 and Al2O3 nanoparticles using the phase inversion method. Turbid apple juice samples were clarified using cross-flow membrane filtration system. All fabricated nanocomposite UF membranes had higher apple juice flux values than PSF/PEI membrane. Membrane prepared with 0.01% TiO2 (UFT1) had the highest apple juice flux (at steady state, 44.6 L/m(2)h). The FRR (%) value of TiO2 and Al2O3 incorporated UF membranes was between 90.9-94.0% and 79.6-97.6%, respectively, and these FRR values were higher than that of PSF/PEI membrane (UF2, 60.3%). Porosity and hydrophilicity of the UF membranes significantly increased with the addition of nanoparticles and the highest porosity and hydrophilicity was achieved in the 0.01% TiO2 incorporated UF membrane (UFT1) membrane. Higher flux recovery ratio (FRR) and lower relative flux reduction (RFR) values of Al2O3 and TiO2 incorporated nanocomposite membranes, compared with the unmodified membrane, demonstrated the enhancement in the anti-fouling properties of the PSF/PEI membrane. SEM images of the nanocomposite membranes also proved the nanoparticle incorporation to the PSF/PEI matrix. Color, turbidity, total soluble solid, total phenolic content, and antioxidant capacity of the samples using nanocomposite membranes were better than that of clarified using both commercial and unmodified membranes. TiO2 incorporated nanocomposite membranes had superior performance than Al2O3 incorporated nanocomposite membranes and among these membranes, the ones prepared with the addition of 0.01 wt% TiO2 exhibit the best performance in terms of clarification of apple juice.
Clarification of pomegranate juice using PSF microfiltration membranes fabricated with nano TiO(2)and Al2O3
(WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2020) Severcan, Solmaz Sebnem; Uzal, Nigmet; Kahraman, Kevser; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
Microfiltration (MF) membranes were fabricated using PSF/PEI (17/2 wt%) with TiO(2)and Al(2)O(3)nanoparticles to enhance pomegranate juice clarification performance. The membrane performances were tested using dead-end filtration system. Membranes were characterized by Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), porosity, water contact angle, and pure water flux experiments. All MF membranes had higher porosity, pure water flux, and hydrophilicity.SEMimages of the membranes proved the nanoparticle incorporation to the PSF/PEI matrix. The quality of clarified pomegranate juice samples using PSF/PEI nanocomposite membranes were better than that of clarified using both commercial and unmodified membranes. The highest performance for the clarification of pomegranate juice samples was obtained for 0.05% of Al(2)O(3)incorporated PSF/PEI membranes with the highest color (5,781 +/- 4 PtCo), total soluble solid (16.2 +/- 0.0 Brix), total phenolic content (2,642.1 +/- 46.4 mg GAE/L), antioxidant activity (ABTS: 62.4 +/- 0.2 TEAC/L, DPPH: 41.3 +/- 0.0 TEAC/L) and total monomeric anthocyanin (100.7 +/- 1.7 mg/L). Practical applications Utilization of membrane technology in food industry has been increased rapidly in the past two decades. Due to their advantage in terms of saving color pigments, MF membranes are more suitable than UF ones for clarification of pomegranate juice. Incorporation of nanoparticles to the membrane matrix is one of the methods to increase the antifouling character and the strength of the membranes modified with hydrophilic polymers. There are some studies investigating the effect of TiO(2)and Al(2)O(3)nanoparticles on the properties of polymeric membranes. However, there are no reported data on the utilization of TiO(2)and Al(2)O(3)nanocomposite membranes for clarifying pomegranate juice. In this study, TiO(2)and Al(2)O(3)incorporated new generation PSF/PEI membranes were utilized in the clarification process of pomegranate juice for the first time in the literature. The results showed that Al(2)O(3)incorporation seems to be a good alternative for clarifying pomegranate juice with enhanced quality parameters.
Comparative life cycle assessment of retort pouch and aluminum can for ready-to-eat bean packaging
(SPRINGER, 2023) Gulcimen, Sedat; Ozcan, Ozlem; Cevik, Selin Babacan; Kahraman, Kevser; Uzal, Nigmet; 0000-0002-8967-3484; 0000-0002-2786-3944; 0000-0002-0912-3459; AGÜ, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü; Gulcimen, Sedat; Ozcan, Ozlem; Kahraman, Kevser; Uzal, Nigmet
Since packaging contributes to severe environmental impacts in food production, alternatives of packaging materials that satisfy customer needs while minimizing environmental impacts in a cost-effective manner should be preferred for food product sustainability. This paper compares two different packaging materials (aluminum cans and retort pouches) with a life cycle approach to assess the environmental impacts of ready-to-eat bean packaging. The life cycle assessment (LCA) was used to define and compare the environmental performance of ready-to-eat beans in aluminum cans and retort pouches. The gate-to-gate approach was used in the LCA, with a functional unit of 1 kg of packaged ready-to-eat bean product. Inventory for packaging in retort pouch was created in collaboration with Duru Bulgur Company (Karaman, Turkey) and the data for ready-to-eat beans in the aluminum can were gathered from the literature. The findings show that ready-to-eat beans in retort pouches have lower environmental impacts than ready-to-eat beans in aluminum cans. The packaging and washing processes for both ready-to-eat beans packaged in aluminum cans and retort pouches had the greatest environmental impact. In ready-to-eat beans production, retort pouch provides 87% better environmental performance than aluminum can in terms of global warming (GW). Overall, the results demonstrated that replacing aluminum cans with retort pouches in ready-to-eat bean production can significantly reduce environmental effects in all impact categories.
Dietary fibers
(SPRINGER LINK, 2021) Dragan, Simona Ruxanda; Damian, Georgiana; Pah, Ana Maria; Hayta, Mehmet; Kahraman, Kevser; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
Dietary fibers have become increasingly popular in recent years with various applications in the food and pharmaceutical industry industries. Dietary fibers are plant-based foods which are incompletely digested by digestive enzymes. The water-soluble fibers are prebiotics, which are fermented in the colon and have a beneficial role for gut microbiota. The insoluble fibers are not affected by digestive systems and provide bulking. Fiber intake has various benefits: it reduces appetite, lowers variance in blood sugar levels, reduces the risk of cardiovascular disease, lowers the risk of diabetes, balances intestinal pH, alle¬viates constipation, and facilitates regular defecation.
Effect of different resistant starch sources and wheat bran on dietary fibre content and in vitro glycaemic index values of cookies
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND, 2019) Kahraman, Kevser; Aktas-Akyildiz, Eda; Ozturk, Serpil; Koksel, Hamit; 0000-0001-7870-9464; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
Cross-linked starches produced in lab-scale from corn and wheat starches with TDF contents of 80.4% and 83.6% were used in cookie formulation to obtain high fibre and low glycaemic index (GI) cookies. Different resistant starch (RS) sources including and wheat bran were also used for comparison. RS sources were added into the formulation at the levels of 25, 50 and 75%. Overall cookie quality (spread ratio, hardness, colour) results showed that among the RS sources and wheat bran, lab-scale produced cross-linked wheat starch (XL-W) had an improving effect on cookie quality, whereas the other sources had detrimental effect. Cookie samples supplemented with XL-W had the highest total dietary fibre (TDF) contents regardless of the addition level. High levels of TDF content were also observed with the wheat bran supplemented cookie samples; however, quality of these cookies were low. RS and wheat bran supplementation caused significant decrease in the in vitro GI of the cookies and the lowest GI value was achieved with the cookie supplemented with XL-W. This study proved that XL-W produced in this study can be used as an alternative ingredient to produce high fibre and low GI cookies without any deteriorative effect on the quality.
Effects of extrusion cooking on the nutritional quality of puffed snacks made from blends of barley and green lentil flours
(SPRINGER, 2023) Li, Xiang; Franczyk, Adam; Kahraman, Kevser; Koksel, Filiz; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
Increasing demand for nutritionally dense foods warrants the investigation of high fber and protein ingredients in snack food applications. In this study, blends of barley (22.9% dietary fber, db) and green lentil (26.4% protein, db) fours were extruded at fve blending ratios (barley: green lentil, 100: 0, 75: 25, 60: 40, 45: 55, 0: 100, db), two barrel temperature profles (60–130 °C and 70–140 °C from feeder to die) and three feed moisture contents (15, 18 and 21%) to produce pufed snacks. Extrusion signifcantly improved in vitro protein digestibility (IVPD) of all blends by up to 10%. Decreasing feed moisture and increasing die temperature improved IVPD. Blending increased the limiting amino acid score and hence improved the in vitro protein digestibility corrected amino acid score (IVPDCAAS) of extrudates. On average, the blend 45:55 showed the highest average IVPDCAAS (68.62%) among the blends studied and lower glycemic index scores compared to the blend 60: 40. In general, extrusion did not substantially afect the soluble, insoluble or total dietary fber contents of the blends. All extrudates from blends 60: 40 and 45:55 met the requirement to be labelled as “good source of dietary fber” in the US.
Effects of germination on the physicochemical and nutritional characteristics of lentil and its utilization potential in cookie-making
(SPRINGERONE NEW YORK PLAZA, SUITE 4600 , NEW YORK, NY 10004, UNITED STATES, 2021) Oskaybas-Emlek, Betul; Ozbey, Ayse; Kahraman, Kevser; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
Lentil is an alternative gluten-free source with high protein content. In our study, lentil seeds were germinated to enhance the functional and antioxidant properties of lentil. The raw and germinated lentil flour was obtained from lentil seed and used in cookie production. The germination affected the physicochemical, functional, chemical and morphological properties, and pasting behavior of lentil flour. The results indicated that germination caused positive effects on ash and protein content, total phenolic content (TPC), antioxidant properties, oil absorption capacity, and water solubility index. However, germination caused a decrease in the total dietary fiber and starch content due to the activation of the enzymes during germination. SEM images of the germinated lentil flour proved the degradation of starch. Lentil (raw and germinated) flour cookies and wheat flour cookies (Control) were evaluated in terms of physicochemical, TPC, antioxidant properties, textural properties, and in-vitro glycemic index (eGI) value. Germinated lentil flour cookie exhibited the lowest hardness, lightness, yellowness values, the highest TPC and antioxidant activity, and it had the same effect on eGI with control cookie. Overall results indicated that germination can be used as a natural, sustainable, and cost-effective way to improve the functional, and antioxidant properties of lentil. Germinated lentil flour cookie may be considered as a functional food due to high protein content and antioxidant properties.
Effects of resistant starch type 4 supplementation of bread on in vitro glycemic index value, bile acid-binding capacity, and mineral bioavailability
(WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2020) Aribas, Merve; Kahraman, Kevser; Koksel, Hamit; 0000-0002-2786-3944; 0000-0003-4150-2413; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
Background and objectives RS4 is an alternative dietary fiber source with some potential physiological benefits giving better quality end products. Common dietary fiber sources including bran usually have deteriorative effect on color, textural properties, and consumer acceptability of breads. This study was designed to investigate the effect of RS4 supplementation on the bread quality as well as mineral bioavailability, bile acid-binding capacity, in vitro glycemic index. Findings Loaf volumes of the breads supplemented with RS4 were higher than the bread supplemented with wheat bran (WB). Among the bread samples, the one supplemented with WB had the darkest color and highest firmness values. During storage, WB supplementation caused the highest increase in bread firmness. RS4 supplementation caused higher total dietary fiber (TDF) and mineral bioavailability values and lower in vitro glycemic index than bran supplementation. Conclusions RS4 supplementation of bread caused increases in TDF content, bile acid-binding capacity, and mineral bioavailability and has less deteriorative effect on the quality than WB supplementation. Breads supplemented with WB had a faster staling rate than the breads supplemented with RS4. Significance and novelty Besides the better appearance and texture of the RS4 supplemented bread samples, the improvement in nutritional properties proved that RS4 is a better dietary fiber source than WB.
Estimation of Protease Activity by Use of the Mixolab
(ELSEVIER, 2013) Kahraman, Kevser; Koksel, H.; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
It is known that the preharvest attack on wheat by some heteropterous insects (Eurygaster spp., Aelia spp., and Nysius huttoni) reduces the breadmaking quality of the resulting wheat flour (Lorenz and Meredith 1988, Swallow and Every 1991, Harriri et al 2000). The problem is quite common in Mediterranean, Middle Eastern, and East European countries. Before harvest, these insects inject their salivary secretions into maturing wheat ears when they feed. Following attack by the insect, the grain matures normally, but a light-colored opaque patch surrounds the site where the insect pierced the grain. The penetration point is visible as a small dark spot in the middle of this patch. The damaged area is softer and usually collapses when pressed by a fingernail. The secretions contain proteases that break down the gluten structure during mixing and fermentation (Kretovich 1944; Every et al 1998; Sivri et al 1998, 1999).
Formation of resistant starch from amylotype corn starch and determination of the functional properties
(CODON PUBLICATIONS, 2013) Kahraman, Kevser; KÖKSEL, HAMİT; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
High amylose corn starch was hydrolysed with HCl at 40 °C for 0.5-2.0 h. Then the native and acid-modified starch samples were subjected to 2 different heat treatments (HT). In HT1, heat treated/autoclaved samples were dried after storage and in HT2, heat treated/autoclaved samples were dried without storage. Relative quantities of high- and medium-molecular weight fractions decreased and relative quantities of low-molecular weight fractions increased as a result of acid modification. Resistant starch (RS) contents of the acid-modified starches were between 15.7- 16.4% and increased up to 29.4% due to HT1 and up to 17.5% due to HT2. The results indicated that RS contents of the high amylose starch can be increased by HT and storing prior to drying. Rapid ViscoAnalayser viscosity values decreased as the acid modification level increased. Water absorption and solubility values of the samples prepared with both heat treatments were higher than those of the native starch and hydrolysates. Emulsifying capacity/ stability values of soy protein solution supplemented with the hydrolysates and heat treated samples were higher than those supplemented with the native and heat treated native starch.
A functional barley-based fermented soup (tarhana) with high β-glucan content
(SPRINGER, 2025) Koksel, Hamit; Ozkan, Kubra; Tekin-Cakmak, Zeynep Hazal; Karasu, Salih; Kahraman, Kevser; Oruc, Sena; Sagdic, Osman; Sestili, Francesco; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
This study investigates the impact of using different flours, including high beta-glucan barley, on the nutritional properties of tarhana. Mineral composition, phenolic content, and antioxidant capacity of tarhana powder samples produced using flours of high beta-glucan hull-less barley (cv. Chifaa; ChF), hull-less barley cv. Yalin (YF), bread wheat cv. Tosunbey (white flour: TWF1 and whole wheat flour: TWF2). Furthermore, in vitro glycemic index (GI), pasting properties, and RVA soup index of their soups were investigated. Tarhana made with Chifaa barley flour (Tar-ChF) exhibited significantly higher levels of key minerals (K, Mg, Ca), beta-glucan and total phenolic content compared to those made with other flours (Tar YF, Tar TWF1, and Tar TWF2). Barley tarhana samples also showed greater antioxidant activity of bound phenolic fractions and lower GI values, indicating a healthier profile. The study highlights the potential of high beta-glucan barley flour to enhance tarhana's nutritional benefits without significantly affecting its sensory properties, such as color and viscosity. This research supports the integration of health-promoting ingredients like barley flour into traditional Mediterranean foods to improve their nutritional quality.
In vitro glycemic index, bile acid binding capacity and mineral bioavailability of spaghetti supplemented with resistant starch type 4 and wheat bran
(Elsevier Ltd, 2020) Aribas, Merve; Kahraman, Kevser; Köksel, Hamit F.; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü;
In this study effects of resistant starch type 4 (RS4) on nutritional and quality properties of spaghetti were investigated. RS4 was added into spaghetti at different levels (15, 20 and 25%). Wheat bran was also added to spaghetti at 15% level. RS4 supplementation caused lower negative effects on quality properties (total organic matter value, color and textural properties) than bran supplementation. The results point out that RS4 supplementation of spaghetti caused higher total dietary fiber content and comparable glycemic index value at the same bran supplementation level. RS4 caused an increase in bile acid binding capacity and expected to have positive effects on cholesterol metabolism. Moreover, RS4 supplemented spaghetti had generally better mineral bioavailability values compared to bran supplemented and control spaghettis. Overall results indicated that RS4 supplementation provided improvement in nutritional properties of spaghetti and can be an alternative ingredient for fiber supplemented spaghetti compared to bran. © 2020 The Authors
An investigation on the effect of heat-moisture treatment on baking quality of wheat by using response surface methodology
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD24-28 OVAL RD, LONDON NW1 7DX, ENGLAND, 2017) Cetiner, B.; Acar, O.; Kahraman, K.; Sanal, T.; Koksel, H.; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
Effect of heat-moisture treatment on quality properties of two bread wheats (cvs. Tosunbey and Bayraktar) were investigated by using response surface methodology (RSM). Temperature and moisture conditions in the experimental design were in the range of 55-95 degrees C and 13-19%. Heat-moisture treated grains were milled into flour and quality properties were determined. The optimum moisture temperature combination for the highest dry gluten, Zeleny sedimentation, Alveograph W and bread volume values were estimated as 14%-63 degrees C for Tosunbey and 19%-55 degrees C for Bayraktar samples. Alveograph W seems to be a good indicator of baking quality for wheats treated at higher temperatures. In order to describe the relationship between the dependent and independent variables (moisture, temperature), the response values were fitted by second order polynomial models. Significance analysis showed that the effect of both moisture and temperature on dry gluten content, sedimentation and falling number values for Tosunbey; falling number and damaged starch values for Bayraktar were significant (p < 0.05). The effect of temperature on Farinograph water absorption, W and PSG, bread volume and firmness values were significant for both cultivars (p < 0.05). It can be concluded that improvement in baking quality can be achieved and flours with different properties can be produced by heat-moisture treatments on wheat. (C) 2017 Published by Elsevier Ltd.
Karabuğday Nişastasından Yenilebilir Film Üretimi ve Nişastanın Yağ Asitleri ile Modifikasyonunun Film Mekanik Özellikleri Üzerine Etkisi
(TÜBİTAK, 2022) Kahraman, Kevser; Aydemir, Levent Yurdaer; Koca, Esra; Oskaybaş Emlek, Betül; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
Bu proje, karabuğdaydan yüksek saflıkta ve verimde nişasta üretilmesini, üretilen nişastanın çeşitli yağ asitleri (10C, 14C, 18C) kullanılarak elde edilen amiloz-lipit kompleksinden film üretimini amaçlamaktadır. Amiloz-lipit kompleksi üretiminde herbir yağ asidi için en etkili iki reaksiyon parametresi (sıcaklık, süre, pH, yağ asidi/nişasta oranı) belirlenmiştir. Herbir yağ asidi için en etkili iki parametre kullanılarak merkezi kompozit tasarım ile deneme tasarımları oluşturulmuş, komplekslerin kompleks indeks (KI), görünür amiloz, sindirilebilirlik, su bağlama-çözünürlük, çirişlenme, berraklık ve sineresis derecesi gibi özellikleri açısından karakterize edilmiştir. Kompleks oluşumunun nişastanın yapısına etkisi XRD ve FT-IR ile incelenmiştir. Amiloz-lipit kompleks oluşumu ile nişastanın enzime dirençli nişasta miktarı artmış, şişme gücü azalmıştır. En yüksek KI değerine sahip amiloz-kompleksi içeren nişastalar kullanılarak gliserol varlığında filmler üretilmiştir. Gliserol konsantrasyonu, çözelti sıcaklığı ve pH?nın film mekanik özelliklerine etkisinin araştırılması amacıyla, bu parametreler kullanılarak yanıt yüzey yöntemi ile deneme tasarımları oluşturulmuş, film üretimi gerçekleştirilmiş ve optimum film karakteristiklerine sahip film üretiminin sağlandığı parametreler belirlenmiştir. Optimum koşullarda amiloz-lipit kompleksi kullanılarak üretilen filmlerin gerilme dirençleri miristik (1,09 MPa) ve stearik asit (3,360 MPa) için kontrol filme göre daha yüksek, uzama değeri ise kaprik asit (%114,59) için daha yüksek bulunmuştur. Amiloz-lipit kompleksi kullanılarak üretilen filmlerin çözünürlük, nem ve kalınlık değerleri kontrollere göre daha yüksek bulunmuştur. En iyi su buharı bariyer özelliğine amiloz-miristik asit kompleks filmi (0,394 g.mm/m2.h.kPa) ile elde edilmiştir. SEM ve AFM görüntüleri amiloz-lipit kompleksi kullanımının film morfolojik ve topografik özelliklerine etki ettiğini göstermiştir. Su ile yüzey temas açısı sonuçlarına göre sadece amiloz-stearik asit kompleksi filmi hidrofobik yüzeye sahip olmuşlardır. Tüm sonuçlar genel olarak değerlendirildiğinde proje kapsamında karabuğday nişastasından enzime dirençli nişasta kaynağı olma potansiyeline sahip amiloz-lipit kompleksi oluşturmuş; oluşturulan bu komplekslerden mekanik özellikleri yüksek yenilebilir film üretimi gerçekleştirilebilmiştir.
Modelling the Effects of Debranching and Microwave Irradiation Treatments on the Properties of High Amylose Corn Starch by Using Response Surface Methodology
(SPRINGER, 233 SPRING ST, NEW YORK, NY 10013 USA, 2018) Mutlu, Selime; Kahraman, Kevser; Severcan, Sebnem; Ozturk, Serpil; 0000-0002-2786-3944; 0000-0002-3925-9322; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
Response surface methodology was applied to determine the effects of pullulanase debranching, microwave irradiation time (2-4 min) and power (20-100%) on resistant starch (RS) formation and in-vitro glycemic index (GI) values in high amylose corn starch, Hylon VII. Starch:water (1:10) suspensions were cooked and autoclaved, debranched with pullulanase (1000 PUN/g; 1500 U/kg starch) at 60 A degrees C and then different microwave-storing cycles and drying (oven or freeze drying) processes were applied. In order to describe the relationship between the dependent and independent variables (microwave power and irradiation time), the response values were fitted by first order polynomial regression models. Significance analysis showed that microwave irradiation time had significant effect on RS content and GI value of the samples treated with one cycle of microwave-storing prior to freeze-drying. Microwave power had significant factor on the GI value of the samples that were oven-dried after one cycle of microwave-storing. Solubility and water binding capacity values of all heat treated samples were higher than those of native starch. On the other hand, RVA viscosity values were lower than native starch for oven-dried samples. Water binding capacity, solubility and final viscosity values of the freeze-dried samples were higher than those of oven-dried ones.
Nişasta Nanokristali Üretimi ve Karakterizasyonu
(Osman Sağdıç, 2019) Korkut, Ayşe; Kahraman, Kevser; 0000-0002-8823-2089; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Korkut, Ayşe; Kahraman, Kevser
Bu çalışmada nano malzeme üretimi konusunda doğal ve yenilenebilir bir kaynak olarak son yıllarda oldukça ilgi çeken birhammadde olan nişastadan yüksek kristaliniteye sahip nanokristal üretimi hedeflenmiştir. Bu amaçla buğday nişastası farklı oranlardaH2SO4 (1:2 ve 1:4 nişasta:asit) ile beş gün boyunca 50℃ sıcaklıkta hidroliz edilmiştir. Hidroliz sonrasında örnekler diyalize tabitutularak safsızlıklar giderilmiş, liyofilize edilerek kurutulmuştur. Elde edilen nişasta nanokristalleri taramalı elektron mikroskobu(SEM) kullanılarak boyut; X-Işını Kırınım Spektroskopisi (XRD) kullanılarak yapı ve kristalinite; Fourier dönüşümlü kızılötesispektrometresi (FT-IR) kullanılarak yapı açısından karakterize edilmiştir. Doğal haldeki buğday nişastası da aynı şekilde karakterizeedilmiş ve hidroliz işleminin yapı, boyut ve kristalinite üzerine etkisi incelenmiştir.SEM görüntüleri incelendiğinde buğday nişastasının boyutlarının 5-10 µm arasında değişim gösterdiği belirlenmiştir. Asit hidrolizisonucunda ise nişasta boyutunun oldukça azaldığı ve 50 nm’nin altına düştüğü gözlenmiştir. Doğal haldeki buğday nişastasıbirbirinden bağımsız granüller halinde iken nişasta nanokristalleri kümeleşmiş halde görüntülenmiştir. XRD desenleri incelendiğindeasit hidrolizi ile elde edilen nişasta nanokristallerin buğdayın tipik X-ışını kırınım deseni olan A-tipi X-ışını kırınım desenini verdiğigözlenmiştir. X-ışını kırınım desenleri yapı açısından incelendiğinde işlem görmemiş doğal haldeki buğday nişastası ile nişastananokristallerin arasında fark görülmese de, bu örneklerin kristalinite indeks değerlerinin farklı olduğu belirlenmiştir. Doğal haldekibuğday nişastasının kristalinite indeks değeri %42,2 olarak belirlenmişken, asit hidrolizi ile üretilen nişasta nanokristallerininkristalinite indeks değerleri daha yüksek bulunmuştur. Düşük oranda asit kullanılarak üretilen nişasta nanokristalinin (1:2) kristaliniteindeks değeri %57,3 iken daha yüksek oranda kullanılarak üretilen nişasta nanokristalininin (1:4) kristalinite indeks değeri %68,5olarak belirlenmiştir. FT-IR sonuçlarına göre ise nişasta nanokristallerin doğal buğday nişastası ile aynı yapıya sahip olduğugözlemlenmiştir.
A Novel high-amylose wheat-based functional cereal soup (tarhana) with low glycemic index and high resistant starch
(Academic Press, 2024) Koksel, Hamit; Tekin-Cakmak, Zeynep Hazal; Ozkan, Kubra; Pekacar, Zeynep; Oruc, Sena; Kahraman, Kevser; Ozer, Cagla; Sagdic, Osman; Sestili, Francesco; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
This study investigated the potential of high-amylose wheat flour (Svevo-HA) to enhance the dietary profile of tarhana, a traditional Mediterranean fermented cereal yogurt mixture. The moisture content of tarhana powders ranged from 7.81% to 11.64%. Color parameters varied depending on the type of flour used, with Svevo-HA samples demonstrating decreased L* values and increased a* and b* values. Mineral compositions differed significantly among tarhana samples, with higher levels of K, Mg, Mn, Fe, Cu, and Zn observed in samples prepared with Svevo-HA. Gallic acid was identified as the major phenolic compound in all the tarhana samples for free fraction, while ferulic acid was determined as the major phenolic compound for its bound form. Supplementation of tarhana soups with heat-treated Svevo-HA flour increased the resistant starch content and decreased in vitro glycemic index value compared to soups prepared with conventional wheat flour. These findings highlight the potential of utilizing Svevo-HA flour to develop healthier versions of traditional foods.
Optimisation of the reaction conditions for the production of cross-linked starch with high resistant starch content
(ELSEVIER SCI LTD, 2015) Kahraman, Kevser; Koksel, Hamit; Ng, Perry K. W.; 0000-0002-2786-3944; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Kahraman, Kevser
The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and wheat starches with maximum resistant starch (RS) content were investigated by using response surface methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature (38–70 C) and pH (10–12) in the main study. RS contents of the CL corn and wheat starch samples increased with increasing temperature and pH, and pH had a greater influence on RS content than had temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch cross-linked at 38 C and pH 12. In the case of CL corn starch, the optimum condition was 70 C and pH 12. CL corn and wheat starch samples were also produced separately under the optimum conditions and their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the values predicted by RSM.