Food Engineering / Gıda Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/12
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Article Citation - WoS: 19Citation - Scopus: 20Processing of Hazelnut (corylus Avellana L.) Shell Autohydrolysis Liquor for Production of Low Molecular Weight Xylooligosaccharides by Aureobasidium Pullulans Nrrl Y-2311 Xylanase(Elsevier, 2021) Sürek, Ece; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; Yeğin, Sırma; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, a versatile process for the production of xylooligosaccharides (XOS) with a low degree of polymerization (DP 2-6) from hazelnut shells was designed. This process included autohydrolysis integrated with sequential enzymatic hydrolysis by crude xylanase produced with Aureobasidium pullulans NRRL Y-2311-1 from wheat bran. Autohydrolysis of hazelnut shells was carried out at a solid:liquid ratio of 1:6 (w/w) and 190 degrees C nonisothermally. The effects of several parameters on enzymatic hydrolysis of the autohydrolysis liquor were determined. The maximum XOS (DP 2-6) production was 22.5 g/L which was obtained at pH 5.0 and 40 degrees C using enzyme concentration of 240 U/g XOS and substrate concentration of 72 g/L. Under these conditions, 31.29 % of the substrate (total XOS) was converted to low-DP-XOS; xylobiose and xylotriose are being the major oligomers. This is the first study on the application of A. pullulans xylanase in production of xylooligomers from hazelnut shells.Article Mikrobiyal Ksilanazlar ve Gıda Endüstrisinde Kullanım Alanları(Sidas Medya Ajans Tanıtım Danışmanlık Ltd. Şti., 2015) Yeğin, Sırma; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyKsilanazlar, doğada bitki hücre duvarının yapısında bulunan ksilanın hidrolizini sağlayan enzimlerdir. Çok yaygın kullanım alanı bulunan bu enzimler gıda ve yem sektörü açısından da büyük önem taşımaktadırlar. Endüstriyel ksilanaz üretimi mikrobiyal biyoproseslerle gerçekleştirilmektedir. Söz konusu enzimlerin biyosentez düzeyi, biyokimyasal ve teknolojik özellikleri, üretimde kullanılan mikroorganizma ve biyoproses koşullarına göre farklılık göstermektedir. Son zamanlarda ksilanazların üretim düzeylerinin arttırılması, saflaştırılması ve karakterizasyonu üzerinde çok sayıda çalışma yapılmıştır. Ancak günümüzde sürdürülebilir, çevreci ve ekonomik proseslerin geliştirilmesi adına alışılmışın dışında ve çok yönlü kullanılabilen yeni enzim sistemlerine ihtiyaç vardır. Bu derlemede, ksilanın yapısı, ksilanaz grubu enzimlerin sınıflandırılması, mikrobiyal ksilanaz üretimi, saflaştırılması, karakterizasyonu ve gıda sektöründe uygulamaları üzerinde durulmuştur.Article Utilization of White Grape Pomace for Lactic Acid Production(Gıda Teknolojisi Derneği, 2018) Bayrak, Emrah; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyBeyaz 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 önlenmelidirArticle Kritik Altı Su ile Fındık Atıklarından Antioksidan Bileşiklerin Ekstraksiyonu(Gıda Teknolojisi Derneği, 2018) Sürek, Ece; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyTürkiye fındık üretim ve ihracatında dünya lideridir. Fındığın tarımı ve işlenmesi sırasında büyük miktarda kabuk, zuruf ve dal gibi atıklar açığa çıkmaktadır. Bu atıkların çevre dostu bir teknoloji ile işlenmesi ve önemli ürünlerin üretilmesi katma değer sağlayabilir. Bu çalışmada, fındık atıklarının farklı sıcaklık (150-200?C) ve sürelerde (0-45 dk) kritik altı su ekstraksiyonu ile elde edilen likörlerinin toplam fenolik madde içeriği (TFİ) ve toplam antioksidan aktiviteleri (TAA) incelenmiştir. Genel olarak, kritik altı su ekstraksiyonu ile aseton ve metanol ekstraksiyonuna göre daha yüksek verim elde edilmiştir. Sıcaklık arttıkça fındık kabuğundan elde edilen TFİ ve TAA artmıştır. Süre artışı 180?C'de istatistiksel olarak önemli bir fark yaratmazken, 190?C'de TFİ süre arttıkça yükselmiştir (P <0.05). Bu iki koşulun fındık kabuğu üzerine etkisi şiddet faktörünün logaritmik değeri (log Ro) hesaplanarak tek bir parametrede de incelenmiştir. log Ro arttıkça TFİ (905.3-2115.7 mg GAE/100 g kabuk) ve TAA (8163.9-12261.5 mg TE/100 g kabuk) değerleri yükselmiştirArticle Citation - WoS: 1Citation - Scopus: 1Temperature and Glycerol Formation: a Proposal To Explain the Causal Relationship Based on Glycolytic Enzyme Activities(American Society for Enology and Viticulture, 2019) Büyükkileci, Ceylan; Batur, Ayşem; Büyükkileci, Ali Oğuz; Hamamcı, Haluk; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyMost yeast strains produce glycerol in larger quantities when cultivated at higher temperatures, which likely explains why red wines contain higher amounts of glycerol than white wines. In this work, we used a kinetic and thermodynamic approach to suggest a mechanistic explanation for this phenomenon. We began with a glycolytic model of the kinetics of the individual enzymes. The effects of temperature and ethanol on the apparent kinetics of individual enzymes were then determined and incorporated into the model. The activation energy for each enzyme was determined with the Arrhenius equation. The enzymes in the upper part of the glycolytic pathway were found to be more dependent on the temperature than those in the lower part. The model, as improved by these changes, could qualitatively simulate the ethanol and glycerol production curves and the production of more glycerol at higher temperatures. We propose that the differences in the temperature dependence of the enzymes around the glycerol branch are the reason for glycerol accumulation at higher temperatures.Article Citation - WoS: 73Citation - Scopus: 77Utilization of Xylan-Type Polysaccharides in Co-Culture Fermentations of Bifidobacterium and Bacteroides Species(Elsevier, 2020) Zeybek, Nüket; Rastall, Robert A.; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyAlthough most members of the genus Bifidobacterium are unable to utilize xylan as a carbon source, the growth of these species can be induced by this polysaccharide in the gut environment. This indicates a requirement for an association between Bifidobacterium species and some other members of gut microbiota. In this study, the role of cross-feeding between Bifidobacterium and Bacteroides species in the bifidogenic effect of xylan was investigated using in-vitro pure and co-culture fermentations. The pure culture studies showed that among the Bifidobacterium species tested, only Bifidobacterium animalis subsp. lactis was able to utilize xylooligosaccharides. The co-culture of this strain with Bacteroides species enabled it to grow in the presence of xylan. These results suggest that the ability of Bacteroides species to hydrolyze xylan could allow the proliferation of specific Bifidobacterium species in the gut through substrate cross-feeding.Article Citation - WoS: 40Citation - Scopus: 45Comparison of Liquid Hot Water, Very Dilute Acid and Alkali Treatments for Enhancing Enzymatic Digestibility of Hazelnut Tree Pruning Residues(Elsevier, 2018) Sabancı, Kevser; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe effect of pretreatments on the composition of the hazelnut tree pruning residue (HTPR) and on the digestibility of the cellulose was investigated. The liquid hot water (LHW) and the very dilute acid (VDA) treatments were effective in solubilizing hemicellulose. The cellulose conversion increased up to around 60% (corresponding to 32–36 g/L glucose) with decreasing hemicellulose concentration in the pretreated HTPR. The alkali treatment provided partial delignification, however, the glucose production was comparably lower. Combining the hemicellulose removal and the delignification effect of different pretreatments in two-stage processes (LHW-alkali and VDA-alkali treatments) enhanced the cellulose concentration in the solids, but not the amount of glucose released in the enzymatic digestion. These results suggested that the hemicellulose was the main barrier against the conversion of cellulose in the LHW and VDA treated HTPR and the glucose in the hydrolysis medium inhibited the cellulase activity, which prevented the complete conversion of cellulose.Article Citation - WoS: 112Citation - Scopus: 132Production of Xylooligosaccharides by Autohydrolysis of Hazelnut (corylus Avellana L.) Shell(Elsevier Ltd., 2017) Sürek, Ece; Büyükkileci, Ali Oğuz; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyHazelnut shell (HS), husk and pruning residues were characterized and evaluated for xylooligosaccharides (XOS) production by autohydrolysis. HS contained the highest amount of xylan and yielded more XOS compared to other hazelnut residues. The temperature and holding time of HS autohydrolysis greatly influenced the composition of the liquor and the remaining solid. The highest XOS yield (62% of the feedstock xylan) was obtained at 190 °C and 5 min of holding time. At this temperature, 30 min of holding time was required to maximize the percentage of XOS with low degree of polymerization. Xylose, acetic acid and furfural concentrations increased with treatment severity. The concentrations of the products in the autohydrolysis liquors followed specific trends with changing severity factor (log Ro) values. Solubilization of xylan in the treatments enhanced the cellulose and lignin contents in the remaining solids.Article Citation - WoS: 33Citation - Scopus: 34Exploitation of Agricultural Wastes and By-Products for Production of Aureobasidium Pullulans Y-2311 Xylanase: Screening, Bioprocess Optimization and Scale Up(Springer Verlag, 2017) Yeğin, Sırma; Büyükkileci, Ali Oğuz; Sargın, Sayıt; Göksungur, Yekta; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe potential of several agricultural wastes and by-products (wheat bran, oat bran, corn cob, brewer’s spent grain, malt sprout, artichoke stem, sugar beet pulp, olive seed, cotton stalk and hazelnut skin) was examined as the substrate for xylanase production by Aureobasidium pullulans Y-2311-1. Based on the screening studies, wheat bran was selected as the best substrate for further optimization studies. The effects of initial medium pH, temperature and incubation time on xylanase production in shake flask system were optimized by response surface methodology (RSM). The optimum levels of the process variables defined by the model (initial medium pH, 4.24; temperature, 30.27 °C; and incubation time 126.67 h) resulted in production of 85.19 U/ml xylanase. Taking the RSM optimized parameters in shake-flask scale into consideration; xylanase production was scaled up to bioreactor system with a working volume of 1.5 l. The peak of enzyme production was achieved after 126 h incubation that has previously been determined by RSM studies at shake flask level. Furthermore, the optimum levels of agitation and aeration in bioreactor system was found as 200 rpm and 1.5 vvm. Maximum enzyme production was close to 85 kU/l which could be translated into a productivity of 0.68 kU/l/h. No previous work considered the statistical optimization of xylanase production by A. pullulans on wheat bran and scale up of the bioprocess to a bioreactor systemArticle Citation - WoS: 12Citation - Scopus: 16Utilization of Orange Peel, a Food Industrial Waste, in the Production of Exo-Polygalacturonase by Pellet Forming Aspergillus Sojae(Springer Verlag, 2015) Büyükkileci, Ali Oğuz; Lahore, Marcelo Fernandez; Tarı, Canan; Büyükkileci, Ali Oğuz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe production of exo-polygalacturonase (exo-PG) from orange peel (OP), a food industrial waste, using Aspergillus sojae was studied in submerged culture. A simple, low-cost, industrially significant medium formulation, composed of only OP and (NH4)2SO4 (AS) was developed. At an inoculum size of 2.8 × 103 spores/mL, growth was in the form of pellets, which provided better mixing of the culture broth and higher exo-PG activity. These pellets were successfully used as an inoculum for bioreactors and 173.0 U/mL exo-PG was produced. Fed-batch cultivation further enhanced the exo-PG activity to 244.0 U/mL in 127.5 h. The final morphology in the form of pellets is significant to industrial fermentation easing the subsequent downstream processing. Furthermore, the low pH trend obtained during this fermentation serves an advantage to fungal fermentations prone to contamination problems. As a result, an economical exo-PG production process was defined utilizing a food industrial by-product and producing high amount of enzyme.