Prebiyotik içeren inek sütü üretimi için aspergıllus oryzae ß-galaktozıdazın karboksile çok duvarlı karbon nanotüpler ile immobilizasyonu
[ X ]
Tarih
2019
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Siirt Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tez çalışmasında, Aspergillus oryzae ?-Galaktozidaz (AOG), ticari immobilizasyon matrisi olan karboksillenmiş çok duvarlı karbon nanotüpler (c-MWCNT) üzerine adsorpsiyon yöntemiyle immobilize edildi. İmmobilizasyon koşullarının (immobilizasyon tamponunun pH ve molaritesi, c-MWCNT miktarı ve immobilizasyon süresi) optimizasyonu sonucunda, % 100.00 immobilizasyon verimi ve % 155.00 aktivite verimi elde edildi. Ayrıca, serbest ve immobilize AOG'un karakterizasyonu da çalışıldı. AOG'un optimum pH aralığı (4.5-6.5) ve optimum sıcaklığı (55 oC) immobilizasyon sonrasında değişmedi. Lineweaver-Burk grafiğinden, serbest ve immobilize AOG için Km değerlerinin sırasıyla, 31.95 g laktoz / L ve 20.28 g laktoz / L olarak, Vmax değerlerinin ise sırasıyla, 10.36 ?mol indirgen şeker / mg.dk ve 16.10 ?mol indirgen şeker / mg.dk olarak hesaplandı. Öte yandan, immobilize AOG, peş peşe tekrarlanan yirmi kullanım sırasında ve optimum koşullarda (+4 oC'deki bir buzdolabında, pHsı 4.5 olan 5 mL 25 mM sodyum asetat tamponunda) yirmi günlük depolama sırasında, başlangıç aktivitesini kaybetmedi. Son olarak, immobilize AOG kullanılarak, 55 oC'de yarım yağlı UHT inek sütündeki laktoz süt içerisinde kısmen galaktooligosakkaritlere (GOS) dönüştürüldü. Başlangıçtaki % 4.70 (w/v) olan laktozun, 240 dakika süren reaksiyon sonunda % 2.78 (w/v)'e düşerken, laktoz'dan % 1.79 (w/v) oranında GOS oluştuğu ve % 0.13 (w/v) oranında da monosakarit salındığı belirlendi. Buna göre laktozun % 38.09 (w/w)'unun GOS'a dönüştüğü anlaşıldı. Sonuç olarak, bu tez çalışmasında elde edilen c-MWCNT üzerine immobilize AOG'un, endüstriyel olarak süt içerisindeki laktozdan GOS üretiminde kullanılabileceği söylenebilir.
In this study, Aspergillus oryzae ?-Galactosidase (AOG) was immobilized by adsorption on carboxylated multi-walled carbon nanotubes (c-MWCNT), a commercial immobilization martix. The optimization of immobilization conditions (pH and molarity of immobilization buffer, c-MWCNT amount and immobilization time) resulted in 100.00% immobilization yield and 155.00% activity yield. In addition, characterization of free and immobilized AOG was studied. The optimum pH range (4.5-6.5) and optimum temperature (55 oC) of AOG did not change after immobilization. From Lineweaver-Burk plot, Km values for free and immobilized AOG were calculated as 31.95 g lactose / L and 20.28 g lactose / L, while Vmax values were 10.36 ?mol reducing sugar / mg.dk and 16.10 ?mol reducing sugar / mg.dk, respectively. On the other hand, immobilized AOG did not lose its initial activity during twenty consecutive repeated uses and twenty days of storage under optimum conditions (in 5 mL of 25 mM sodium acetate buffer pH 4.5 in a refrigerator at +4 °C). Finally, using immobilized AOG, lactose in semi-skimmed UHT cow's milk was partially converted to galactooligosaccharides (GOS) at 55 oC. Finally, using immobilized AOG, the lactose in half-fat UHT cow milk at 55 oC was partially converted to galactooligosaccharides (GOS) in milk. The initial lactose, which was 4.70% (w/v), decreased to 2.78% (w/v) at the end of the reaction for 240 minutes, while 1.79% (w/v) GOS formed from lactose and 0.13% (w/v). monosaccharide was released. Accordingly, it was found that 38.09% (w/w) of lactose was converted to GOS. Consequently, it can be said that the immobilized AOG on c-MWCNT obtained in this thesis can be used industrially in the production of GOS from lactose in milk.
In this study, Aspergillus oryzae ?-Galactosidase (AOG) was immobilized by adsorption on carboxylated multi-walled carbon nanotubes (c-MWCNT), a commercial immobilization martix. The optimization of immobilization conditions (pH and molarity of immobilization buffer, c-MWCNT amount and immobilization time) resulted in 100.00% immobilization yield and 155.00% activity yield. In addition, characterization of free and immobilized AOG was studied. The optimum pH range (4.5-6.5) and optimum temperature (55 oC) of AOG did not change after immobilization. From Lineweaver-Burk plot, Km values for free and immobilized AOG were calculated as 31.95 g lactose / L and 20.28 g lactose / L, while Vmax values were 10.36 ?mol reducing sugar / mg.dk and 16.10 ?mol reducing sugar / mg.dk, respectively. On the other hand, immobilized AOG did not lose its initial activity during twenty consecutive repeated uses and twenty days of storage under optimum conditions (in 5 mL of 25 mM sodium acetate buffer pH 4.5 in a refrigerator at +4 °C). Finally, using immobilized AOG, lactose in semi-skimmed UHT cow's milk was partially converted to galactooligosaccharides (GOS) at 55 oC. Finally, using immobilized AOG, the lactose in half-fat UHT cow milk at 55 oC was partially converted to galactooligosaccharides (GOS) in milk. The initial lactose, which was 4.70% (w/v), decreased to 2.78% (w/v) at the end of the reaction for 240 minutes, while 1.79% (w/v) GOS formed from lactose and 0.13% (w/v). monosaccharide was released. Accordingly, it was found that 38.09% (w/w) of lactose was converted to GOS. Consequently, it can be said that the immobilized AOG on c-MWCNT obtained in this thesis can be used industrially in the production of GOS from lactose in milk.
Açıklama
Fen Bilimleri Enstitüsü, Gıda Mühendisliği Ana Bilim Dalı
Anahtar Kelimeler
Gıda Mühendisliği, Food Engineering
