Publication: Fermentation of enzymatically saccharified agricultural residues for ethanol production
Abstract
ENZİMATİK YOLLARLA HİDROLİZLENMİŞ TARIMSAL ATIKLARIN FERMENTASYONU İLE ETANOL ÜRETİMİ Bu çalışmada, biyoetanol üretimi için Türkiye’de bol miktarda üretilen fındığın kullanılabilirliği araştırılmıştır. Fındığın zurufu ve iç kabuğu değişik koşullarda hidrolizlenerek, en yüksek şeker miktarının elde edileceği koşullar incelenmiştir. Fındık zurufu ve iç zarı öğütülerek, farklı sürelerde (30 dk - 90dk), farklı sülfürik asit konsantrasyonlarında (kütlece, %1 - %5) ve farklı örnek konsantrasyonlarında (1/ 5, 1/ 10, 1/ 15, 1/ 20, katı/ sıvı oranı) sülfürik asitle muamele edilmiştir. En yüksek şeker verimi 18.63 ±0.51% (g indirgen şeker/ g kuru kütle %), fındık zurufunun % 4 asit konsantrasyonu ve 1/ 20 örnek konsantrasyonunda 1.5 saat hidrolizi sonucunda elde edilmiştir. Asit ile hidrolizlenmiş fındık zurufunun şeker bileşimi TLC (İnce Tabaka Kromatografisi) kullanılarak tespit edilmiştir. Fındık zurufu hidrolizatında arabinoz, glukoz, mannoz ve ksiloz olmak üzere dört monosakkarit belirlenmiştir. Fındık zurufu ayrıca, selulaz enzimi ile de hidrolizlenmiştir. Substrat konsantrasyonunun enzimatik hidroliz üzerine etkisi, değişik örnek konsantrasyonları (0.03 – 0.07 g/ mL) kullanılarak incelenmiştir. Şeker verimini arttırmak amacı ile ayrıca, enzimatik hidrolizden önce, farklı sürelerde (30dk-90dk) buhar ön işlemi ve asit hidrolizi de uygulanmıştır. En yüksek şeker verimi, 5.5 g/ L, asit hidrolizlenmiş enzimatik hidroliz ile elde edilmiştir. Fındık iç zarı için en yüksek şeker verimi, 8.3 ±2.35% (g indirgen şeker/ g kuru kütle %) ise 1% acid konsantrasyonu ve 1/ 20 örnek konsantrasyonunda 1.0 saat hidroliz sonucunda elde edilmiştir. Hidroliz edilmiş fındık iç zarı örneklerindeki şeker bileşimi HPLC (Shimadzu Corporation, Kyoto, Japan) kullanılarak analiz edilmiştir. Hidroliz edilmiş fındık iç zarı örneklerinde başlıca üç monosakkarit; arabinoz, glukoz ve fruktoz belirlenmiştir. Hidroliz çözeltilerinden etanol üretimi, S.cerevisiae FY23 kullanılarak incelenmiş ve en iyi etanol verimi, 7.65 g/ L, fındık zurufunun asit ile hidrolizinden elde edilen hidroliz çözeltisinin fermentasyon ortamında karbon kaynağı olarak kullanılması ile elde edilmiştir.
FERMENTATION OF ENZYMATICALLY SACCHARIFIED AGRICULTURAL RESIDUES FOR ETHANOL PRODUCTION In order to obtain a better exploitation of raw material for bioethanol production, the most favorable conditions were explored for saccharification of the residues of hazelnut, an abundant agricultural product in Turkiye. Hazelnut husk and hazelnut skin were pulverized and treated with sulphuric acid. Different times of treatment (30 min-90 min), different concentrations of sulphuric acid (1% to 5%, by wt) and different concentrations of sample (1/ 5, 1/ 10, 1/ 15, 1/ 20 solid/ liquid ratio) were tested. The maximum yield of sugar (g reducing sugar/ g dry mass %) was obtained as 18.63 ±0.51% for 1.5 hour incubation at an acid concentration of 4% and a sample concentration of 1/ 20 for hazelnut husk. The sugar composition of hydrolysed hazelnut husk was analysed using Thin Layer Chromatography (TLC). Four mono-sugars, arabinose, glucose, mannose and xylose were determined in acid hydrolyzed hazelnut husk. Hazelnut husk were also saccharified by cellulase enzyme. Different sample concentrations (0.03-0.07 g/ ml) were used to determine the effect of substrate concentration on enzymatic saccharification. The effect of steam pretreatment at different time intervals (30 min - 90 min) and acid hydrolysis on enzymatic hydrolysis were also investigated. The maximum yield of sugar as 5.5 g/ L was obtained for acid hydrolyzed enzymatic hydrolysis. For hazelnut skin, the maximum yield of sugar as 8.3 ± 2.35 % (g reducing sugar/ g dry mass %) was obtained for 1.0 hour incubation at an acid concentration of 1% and a sample concentration of 1/ 20. Sugar compositions of hydrolyzed samples were analyzed by using HPLC (Shimadzu Corporation, Kyoto, Japan) with Fast Carbohydrate Analyses Column (100 x 7.8, Bio- Rad) and three major mono-sugars; arabinose, glucose and fructose were identified in the hydrolyzed hazelnut skin. Hydrolyzates obtained after saccharification were used in ethanol production by S.cerevisiae. The highest ethanol yield as 7.65 g/ L was obtained using acid hydrolyzate of hazelnut husk.
FERMENTATION OF ENZYMATICALLY SACCHARIFIED AGRICULTURAL RESIDUES FOR ETHANOL PRODUCTION In order to obtain a better exploitation of raw material for bioethanol production, the most favorable conditions were explored for saccharification of the residues of hazelnut, an abundant agricultural product in Turkiye. Hazelnut husk and hazelnut skin were pulverized and treated with sulphuric acid. Different times of treatment (30 min-90 min), different concentrations of sulphuric acid (1% to 5%, by wt) and different concentrations of sample (1/ 5, 1/ 10, 1/ 15, 1/ 20 solid/ liquid ratio) were tested. The maximum yield of sugar (g reducing sugar/ g dry mass %) was obtained as 18.63 ±0.51% for 1.5 hour incubation at an acid concentration of 4% and a sample concentration of 1/ 20 for hazelnut husk. The sugar composition of hydrolysed hazelnut husk was analysed using Thin Layer Chromatography (TLC). Four mono-sugars, arabinose, glucose, mannose and xylose were determined in acid hydrolyzed hazelnut husk. Hazelnut husk were also saccharified by cellulase enzyme. Different sample concentrations (0.03-0.07 g/ ml) were used to determine the effect of substrate concentration on enzymatic saccharification. The effect of steam pretreatment at different time intervals (30 min - 90 min) and acid hydrolysis on enzymatic hydrolysis were also investigated. The maximum yield of sugar as 5.5 g/ L was obtained for acid hydrolyzed enzymatic hydrolysis. For hazelnut skin, the maximum yield of sugar as 8.3 ± 2.35 % (g reducing sugar/ g dry mass %) was obtained for 1.0 hour incubation at an acid concentration of 1% and a sample concentration of 1/ 20. Sugar compositions of hydrolyzed samples were analyzed by using HPLC (Shimadzu Corporation, Kyoto, Japan) with Fast Carbohydrate Analyses Column (100 x 7.8, Bio- Rad) and three major mono-sugars; arabinose, glucose and fructose were identified in the hydrolyzed hazelnut skin. Hydrolyzates obtained after saccharification were used in ethanol production by S.cerevisiae. The highest ethanol yield as 7.65 g/ L was obtained using acid hydrolyzate of hazelnut husk.