Effects of high hydrostatic pressure (HHP)) on cellulose hydrolysis and cellulase activity, and its use for peanut hulls hydrolysis

---

Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Gıda Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2019

Öğrenci: EYLÜL ÖZTÜRK

Danışman: HAMİ ALPAS

Özet:

High hydrostatic pressure (HHP) technique has potential for food preservation purposes and HHP treatment can inactivate enzymes and/or increase their activity. Avicel, the commercial name of microcrystalline cellulose, is a commonly used substrate to observe the activity of cellulase. Cellulase activity is a crucial parameter for the production of alternative renewable fuels. Celluclast 1.5L, a mixture of enzymes, are used for the hydrolysis of cellulose and hemicellulose containing substances. Peanut hull (35% cellulose) as a lignocellulosic biomass is an appropriate material for conversion of the chemical feedstocks. The aim of this study is to observe different effects of HHP on substrate hydrolysis, and cellulose-hemicellulase (Celluclast) activity. Pressure and time were changed for HHP at the ranges of 0.1500MPa, and 5-15min, respectively, at 30oC. The results showed that hydrolysis of HHP-treated enzyme and HHP-treated enzyme-substrate solutions gave significantly higher reducing sugar content than the non-HHP-treated solution (p<0.05). However, no significant effect was observed between applied pressure levels of 100 and 500MPa (p>0.05). Additionally, the hydrolysis results demonstrated that pretreatment process was a necessary step to increase hydrolysis efficiency due to high lignin content of biomass. According to the Nuclear Magnetic Resonance (NMR) Relaxometry results, significant increases of T2 relaxation were observed with HHP-treated (100 MPa-5 min-30oC) samples due to an increase in hydrophilicity of the sample surface (p<0.05). Additionally, enzymatic hydrolysis led significant increase on the relaxation time (p<0.05). The effects of HHP, alkaline pretreatment and enzymatic hydrolysis were observed with the changes Fourier Transform Infrared (FTIR) spectra.