OPTIMIZATION OF BIOETHANOL PRODUCTION CONDITIONS BY USING EXPIRED AND RETURNED CHOCOLATE PRODUCTS AS SUBSTRATES

In this study, expired and/or returned chocolate products, mainly, couverture chocolate and chocolate sauce were used as substrates for bioethanol production. Box-Benkhen experimental design was employed for the determination of optimum conditions for bioethanol production. The use of both chocolate products as substrates with 20% (w/v) loading without any enzymatic or chemical pretreatment and any addition of nutrients revealed that highest bioethanol yield coefficient Y-PS= 0.50 was obtained based on sugar consumption with chocolate sauce under optimum conditions where 10% (v/v) of inoculum ratio was used, pH 5.50 for 3 days of incubation. On the other hand, the highest bioethanol productivity achieved was 1.13 g/L/h with couverture chocolate where inoculum ratio was 6% (v/v), pH 5.25 for one day of incubation. These results showed that chocolate products could use as effective, economic alternative substrates for bioethanol production

Investigation of lactic acid production by pressurized liquid hot water from cultivated Miscanthus x giganteus

The production of lactic acid, a polylactic acid monomer from energy crop Miscanthus x giganteus lignocellulosic biomass cultivated in Izmir was investigated. Liquid hot water (LHW) pretreatment was carried out at a temperature range of 140-200 degrees C, pressure 100 to 200 bar and reaction time of 15-45 min at a fixed flow rate of 2 mL/min using D-optimal experimental plan. The optimum conditions were elicited as 140 degrees C, 100 bar and 45 minutes, yielding the highest reducing sugar content of 77.32 mg/g, whereas 1.25 mg/mL arabinose and 1.35 mg/mL xylose as monomeric sugars. Subsequently, the enzymatic hydrolysis was applied to the solid fraction. The optimum conditions for enzymatic hydrolysis were determined as 5% (w/v) solid/liquid ratio, 20 FPU/mL enzyme loading and 72 hours, revealing the highest amount of reducing sugar as 200 mg/mL. LHW hydrolysate was used as a production medium for lactic acid manufacturing in submerged fermentation by Rhizopus oryzae. The maximum lactic acid content was found to be 6.8 g/L at 24 hours, whereas the lactic acid yield was 0.28 g/L.h. The sequential design of LHW, followed by enzymatic hydrolysis and submerged lactic acid fermentation can be utilized in industry, contributing to the bioeconomy.This project was supported by Ege University, Scientific Research Projects Coordination (Project Number 17-GEE-008).Ege University, Scientific Research Projects Coordination [17-GEE-008