Irfan Turhan

Ethanol production from carob extract by using Saccharomyces cerevisiae.

Carob has been widely grown in the Mediterranean region for a long time. It has been regarded as only a forest tree and has been neglected for other economical benefits. However, in recent years, this fruit has gained attention for several applications. As petroleum has become depleted, renewable energy production has started to gain attention all over the world; including the production of ethanol from underutilized agricultural products such as carob. In this project, the optimum extraction conditions were determined for the carob fruit by using the response surface design method. The obtained extract was utilized for production of ethanol by using suspended Saccharomyces cerevisiae fermentation. The effect of various fermentation parameters such as pH, media content and inoculum size were evaluated for ethanol fermentation in carob extract. Also, in order to determine economically appropriate nitrogen sources, four different nitrogen sources were evaluated. The optimum extraction condition for carob extract was determined to be 80 degrees C, 2h in 1:4 dilution rate (fruit: water ratio) according to the result of response surface analysis (115.3g/L). When the fermentation with pH at 5.5 was applied, the final ethanol concentration and production rates were 42.6g/L and 3.37 g/L/h, respectively, which were higher than using an uncontrolled pH. Among inoculum sizes of 1%, 3%, and 5%, 3% was determined as the best inoculum size. The maximum production rate and final ethanol concentration were 3.48 g/L/h and 44.51%, respectively, with an alternative nitrogen source of meat-bone meal. Overall, this study suggested that carob extract can be utilized for production of ethanol in order to meet the demands of renewable energy.

Oil production by Mortierella isabellina from whey treated with lactase

Whey, a by-product of cheese manufacturing is rich in nutrients such as lactose, proteins, and mineral salts. The fungus Mortierella isabellina was used for production of oil containing γ-linoleic acid (GLA) during fermentation on deproteinized whey permeate (DP-WP) with and without lactase addition. The maximum oil concentration was 3.65 g/L in DP-whey (16.0% lactose) without enzyme treatment. Treatment of DP-WP with lactase resulted in an increase in oil content to 17.13 g/L. Palmitic (22.50-25.80%) and oleic acids (37.60-48.56%) were the major fatty acids along with GLA (2.18-5.48%), linoleic (16.21-22.43%) and stearic acid (3.20-10.08%). This study suggests that whey can be utilized as a feedstock for production of microbial oil.

Determination of D-pinitol in carob syrup.

Carob syrup is a traditional product native to the Mediterranean region, containing a high concentration of sugar, phenolic compounds and minerals. d-pinitol is a bioactive component extracted from legumes and has some beneficial effects on human metabolism. In this research, the d-pinitol content and sugar profile of 10 different carob syrup samples purchased from Turkish markets were determined. Mean d-pinitol, sucrose, glucose and fructose contents of samples were found to be 84.63 ± 10.73, 385.90 ± 45.07, 152.44 ± 21.72 and 162.03 ± 21.45 g/kg dry weight, respectively. Carob syrup has a considerable amount of d-pinitol compared with the other d-pinitol-including legumes. Consequently, this study showed that carob syrup may be a suitable source of d-pinitol for medical use and d-pinitol may be an indicator for the detection of any adulteration in carob syrup.

Enhanced Lactic Acid Production from Carob Extract by Lactobacillus casei Using Invertase Pretreatment

Carob has been widely grown in the Mediterranean region for centuries. It has been regarded as only a forest tree and has been neglected for other economical benefits. However, in recent years, it has gained attention for several applications. In this study, carob extract has been used as carbon source in fermentation. Lactic acid is considered to be an industrial chemical used in food, textile and pharmaceutical industries. Lactic acid demand has recently increased because of its role as a monomer in the production of biodegradable polylactic acid (PLA), which is known as a sustainable and degradable bioplastic material. Therefore, this study was undertaken to evaluate the potential of carob extract for lactic acid production. Based on our previous study, the optimum extraction conditions were used to obtain the carob extract with high sugar content. Then, obtained extract was utilized by Lactobacillus casei for production of lactic acid by using suspended-cell fermentation. Although carob pod contains 40–50% sugars (especially, sucrose), L. casei could not metabolize them in this complex form. Therefore, sucrose in extract was converted into the monosaccharides by using invertase enzyme prior to fermentation. Also, in order to determine economical appropriate nitrogen sources, four different nitrogen sources were evaluated. The maximum lactic acid concentration and yield for carob extract with yeast extract was 31.35 (g/L) and 68.79% compared with 59.27 (g/L) and 66.70% after using invertase enzyme. Results clearly showed that carob pods can be a good feedstock for lactic acid production by L. casei.

Ultrasound-assisted dilute acid hydrolysis of tea processing waste for production of fermentable sugar.

Lignocellulosic materials that are the most abundant plant biomass in the world have the potential to become sustainable sources of the produced value added products. Tea processing waste (TPW) is a good lignocellulosic source to produce the value added products from fermentable sugars (FSs). Therefore, the present study is undertaken to produce FSs by using ultrasound‐assisted dilute acid (UADA) and dilute acid (DA) hydrolysis of TPW followed by enzymatic hydrolysis. UADA hydrolysis of TPW was optimized by response surface methodology (RSM) at maximum power (900 W) for 2 h. The optimum conditions were determined as 50°C, 1:6 (w/v) solid:liquid ratio, and 1% (w/v) DA concentration, which yielded 20.34 g/L FS concentration. Furthermore, its DA hydrolysis was also optimized by using RSM for comparison and the optimized conditions were found as 120°C, 1:8 solid:liquid ratio, and 1% acid concentration, which produced 25.3 g/L FS yield. Even though the produced sugars with UADA hydrolysis are slightly less, but it can provide significant cost saving due to the lower temperature requirement and less liquid consumption. Besides, enzymatic hydrolysis applied after pretreatments of TPW were very more economic than the conventional enzymatic hydrolysis in the literature due to shorter time requiring. In conclusion, ultrasound‐assisted is a promising technology that can be successfully applied for hydrolysis of biomass and can be an alternative to the other hydrolysis procedures and also TPW can be considered as suitable carbon source for the production of value‐added products like biofuels, organic acids, and polysaccharides.

Relationship Between Sugar Profile and D-Pinitol Content of Pods of Wild and Cultivated Types of Carob Bean (Ceratonia siliqua L.)

Carob has been widely grown in the Mediterranean region for a long time. It has been regarded as only a forest tree and has been neglected for other economic benefits. D-Pinitol is one of the major components in some plants, especially the Leguminosae family. Recently, carob fruit has become more popular because of its D-pinitol content. Therefore, the aim of this study was to evaluate the correlation of sugar profile (glucose, sucrose, and fructose) on the D-pinitol concentration of wild and cultivated types grown in Antalya, Turkey and to compare D-pinitol concentration between both types of carob pods. D-Pinitol concentrations as well as the correlation of sugar profile on it in 32 trees of cultivated and 38 trees of wild carob pods were determined. The results showed that the maximum D-pinitol concentration was 84.59 g/kg in wild type carob pods. Moreover, there was a correlation between sugar profile and D-pinitol for both cultivated and wild types of carob pods.

Ethanol production from rice hull using Pichia stipitis and optimization of acid pretreatment and detoxification processes

The goal of this study was to produce ethanol from rice hull hydrolysates (RHHs) using Pichia stipitis strains and to optimize dilute acid hydrolysis and detoxification processes by response surface methodology (RSM). The optimized conditions were found as 127.14°C, solid:liquid ratio of 1:10.44 (w/v), acid ratio of 2.52% (w/v), and hydrolysis time of 22.01 min. At these conditions, the fermentable sugar concentration was 21.87 g/L. Additionally, the nondetoxified RHH at optimized conditions contained 865.2 mg/L phenolics, 24.06 g/L fermentable sugar, no hydroxymethylfurfural (HMF), 1.62 g/L acetate, 0.36 g/L lactate, 1.89 g/L glucose, and 13.49 g/L fructose + xylose. Furthermore, RHH was detoxified with various methods and the best procedures were found to be neutralization with CaO or charcoal treatment in terms of the reduction of inhibitory compounds as compared to nondetoxified RHH. After detoxification procedures, the content of hydrolysates consisted of 557.2 and 203.1 mg/L phenolics, 19.7 and 21.60 g/L fermentable sugar, no HMF, 0.98 and 1.39 g/L acetate, 0 and 0.04 g/L lactate, 1.13 and 1.03 g/L glucose, and 8.46 and 12.09 g/L fructose + xylose, respectively. Moreover, the base‐line mediums (control), and nondetoxified and detoxified hydrolysates were used to produce ethanol by using P. stipitis strains. The highest yields except that of base‐line mediums were achieved using neutralization (35.69 and 38.33% by P. stipitis ATCC 58784 and ATCC 58785, respectively) and charcoal (37.55% by P. stipitis ATCC 58785) detoxification methods. Results showed that the rice hull can be utilized as a good feedstock for ethanol production using P. stipitis.

Effect of media sterilization and enrichment on ethanol production from carob extract in a biofilm reactor

ABSTRACT In this study, repeated-batch fermentations in a biofilm reactor were evaluated for ethanol production from non-sterile enriched (NSE) and non-sterile non-enriched (NSNE) carob extracts by using Saccharomyces cerevisiae. For the NSE medium, the ethanol production (P) and yield (YP/S) were 18.46 g/L and 33.76%, respectively. However, for the NSNE medium, P and YP/S were 19.57 g/L and 38.14%, respectively. Results indicated that cost-effective ethanol production from non-sterile carob extract (NSCE) can be successfully applied in a biofilm reactor regarding both energy cost and recovery time.

Ethanol production in a biofilm reactor with non-sterile carob extract media and its modeling

ABSTRACT Modeling is gain importance to knowledge about kinetic-metabolic nature of fermentations. In this study, Modified Richards Model (MRM) was applied to model ethanol fermentation in a biofilm reactor with non-sterile carob extract (NSCE). Results indicated that MRM showed its generality to fit cell growth, ethanol production, and sugar consumption curves in non-sterile enriched (NSE) and non-sterile non-enriched (NSNE) media. For NSE medium, MRM successfully predicted the biomass and ethanol production and sugar consumption. Nonetheless, MRM victoriously forecasted all sigmoid curves related to fermentation of NSNE medium. Consequently, MRM predictions satisfactorily fitted the experimental data based on the model evaluation results.

Optimization of acidic hydrolysis conditions of rice husk for fermentable sugar production

ABSTRACT Lignocellulosic biomass (LSB) is the most abundantly available renewable source in the world. Rice husk (RH) is also one of the LSB. In this study, the optimization of dilute acid hydrolysis conditions of RH by using one-factor-at-a-time method was performed. The optimum hydrolysis conditions of RH were determined as 131.04°C, 1:10.28 (w/v) of solid:liquid ratio, 1.47% (w/v) of acid ratio and 24.05 min, which yielded as 25.52 g/L of fermentable sugar concentration. Furthermore, the chemical composition of hydrolysate was also examined and the levels of phenolics, 5-hydroxymethylfurfural (HMF), acetate, glucose, and fructose+xylose were found as 0.89, 0, 3.27, 2.10, and 13.80 g/L, respectively. Accordingly, RH can be utilized as a favorable feedstock for the production of value-added products.