Laboratory scale optimization of alkali pretreatment for improvingenzymatic hydrolysis of sweet sorghum bagasse

Sweet sorghum has been identified as a promising feedstock for biological conversion to fuels as wellas other chemicals. The lignocellulosic stalk of sweet sorghum, called sweet sorghum bagasse (SSB) isa potential source of lignocellulosic biofuel. The primary goal of this study was to determine optimalalkali (lime: Ca(OH)2and lye: NaOH) pretreatment conditions to obtain higher yield of total reducingsugar while reducing the lignin content for biofuel production from SSB. Biomass conversion and ligninremoval were simultaneously optimized through four quadratic models analyzed by response surfacemethodology (RSM). The optimal conditions for lime pretreatment was 1.7% (w/v) lime concentration,6.0% (w/v) SSB loading, 2.4 h pretreatment time with predicted yields of 85.6 total biomass conversionand 35.5% lignin reduction. For lye pretreatment, 2% (w/v) alkali, 6.8% SSB loading and 2.3 h durationwere the optimal levels with predicted biomass conversion and lignin reduction of 92.9% and 50.0%,respectively. More intensive pretreatment conditions removed higher amounts of hemicelluloses andcellulose. Fourier transform infrared spectroscopy (FTIR) spectrum and scanning electron microscope(SEM) image revealed compositional and microstructural changes caused by the alkali pretreatment

Efficacy of limonene nano coatings on post-harvest shelf life of strawberries

Strawberries are highly demanded fruits because of their color, nutritional values and appearance. The aim of this study was to develop and characterize alginate and limonene liposomes as edible coating materials and to determine their efficacy in shelf life extension and maintaining quality parameters of ‘Chandler’ strawberries. Alginate solution (1.5% w/v) and Limonene liposomes prepared from 80% lecithin and 20% PDA were used as edible coating materials. Fungal decay percentage, total yeast and mold counts, headspace atmosphere analysis, total soluble solids, pH, titratable acidity, total anthocyanin content and total phenolics were analyzed to assess fruit quality during 14 days at 4 °C of storage. Days of storage was found to be significant in maintaining the quality of the strawberries. Among the coating types, limonene liposomes were found to be significantly more effective in maintaining the lower concentration of carbon dioxide (CO2), lower the change in pH (3.9), and had higher total anthocyanin (43.85) content during storage than those without a liposomal coating. Thus, limonene liposomes were found to be useful for extending the shelf life and maintaining quality of strawberry fruits

PRETREATMENT OF SWEET SORGHUM BAGASSE TO IMPROVE ENZYMATIC HYDROLYSIS FOR BIOFUEL PRODUCTION

With recent emphasis on development of alternatives to fossil fuels, sincere attempts are being made on finding suitable lignocellulosic feedstocks for biochemical conversion to fuels and chemicals. Sweet Sorghum is among the most widely adaptable cereal grasses, with high drought resistance, and ability to grow on low quality soils with low inputs. It is a C4 crop with high photosynthetic efficiency and biomass yield. Since sweet sorghum has many desirable traits, it has been considered as an attractive feedstock. Large scale sweet sorghum juice extraction results in excessive amounts of waste sweet sorghum bagasse (SSB), which is a promising low cost lignocellusic feed stock. The ability of two pretreatment methods namely conventional oven and microwave oven pretreatment for disrupting lignocellulosic structures of sweet sorghum bagasse with lime [Ca(OH)2] and sodium hydroxide [NaOH] was evaluated. The primary goal of this study was to determine optimal alkali pretreatment conditions to obtain higher biomass conversion (TRS yield) while achieving higher lignin reduction for biofuel production. The prime objective was achieved using central composite design (CCD) and optimization of biomass conversion and lignin removal simultaneously for each alkali separately by response surface method (RSM). Quadratic models were used to define the conditions that separately and simultaneously maximize the response variables. The SSB used in this study was composed of cellulose, hemicellulose, and lignin in the percentage of 36.9 + 1.6, 17.8 + 0.6, and 19.5 + 1.1, respectively. The optimal conditions for lime pretreatment in the conventional oven at 100 °C was 1.7 (% w/v) lime concentration (=0.0024 molL-1), 6.0% (w/v) SSB loading, 2.4 hr pretreatment time with predicted yields of 85.6% total biomass conversion and 35.5% lignin reduction. For NaOH pretreatment, 2% (w/v) alkali (=0.005 molL-1), 6.8% SSB loading and 2.3 hr duration was the optimal level with predicted biomass conversion and lignin reduction of 92.9% and 50.0%, respectively. More intensive pretreatment conditions removed higher amount of hemicelluloses and cellulose. Microwave based pretreatments were carried out in a CEM laboratory microwave oven (MARS 6-Xpress Microwave Reactions System, CEM Corporation, Matthews, NC) and with varying alkali concentration(0.3 - 3.7 % w/v) at varying temperatures (106.4 - 173.6 °C), and length of time (6.6 - 23.4 min). The NaOH pretreatment was optimized at 1.8 (% w/v) NaOH, 143 °C, 14 min time with predicted yields of 85.8% total biomass conversion and 78.7% lignin reduction. For lime pretreatment, 3.1% (w/v) lime, 138 °C and 17.5 min duration was the optimal level with predicted biomass conversion and lignin reduction of 79.9% and 61.1%, respectively. Results from this study were further supported by FTIR spectral interpretation and SEM images

Hydraulic calibration of canal reaches and structures through simulation.

Hydraulic calibration of canals is a prerequisite in effective canal management and an important activity in improving the performance of an irrigation system. Most of the canals and structures in “Track 4” settlement scheme in Ippologama AGA division (D15 canal, D7 canal and its field canals) are not calibrated even after the recent rehabilitation. Water is supplied without any measurements in this area which is selected for the study. Canal Management Software (CanalMan) has wide range of benefits in such situations. However, its applicability in Sri Lanka is still not tested. Therefore, the objectives of this study were to determine the roughness coefficient of different canal reaches and to determine calibration parameters for different inline and off take / turnout structures. The field measurements done for canal simulations included physical parameters of canal reaches and structures, upstream and downstream heads of water in canal reaches and corresponding discharges. Roughness values were calculated with a gradually varied flow profile that matches with given upstream and downstream depths. Calibration parameters, coefficients and exponents were determined from field measurements by representative modeling of flow control structures during a hydraulic simulation. Theoretical considerations and experimental data were combined with engineering judgment to determine appropriate calibration values. CanalMan can be easily and effectively used to determine the hydraulic roughness and calibration parameters within a given or known condition. This allows effective water management by which irrigation diversions can be done efficiently reducing the losses