Masitah Hasan

Kinetics of the enzymatic hydrolysis of palm oil by lipase

Abstract The kinetics of the enzymic hydrolysis of palm oil using lipase in a batch reactor has been investigated. The lipase enzyme used was not ester bond position selective and its activity at the interface was higher compared to that in the bulk. A mathematical model taking into account the mechanism of the hydrolysis reaction and the effect of interfacial area between the oil phase and the aqueous phase containing the enzyme was developed. A correlation between the interfacial area and the operating conditions including agitation speed and oil volume fraction was established experimentally. The kinetic parameters were estimated by fitting the data to the model and comparing with previously reported values. The kinetic model represented the experimental data accurately.

Effect of operating variables on the hydrolysis rate of palm oil by lipase

Hydrolysis of palm oil by lipase enzyme in aqueous phase was studied in a well stirred bioreactor under defined mixing conditions. Agitation speed, concentration of the surfactant, palm oil, and the enzyme were varied to study their effect on the initial rate of hydrolysis. Addition of surfactant, gum arabic, increased the rate of hydrolysis and its optimum amount was found to be 25 mg l−1. The optimum enzyme loading was found to be 92.5 kLU l−1. Studies on the effect of agitation speed and substrate concentration showed that the initial rate of hydrolysis is dependent on the interfacial area between the oil phase and the aqueous phase containing the enzyme. No substrate inhibition was observed in the range of palm oil concentration 0–262 g l−1, used in this study.

Supercritical CO2 fractionation of crude palm oil

Abstract Crude palm oil was fractionated using supercritical CO 2 (SC–CO 2 ) in a semi batch apparatus. The fractionation conditions studied were at 40, 50 and 60°C and at 110, 140 and 200 bars, respectively. System pressure was found to be more significant rather than temperature for increasing the solubility of palm oil triglycerides in SC–CO 2 . The solubility of crude palm in SC–CO 2 was generally low for triglycerides rich in the saturated and lower molecular weight fatty acids, i.e. C12:0, C14:0 and C16:0. These fatty acids were fractionated first followed by the heavier and mainly unsaturated fatty acids, i.e. C18:1, C18:3 and C20:0. The initial extracted fractions were white to yellow in colour and solid like. The later fractions however were more intense in colour and semi-liquid. It was difficult to extract β-carotene from the palm oil in the fractions even at high pressures because it is concentrated in the raffinate. The del Valle-Aguilera correlation was found to over estimated solubility of crude palm oil in supercritical CO 2 .

Supercritical Carbon Dioxide Extraction of Andrographolide from Andrographis paniculata: Effect of the Solvent Flow Rate, Pressure, and Temperature*

Abstract Andrographis paniculata Nees has been extensively used for traditional medicine and help against fever, dysentery, diarrhoea, inflammation, and sore throat. In this study, andrographolide, the main component of this plant was extracted from the leaves of A. paniculata using supercritical carbon dioxide. The operating pressures were varied from 7.50 to 20MPa, the temperatures were varied from 30°C to 60°C, and the flow rates were varied from 0.5 to 4ml·min-1. The best extraction condition occurred at 10MPa, 40°C, and a flow rate of 2ml·min-1 for a 3g sample of A. paniculata ground-dried leaves. The measured extraction rate was found to be about 0.0174g of andrographolide per gram of andrographolide present in the leaves per hour of operation. The future studies must focus on the interaction between the various operating parameters such as temperature, pressure, and flow rate of supercritical carbon dioxide.

Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria.

Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO(2) and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO(2), (II) bicarbonate plus continuous sparging of CO(2), and (III) only bicarbonate. The pH-reducing nature of CO(2) showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO(3)(-)-N/g MLVSS/h for degrading 20 and 30 mg NO(3)(-)-N/L and 9.09 mg NO(3)(-)-N/g MLVSS/h for degrading 50mg NO(3)(-)-N/L.

A kinetic study of autohydrogenotrophic denitrification at the optimum pH and sodium bicarbonate dose

In this study the kinetics of autohydrogenotrophic denitrification was studied under optimum solution pH and bicarbonate concentration. The optimal pH and bicarbonate concentration were firstly obtained using a design of experiment (DOE) methodology. For this purpose a total of 11 experiments were carried out. Sodium bicarbonate concentrations ranging of 20-2000 mg/L and pH values from 6.5 to 8.5 were used in the optimization runs. It was found that the pH has a more pronounced effect on the denitrification process as compared to the bicarbonate dose. The developed quadratic model predicted the optimum conditions at pH 8 and 1100 mg NaHCO(3)/L. Using these optimal conditions, the kinetics of denitrification for nitrate and nitrite degradation were investigated in separate experiments. Both processes were found to follow a zero order kinetic model. The ultimate specific degradation rates for nitrate and nitrite remediation were 29.60 mg NO(3)(-)-N/g MLVSS/L and 34.85 mg NO(3)(-)-N/g MLVSS/L respectively, when hydrogen was supplied every 0.5h.

Solubility of Piperine in Supercritical and Near Critical Carbon Dioxide

Abstract Piperine is a member of the lipids family commonly found in peppercorn, ginger and other natural sources and is grouped as an alkaloid. The solubility of piperine has been determined in carbon dioxide at near critical and supercritical conditions in a dynamic extraction apparatus. The conditions studied were at pressures ranging from 10 to 20 MPa and temperatures at 293, 300, 313, 323 and 333 K. The results showed that piperine solubility increased with increasing pressure at all temperatures studied. The solubility of piperine in near critical conditions was slightly higher than that at supercritical conditions only at the low-pressure range. Two semi-empirical density dependent correlations, namely the Chrastil model and the Dilute Solution model, were also used to estimate the solubility data. Although both models showed good correlation with the solubility data, the Dilute Solution model performed better prediction than the Chrastil model.

Chemical Profiling and Quantification of Tannins in Phyllanthus niruri Linn. Fractionated by SFE Method

Chemical profiles or fingerprints of polyphenolic compounds (condensed and hydrolyzable tannins) in various fractions of Phyllanthus niruri Linn extracted using supercritical carbon dioxide and various polar cosolvents, namely water, methanol, and ethanol are presented. Chemical analysis of the extracted fractions was undertaken using High Performance Liquid Chromatography (HPLC) with the in-house method. Good peak reproducibility of intra-day (R.S.D range 0.01–0.21 min) and inter-day (R.S.D range 0.5–0.8 min) was obtained for the detection of ellagitannins (hydrolyzable tannins) and flavonoids (condensed tannins). Fractions extracted using ethanol-water mixtures as cosolvent at 200 bar and 60°C exhibited an appealing behavior whereby non-polar compounds and flavonoids were able to be fractionated before the extraction of ellagitannins. Contents of three major ellagitannins, namely gallic acid (0.39–0.48% g/g), corilagin (2.42–3.00% g/g), and ellagic acid (5.94–6.48% g/g), were relatively higher compared to the commercial HEPAR-P™ standardized extract (0.21, 2.64, and 4.17% g/g, respectively). The study shows that the supercritical fluid extraction (SFE) method with the use of appropriate cosolvents is able to produce P. niruri fractions with improved yields and different chemical characteristic, which thus can be used as a rapid preparative tool for further downstream processing of plant samples.

Pressurized water extraction of hydrolysable tannins from phyllanthus niruri linn

Pressurized water extraction (PWE) was studied for the extraction of hydrolysable tannins from Phyllanthus niruri Linn. The effects of operating conditions (pressure, temperature, and the water flow rate) on the extraction yields were investigated. The results showed that the extraction yields increased with increasing temperature and with decreasing water flow rate, whereas pressure gave no significant effect. At 100 bar, 100°C and 1.5 ml/min, the extract had higher component contents (%g/g extract) of gallic acid (0.65%), corilagin (4.11%), and ellagic acid (8.91%) than a commercial HEPAR-P™ extract (0.21%, 2.64%, 4.17%, respectively). It was also found that the dynamic PWE had a faster extraction rate and lower solvent consumption (0.018 m3/kg) compared to the Soxhlet extraction and ultrasonication.