Balaraman Manohar

Optimization of isoamyl acetate production by using immobilized lipase from Mucor miehei by response surface methodology.

Immobilized lipase from Mucor miehei was employed for the esterification of isoamyl alcohol with acetic acid in n-heptane solvent. The important process variables studied were enzyme/substrate (E/S) ratio, alcohol (acid) concentration, and incubation period. Based on Box-Behnken design of experiments, a second order response function was developed. The percentage esterification increased with both E/S ratio and time and decreased with alcohol (acid) concentration. The model indicated optimum conditions for maximum esterification ranging from 20 to 99.6% in the alcohol (acid) concentration range of 0.031 to 0.3 M for a range of E/S ratios 8.33 to 50 g/mol, which were in good agreement with the experimental yields.

Bioactive principles from Cordyceps sinensis: A potent food supplement - A review

Abstract Cordyceps sinensis (CS) is a well-known entamophagus fungus, naturally distributed in the Tibetan Plateau of Asia and Himalayas. Recently this synonym is transferred to Ophiocordyceps by both scientific and non-scientific communities. It is widely used as a tonic and medicinal food in traditional Chinese medicine (TCM), as it possess wonderful health benefits. To support its functional attributes, various investigations have been carried out to find out its adaptogenic, aphrodisiac, anti-oxidant, anti-aging, neuroprotective, nootropic, immunomodulatory, anti-cancer and hepatoprotective role. Its fruiting portion as well as the larvae possesses potent bio-active fractions and their composition almost found to be similar in both. The bioactive principles are nucleosides, exo-polysaccharides, sterols and, proteins, among others. Among nucleosides, adenosine and cordycepin are the major biochemical markers. Further, different types of solvent extracts and their mixtures exhibit wide range of pharmacological activities, while the water and methanol extracts with the richest sources of nucleosides and polysaccharides also show wide range of pharmacological activities. This review gives a panoramic view of potential health benefits of various classes of bio-active fractions along with the need for sustainable management of CS for human wellness.

Applications of surface plots and statistical designs to selected lipase catalysed esterification reactions

Abstract The usefulness of several statistical designs in experimental optimisation including Box-Behnken, Central Composite Rotatable and Plackett–Burman designs in lipase catalysed esterification reactions is presented. Analyses of several response surface plots obtained by employing statistical designs in lipase catalysed esterification reactions have indicated that such plots could be grouped into four types to explain esterification behaviour in the presence of different kinds of substrates and reaction conditions. Similarly, a Plackett–Burman design helps in the selection of the most probable organic acid or alcohol in a mixture, for a facile esterification reaction. Predominant acid binding in preference to alcohol gives rise to dome-shaped response surface plots. Predominant alcohol binding in preference to acid give rise to inverted dome-shaped plots. The competitive and inhibitory nature of substrates are brought out clearly in response surface plots. Rate plots show linear relationships between time and substrate with smooth surfaces within the limits of the variables employed. There are other uneven plots, which reflect the effect of variables like buffer pH, buffer volume and temperature on the activity of lipase employed. The stability of lipases under drastic esterification conditions of temperature and solvents was also studied.

A central composite rotatable design analysis of lipase catalyzed synthesis of lauroyl lactic acid at bench-scale level

Abstract Porcine Pancreas lipase (PPL) was employed for the reaction between lactic acid and lauric acid at bench-scale level. A Response Surface Methodological (RSM) study was conducted by employing a five-level, five variable, central composite rotatable design (CCRD) in order to understand the esterification behavior of PPL in the lauroyl lactic acid synthesis. Five important variables were considered, namely, enzyme/substrate (E/S) ratio (0.09–1.14 Activity Units/mmole - AU/mmol), lactic acid concentration (5–25 mmol), incubation period (6–54 h), buffer volume (0–0.2 ml) and buffer pH Values (4.0–8.0). Highest ester yield of 6.8 mmol was predicted at the lowest E/S ratio of 0.09 AU/mmol. Lower E/S ratios gave higher yields and higher E/S ratios gave lesser yields. This behavior clearly explained the competitive nature of binding between lauric and lactic acids for the same binding site on the enzyme. Addition of buffer in terms of both volume and pH did not have a profound effect on increase in ester yield. Predicted yields showed good validation with experimental yields when experiments corresponding to selected points on the contour plots were carried out.

Some physical properties of tamarind (Tamarindus indica L.) juice concentrates.

Abstract Flow properties of tamarind (Tamarindus indica L.) juice concentrate were studied over a concentration range of 7–62 °Brix and a temperature range of 298–343 K using a coaxial cylindrical viscometer. The concentrates showed Newtonian flow behaviour up to a concentration of 19 °Brix and pseudoplastic nature beyond 23 °Brix obeying the power law relationship. Flow behaviour index for concentrate of 23 °Brix is 0.747, whereas it is 0·625 for concentrates of 28–62 °Brix. Tamarind juice concentrates were more viscous than sucrose solutions especially at higher concentrations. Whereas the activation energy of sucrose solutions varies with concentration, it does not vary with concentration in the case of tamarind concentrates. Some other engineering properties such as boiling point elevation, specific heat and specific gravity of tamarind juice and concentrates were determined. The effects of concentration and operating variables on these properties were studied and mathematical models were proposed to relate them to the properties. The boiling point elevation of tamarind juice is twice that of sucrose solutions at 50% solid content and 150 mm Hg absolute pressure. However, the difference is less at lower concentrations (below 20% solid content). The specific heat of tamarind juice is less than that of sucrose solutions at all concentrations. The specific gravity of tamarind juice is approximately equal to that of sucrose solutions of the same concentration.

Rheology and particle size changes during Idli fermentation

Changes in rheological properties and particle size during fermentation of idli (a fermented food made from rice and black gram) were investigated; dimensional parameters of batter formed using a specially developed automated idli processing unit and the effects of rice:black gram ratio (2:1, 3:1 and 4:1) on idli quality were also studied. Shear stress and shear rate values obtained for different idli batters during fermentation (23 h at ambient temp.) showed good agreement with the power law model with yield stress. Yield stress values were in the range 13-43 Pa and reached a max. value at 7 h of fermentation. Flow behaviour indices were in the range 0.287-0.605, indicating strong non-Newtonian behaviour. Consistency index was observed to increase with increasing rice:black gram ratio at all fermentation times. Particle sizes in batters ranged up to 2000 mum; approx. 80% of particles were <782 mum and mean particle size for all batter types as a function of fermentation time ranged from 500 to 600 mum. No defined trend in particle size with respect to fermentation time and rice:black gram ratio was observed; however, a small increase in mean particle size occured between 4 and 13 h of fermentation. Height of batters showed little variation between batter types while diam. decreased with increasing ratio rice:black gram ratio. A rapid vol. increase was observed in batters after 4 h fermentation; rate of vol. increase progressed steadily until approx. 13 h and then slowed down.

Application of central composite rotatable design to lipase catalysed synthesis of m-cresyl acetate

Esterification of m-cresol with acetic acid using porcine pancreas lipase (PPL) was investigated by response surface methodology (RSM). A central composite rotatable design (CCRD) involving 32 experiments of five variables at five levels was employed to analyse the esterification behaviour. The effect of five variables studied namely, m-cresol concentrations (0.005–0.025 mol), enzyme/substrate ratios (0.18–1.22 activity units/millimol, AU/mmol), incubation periods (6–54 h), pH (4–8) and buffer volumes (0–0.2 ml) was useful in arriving at an optimum ester yield. The methodology projected conditions for higher yields up to 6.0 mmol. Validation experiments carried out under these predicated conditions showed good correspondence between experimental and predicted yields. CCRD treatment clearly showed the inhibitory nature of m-cresol in the esterification process. The reaction required the presence of buffer for better conversions and a minimum amount of 0.1 ml buffer was found necessary for this reaction. Buffer pH values around 6.0 and below appeared to favour better esterification than those at pH values in the range 6.0–8.0. However an optimum condition for maximum yield was: incubation period: 54 h; buffer volume: 0.2 ml; pH: 8; E/S ratio: 0.83 AU/mmol; m-cresol: 0.02 mol; predicted yield: 6.0 mmol; experimental yield: 6.4 mmol.

Response surfaces for solubility of crude soylecithin lipid in super critical carbon dioxide

Abstract The solubility of soy lecithin lipids in supercritical CO2 was measured at pressures of 120, 200 and 280 bar and at temperatures of 40, 50 and 60  °C. The effects of temperature and pressure on the solubility of total lipids were studied by response surface methodology. The response surface equation to predict the solubility of total lipids in the above range of pressure and temperature is: Y=–3.237+0.0431* P–7.3×10–5P2–0.00011 P*T where Y is the total lipid solubility in g/kg CO2, P is the pressure in bar and T is the temperature in   °C. The total lipids solubility increased with pressure at constant temperature, but decreased with increasing temperature. The total lipids consisted of a very small phospholipid content compared to neutral lipids and glycolipids at all the pressures and temperatures studied. Optimum search indicated a maximum solubility of total lipids of 1.829 g/kg CO2 at 263 bar and 40  °C.

Grinding of Coriander Seeds: Modeling of Particle Size Distribution and Energy Studies

Coriander seeds were ground in an impact type hammer mill and a pin mill to study the pattern of particle size distribution and their relationship with energy consumption. The particle size distribution for all samples was best described by the Rosin-Rammler-Bennett (RRB) and model with high degree of correlation coefficient compared to the Gaudin-Shumann (GS) model and Log-normal function. Particle size distribution was also characterized by various size parameters such as: uniformity index, size range variation coefficient, mass relative span, skewness, kurtosis, size guide number, coefficient of uniformity, and the coefficient of gradation and geometric standard deviation. Energy consumption for grinding was studied based on classical grinding laws, namely, Bonds, Rittengers and Kicks law. Bonds Work index varied from 0.5 to 4.3 kJ kg−1 depending on the size reduction ratio. Energy consumption followed a linear relationship with size reduction ratio.

Prediction of solubility of Psoralea corylifolia L. Seed extract in supercritical carbon dioxide by equation of state models

Solubility of bakuchiol and psoralen, key components of Psoralea corylifolia L. seed extract, in supercritical carbon dioxide was predicted by employing well known Peng-Robinson and Soave-modified Redlich-Kwong equations of state. Solubility (in mole fraction) of both bakuchiol and psoralen was in the range 10−6–10−4 for the pressure 22 to 30 MPa. Both the models were found to agree with the experimental solubilities of psoralen very well with average deviation less than 9%. If the extract was assumed as a single pseudo-component having average critical properties of main components, the model predicted solubility of the extract well with average deviation less than 17%. Critical properties necessary for the solubility prediction such as critical temperature, critical pressure, and critical volume were predicted for the key components following group contribution methods proposed by Ambrose, Lydersen, Joback and Klincewicz-Reid. Vapor pressure of the components was also predicted based on Riedel equation. Depending on the temperature, vapor pressure of Psoralen is higher by a factor of 10 to 2 × 1011 compared to vapor pressure of bakuchiol.