K. Udaya Sankar

Characterization of chitin, chitosan and their carboxymethyl derivatives by differential scanning calorimetry

Abstract Chitin, chitosan and their O , N -carboxymethyl derivatives were characterized by differential scanning calorimetry (DSC) mainly focusing on changes in physical and chemical structures at different levels of acetyl and carboxymethyl contents. The thermograms were characterized by endo- and exotherms corresponding to water evaporation and decomposition of the polymer, respectively. However, each endo- or exothermic peak temperature and area changed as a function of primary and higher order structures of the macromolecule. It was found that the enthalpy value for endotherm increased with increase in amino and carboxymethyl contents. Further, in the case of carboxymethyl derivatives, no glass transition was observed despite the presence of substantial amount of amorphous content. During decomposition, the decomposition peak temperature and area changed as a function of molecular weight (MW), acetyl and carboxymethyl contents. A theoretical basis was adopted to correlate the heat of the reaction, Δ H , to the degree of deacetylation (%DD) and carboxymethylation (DS). A good correlation was obtained when the corresponding peak area and peak height were plotted against %DD and DS.

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.

Analysis of Predominant Steviosides in Stevia rebaudiana Bertoni by Liquid Chromatography/ Electrospray Ionization-Mass Spectrometry

Stevia reabudiana is gaining popularity especially in making diabetic food supplements in view of its non-nutritive glycosides. Steviosides profile in ex vitro and in vitro leaves and callus cultures of S. rebaudiana were investigated by HPLC analysis and further confirmed by MS using mass spectral fragmentation data obtained from LC-MS-ESI studies. The leaf samples (4 weeks old) and callus cultures (2 weeks old) were used for extraction and extracts were used for HPLC analysis. Predominantly, eight sweet diterpene glycosides were detected. The highest stevioside content of 6.48% Steviolbioside and 0.099% Rebaudioside-A on a dry weight basis were found in ex vitro and in vitro leaves, respectively. In callus and suspension cultures, the biosynthesis of steviosides was observed except for steviolbioside. The LC-MS-ESI based detection of different steviosides in Stevia cultures could be used for comprehensive qualitative evaluation of the samples.

Changes in the physical-chemical and organoleptic characteristics of parotta during storage

Abstract Studies on the changes in quality of parotta during storage from 0.25 to 48 h indicated a decrease in alkaline water retention capacity (AWRC) from 257.4 to 127.7%, in total water solubles (TWS) from 8.25 to 6.24%, in soluble starch (SS) from 2.11 to 1.19%, in solubilised amylose from 0.39 to 0.13% and in solubilised amylopectin from 1.72 to 1.06%. The pasting characteristics of stored parotta measured using a rapid visco analyser showed a decrease in maximum viscosity at 95°C from 54 to 37 RVU. The overall quality score of parotta based on colour, nature of spots, shape, oiliness, handfeel, texture, layers, mouthfeel, taste and aroma decreased from 75 to 43 while the shear and compression force of parotta increased from 12.3 to 21.6 N and 304 to 711 N respectively, with storage time. The AWRC, SS, amylopectin and viscosity at 95°C showed a highly significant correlation (r⩾0.956, P

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.

Physical behavior of purified and crude wax obtained from Sunflower (Helianthus annuus) seed oil refineries and seed hulls

The sunflower seed waxes obtained from two sources (i) seed hull as a standard and (ii) crude wax from oil refineries were studied for their crystallization, melting characteristics and morphology of crystals. The results of differential scanning calorimetry of wax obtained from seed hulls showed the melting temperature range of 13.18 degrees C with the onset at 62.32 degrees C, for purified wax, compared to the melting range of 24.73 degrees C with the onset at 42.3 degrees C. for crude wax. The enthalpy of fusion for both waxes were 57.55 mcal/mg and 7.63 mcal/mg, respectively. The DSC melt crystallization temperature range was 15.79 degrees C with the onset of 64.58 degrees C for purified wax and temperature range of 31.45 degrees C with an onset of 57.76 degrees C for crude wax. A similar pattern was observed of wax obtained from the crude wax of oil refineries. The enthalpy of crystallization was -64.27 mcal/mg and -7.67 mcal/mg, respectively. The purified wax obtained from the two sources (i) and (ii) were comparable with completion temperatures of 75.5 degrees C and 75.1 degrees C, respectively. The effect of inhibitor (lecithin) on crystallization of purified wax under light microscope and surface structure by scanning electron microscope were observed. Lecithin at 0.2% inhibited the crystallization but nucleation was unaltered. The wax crystal was inhibited to around 60% of the original size with 0.2% lecithin. It is concluded that the sunflower waxes studied were not comparable in their crystal properties of crude and purified states. Lecithin inhibited the crystallization of sunflower seed wax.The sunflower seed waxes obtained from two sources (i) seed hull as astandard and (ii) crude wax from oil refineries were studied for theircrystallization, melting characteristics and morphology of crystals. Theresults of differential scanning calorimetry of wax obtained from seed hullsshowed the melting temperature range of 13.18 °C with the onsetat 62.32 °C, for purified wax, compared to the melting range of24.73 °C with the onset at 42.3 °C, for crude wax. Theenthalpy of fusion for both waxes were 57.55 mcal/mg and 7.63 mcal/mg,respectively. The DSC melt crystallization temperature range was15.79 °C with the onset of 64.58 °C for purified wax andtemperature range of 31.45 °C with an onset of 57.76 °C forcrude wax. A similar pattern was observed of wax obtained from thecrude wax of oil refineries. The enthalpy of crystallization was –64.27mcal/mg and –7.67 mcal/mg, respectively. The purified wax obtained fromthe two sources (i) and (ii) were comparable with completion temperaturesof 75.5 °C and 75.1 °C, respectively. The effect of inhibitor(lecithin) on crystallization of purified wax under light microscope andsurface structure by scanning electron microscope were observed. Lecithinat 0.2% inhibited the crystallization but nucleation was unaltered. Thewax crystal was inhibited to around 60% of the original size with 0.2%lecithin. It is concluded that the sunflower waxes studied were notcomparable in their crystal properties of crude and purified states.Lecithin inhibited the crystallization of sunflower seed wax.

Infrared spectroscopic study of the structural transitions of C60Br24

Abstract Variable temperature infrared spectroscopy and differential scanning calorimetry measurements show that C 60 Br 24 under-goes two structural transitions at 171 and 180 K with ΔH values of 0.87 and 3.94 kJ mol −1 respectively. Only one transition is clearly visible in IR which is manifested by the hardening of certain IR peaks and narrowing of the 1400 cm −1 transition. The results support an orientational change although ordering of the solvated bromine molecules could also be a reason for the observed changes.

Supercritical fluid extraction from dry mouldy bran for the purification of gibberellic acid from the concomitant products produced during solid state fermentation

Abstract Dry mouldy bran (DMB) containing gibberellic acid (GA3) is a solid fermented material resulting from solid state fermentation by Gibberella fujikuroi P-3. Samples of this bran were subjected to supercritical fluid extraction (SCFE) to remove other concomitant products which are produced during the fermentation process. A fungal sterol, identified as the major component in the extract, was found to disturb the defensive mechanism in rice seedlings. The physicochemical and spectral characteristics of this sterol were established. The extraction of the sterol by SCFE was found to improve with the use of an entrainer (ethanol). The fungal mycelia and spores were disintegrated during the SCFE process. The solid material retained the GA3 activity without any loss during extraction and can be used directly for application on agricultural fields.

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.

Response surface methodology applied to fractionation of de-oiled soya lecithin obtained by supercritical carbon dioxide extraction

Soya lecithin, de-oiled by supercritical carbon dioxide extraction at 200 bar and 50°C, was subjected to ethanol extraction for the enrichment of phosphatidylcholines (PC). The process variables time, temperature and ethanol—lecithin ratio were studied for optimization of PC enrichment by response surface methodology following a Box-Behnken design of experiments. An optimum value of PC enrichment was not found. However, the results indicated: (a) PC enrichment generally increased with an increase in all three variables. (b) Until 5 min extraction time, there is no significant increase in PC enrichment. (c) Above an ethanol—lecithin ratio of 50 L/kg, not much increase in PC enrichment was noticed. (d) A rise in the temperature of extraction leads to increase in PC enrichment.