Physico-Chemical Characterization and Microbial Studies of Muscle Lipid of Liner Silver Grunter (Pomadasys hasta) of the Bay of Bengal

Lipid was extracted from the lipid containing muscle of Liner silver grunter (Pomadasys hasta) by solvent extraction and then purified by standard method. The physico-chemical properties of lipid sample were determined and compared with those of other standard fats and oils. Fatty acid composition of the lipid sample was investigated by Thin Layer Chromatographic (TLC) examination. Gas Liquid Chromatographic (GLC) examination was performed by the methyl esters mixture prepared from the lipid sample. The de-oiled muscle of the fish was studied for the determination of ash content, fiber content, moisture content and protein content. The lipid containing selected muscle was analyzed quantitatively for the determination of percentages of protein, cholesterol and minerals (N, P, K, Ca, and Na). The lipid containing muscle was also analyzed for the determination of the amount of eleven metals by using Atomic Absorption Spectrophotometric method. The lipid sample was evaluated by microbial activity (bacterial activity against nine bacteria and fungal activity against seven fungi).

Multiplex microfluidic system integrating sequential operations of microalgal lipid production

We developed a PDMS-based multiplex microfluidic system with eight chambers and micropillar arrays to expedite multiple steps for lipid sample preparation from different microalgal strains.

Light-induced TPP photoproduct formation in chloroform and protective role of lipids

In this contribution, the influence of lipids on excitation energy transfer from lipophilic photosensitizer tetraphenylporphyrin to oxygen was investigated in chloroform solutions of phosphatidylcholine as well as in bulk lipid. The excited states kinetics were examined in a wide range of lipid concentrations (from zero to the saturated concentration) by direct time- and spectral-resolved detection of weak near infrared phosphorescence of the photosensitizer (around 840 nm) and singlet oxygen (about 1278 nm). While photosensitizer triplet kinetics follows single-exponential decay with lifetime of 0.52 μs in pure chloroform, two distinct components with lifetimes of approximately 0.4 and 1 μs appear after phosphatidylcholine addition. Both the lifetimes exhibit shortening tendency with increasing lipid concentration. Relative weights of the two components depend on the lipid concentration. Singlet oxygen kinetics exhibit single-exponential rise with lifetimes roughly corresponding to the shorter components of photosensitizer decays while their decays require two exponentials. The lifetime of the longer component decreases with increasing concentration of lipid from (77.6 ± 1.3) μ s at pure chloroform to (14.3 ± 1.1) μ s at the saturated lipid concentration. The time-constants obtained in bulk lipid sample follow the above-mentioned trends. Tetraphenylporphyrin photoproduct formation under pulsed excitation in chloroform solutions was demonstrated. The quantum yield of singlet oxygen production of the photoproduct is lower than that of the tetraphenylporphyrin. It was shown that lipids prevent the singlet-oxygen mediated formation of TPP photoproduct, probably by efficient quenching of singlet oxygen. This quenching is justified by shortening of the longer component of singlet oxygen luminescence decays with increasing concentration of the lipid. Moreover, the lipids also quench triplet states of the photosensitizer.

Liquid Chromatographic Method for Determining the Percent of Olestra in Lipid Samples

A liquid chromatographic (LC) method has been developed to determine the percent of olestra in lipid samples. To achieve the highest degree of accuracy, this method requires the use of an olestra standard with the same molecular composition as the olestra in the lipid sample to be analyzed. Samples were analyzed by reversed-phase LC using an evaporative light-scattering detector. Chromatography was performed with a 5 μm octadecylsilane- Zorbax column that separates olestra from other lipophilic components. Three types of olestra standards (soybean-oil olestra, unheated cottonseed- oil olestra, and heated cottonseed-oil olestra), each analyzed in soybean oil, showed linearity when the amount of olestra injected ranged from 20 to 160 fig (r= 0.9996). The area under the olestra peak (retention time 3.5 to 4.9 min) was used to quantify the amount of olestra in olestra-lipid samples, by comparing the olestra area for the sample with that of the standard using a curve derived by linear regression. The method was evaluated using 3 types of olestra blended with soybean oil and varying the percent of olestra in the olestra-lipid blend from 5 to 90%. Recovery of olestra from these olestra-lipid blends varied from 99.2 to 106.0%, demonstrating excellent accuracy, with method precision expressed as the coefficient of variation, 0.9%. Each error estimate was derived from 5 parallel determinations. With proper validation (e.g., running an olestra-free blank for each lipid matrix), this method provides a rapid, accurate, and precise technique for measuring the percent of olestra in lipids extracted from olestra-formulated foods and in olestra-lipid blends.

Evaluation of Signal Reabsorption and Sample Heating in NIR-Raman Measurements

In order to assess the magnitude of the experimental problem of NIR absorption in NIR-Raman measurements, 1064 nm-Raman spectra of representative scattering lipid suspensions were measured, the spectral artifacts were compared, and the relative magnitude of sample heating was determined by using principal component analysis to measure the shift in a thermotropic phase transition. As in a previous evaluation of the problem, solvent O-H absorption was found to be the main difficulty because it significantly attenuates the Raman signal from C-H stretching. This is true even though the effective sample thickness was only 175 μm. Small Raman intensity artifacts were created by the changes in NIR absorption or optical scattering that occur with changing lipid concentration or state of liposome aggregation. Though use of D2O as the suspending solvent greatly improved the intensity of the C-H stretching region, in comparison to H2O suspensions, observed laser heating was reduced by only a factor of two. C-H stretching absorption can contribute to the heating when D2O is the solvent. In D2O the lipid sample heating was reduced to an acceptable level (1°C) when the laser illumination was 740 mW over a 2.5-mm circular spot. Thus power density needs to be kept at less than 1/10 that typically used in similar visible Raman experiments. O-H containing samples without strong optical scattering show pronounced spectral attenuation in the 180° geometry, if the spectrometer optics collect from deep within the specimen. This consideration places limitations on the use of long pathlengths to improve signal intensity. Extinction pathlengths available from the literature provide a convenient way to extrapolate these results to other NIR excitation wavelengths. Shifting excitation from 1064 nm to 910 nm would avoid most of the Raman spectral attenuation by O-H and reduce the H2O lipid suspension sample heating by a factor of two. Unfortunately, heating of the D2O suspensions will not be significantly reduced even if the excitation is moved to 830 nm.