Metabolomics using Gas chromatography-mass spectrometry and antibacterial activity of nine Ocimum taxa of Dakshin Dinajpur district, West Bengal, India

Ocimum traditionally known as Holy Basil or Tulsi is an available herb plenty across the country. Traditionally, it is used against a number of human diseases. In this present study, the metabolites present in the ethanolic extracts of nine Ocimum taxa, O. tenuiflorum L. (Green and purple type) two morphotypes  of O. basilicum L., (Babu and Marua tulsi) two morphotypes  of O. gratissimum L. (Ram and Ajowan tulsi) and each one  from O. americanum L. (Bon tulsi), O. × africanum Lour. (Lebu tulsi), and O. kilimandscharicum Guerke.grown naturally in Dakshin Dinajpur district, West Bengal, India were identified using Gas chromatography–mass spectrometry  (GC-MS). Among the identified metabolites, carbohydrates, aliphatic alcohols, aliphatic acids, fused ring aromatic hydrocarbon, amino acids, phenolic compounds, quinone, steroids, terpenoids and vitamin E were the chief constituents. The occurrence of these metabolites describes the high biological activity of Ocimum species. Furthermore, in vitro antibacterial activities were also identified against four bacterial strains, Staphylococcus aureus (MTCC 96), Bacillus cereus (MTCC 1305), Proteus vulgaris (MTCC 1771) and Escherichia coli (MTCC 2939). Tested bacterial strains were taken from the Institute of Microbial Technology, Chandigarh, India The results indicated that the ethanolic extracts of all the nine Ocimum taxa have satisfactory minimum inhibitory concentration (MIC) values against the tested microorganisms. O. tenuiflorum has the highest (91.03 %) metabolic content whereas O. × africanum has the minimum. This would definitely serve as a scientific basis of the traditional use of basil against human ailments.

Analysis on effect of shapes for microwave-assisted food processing of 2D samples

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Present work provides guidelines on forecasting heating patterns in microwave processed foods which influence their final properties and quality. Three different cross-sections with equal area have been considered, namely, circular, square (indicated as Type1) and square inclined at an angle of 45° with horizontal plane (indicated as Type 2). Have been assumed to be exposed to lateral and radially incident microwaves. Microwave power absorption within samples have been studied using dimensionless parameters, viz. (i) Nw: represents the effect of sample size on power absorption. (ii) fp and fw: represents the effect of dielectric properties on power absorption Food materials were classified into 4 Groups with their fp, fw, as low fp and low fw (Group 1), low fp and high fw (Group 2), high fp and low fw (Group 3), high fp and high fw (Group 4), where low fp (fw) represents fp (fw)<0.3, while high fp (fw) represents fp (fw)_0.3. Power and temperature profiles have been studied in representative materials from each Group. It is found that power absorption profiles for all groups of food and for all the shapes of circular, Type 1 and Type 2 occur in three regime in increasing order of sample size, i.e (i) thin regime: characterized by uniform power absorption (ii) intermediate regime: resonances in absorbed power and (iii) thick regime: exponential attenuation of power within sample. It is also found that, in general identical areas of all the three shapes give rise to identical power absorption at any given sample dimension. Formation and location of hot-spots within material is found to be dependent on the type of incidence, sample dimensions and cross-section of material.dc201

Analysis of microwave thawing of slabs with effective heat capacity method

Microwave thawing of materials, which melt over a finite temperature range, are analyzed using the effective heat capacity method. The state of the material, solid, liquid or mush is deduced from the equilibrium liquid volume fraction vs. temperature relationship for the substance, and the microwave power is calculated from Maxwell's equations. Using Galerkin finite elements, the microwave power, temperature and liquid volume fractions were obtained for microwave thawing of tylose slabs. Thawing progresses from the inside and/or outside depending on the slab thickness. For slabs 5 cm, thawing progresses predominantly from the surface of the sample. Resonances, during which the microwave power absorption is high, causes the 2-cm slab to thaw quicker than 1-cm slabs. A power law for the thawing time vs. sample thickness yields an exponent of 1.56 for microwave thawing and 2 for conventional thawing. To control the temperature rise in the liquid regions, simulations were carried out with an on-off control on the microwave power. On-off control results in greater power savings for thick samples

Role of length scales on microwave thawing dynamics in 2D cylinders

Microwave (MW) thawing of 2D frozen cylinders exposed to uniform plane waves from one face, is modeled using the effective heat capacity formulation with the MW power obtained from the electric field equations. Computations are illustrated for tylose (23% methyl cellulose gel) which melts over a range of temperatures giving rise to a mushy zone. Within the mushy region the dielectric properties are functions of the liquid volume fraction. The resulting coupled, time dependent non-linear equations are solved using the Galerkin finite element method with a fixed mesh. Our method efficiently captures the multiple connected thawed domains that arise due to the penetration of MWs in the sample. For a cylinder of diameter D, the two length scales that control the thawing dynamics are D/D-p and D/lambda(m), where D-p and lambda(m) are the penetration depth and wavelength of radiation in the sample respectively. For D/D-p, D/lambda(m) much less than 1 power absorption is uniform and thawing occurs almost simultaneously across the sample (Regime I). For D/D-p much greater than 1 thawing is seen to occur from the incident face, since the power decays exponentially into the sample (Regime III). At intermediate values, 0.2 < D/D-p, D/lambda(m) < 2.0 (Regime II) thawing occurs from the unexposed face at smaller diameters, from both faces at intermediate diameters and from the exposed and central regions at larger diameters. Average power absorption during thawing indicates a monotonic rise in Regime I and a monotonic decrease in Regime III. Local maxima in the average power observed for samples in Regime II are due to internal resonances within the sample. Thawing time increases monotonically with sample diameter and temperature gradients in the sample generally increase from Regime I to Regime III. (C) 2002 Elsevier Science Ltd. All rights reserved

Influence of Internal Convection during Microwave Thawing of Cylinders

Numerical simulations were carried out for microwave thawing of 2-D cylinders of pure materials with internal convection in the liquid regions. Enthalpy formulation of the energy balance equation was used with a superficial mushy region around the melting point. Electric field, energy and momentum balance equations were solved using the Galerkin finite-element method with the penalty finite element formulation of the momentum balance equation. Microwave power absorption, temperature, and stream functions were studied for various cases. For samples of diameter D, thawing was contrasted between samples for $0.032<D/D_p<3.73$ and $0.10<D/\lambda_m<1.58$. These ratios were $D_p$ computed based on the liquid-phase penetration depth D and wavelength of microwave radiation in the medium $\lambda_m$. In all cases, Pr=0.5 was used and the Rayleigh m number varied from $1.067\times10^3$ for the smallest diameter to $1.33416\times10^5$ for the largest sample (D=2 cm) . Thawing was contrasted for MWs being incident from the top and bottom faces of the cylinder and with the thawing dynamics in the absence of convection in the liquid. Our simulations indicate that convection plays a small role for $D/D_p \ll 1$ and thawing is independent of the direction of MWs. At intermediate values p of $D/D_p$ where a strong maximum occurs in the power, the influence of convection with p primary and secondary cell formation in the liquid regions was a strong function of the direction of incident microwaves. In the presence of multiple connected thawed regions convection was suppressed