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Das, Madhusweta
- Measurement of Surface Tension of a Microbial Culture Producing Biosurfactants on N-Alkanes: A Critical Analysis of the Current Methodology
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1 Post Harvest Technology Centre, Indian Institute of Technology, Kharagpur - 721 302, IN
1 Post Harvest Technology Centre, Indian Institute of Technology, Kharagpur - 721 302, IN
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Journal of Surface Science and Technology, Vol 9, No 1-4 (1993), Pagination: 47-55Abstract
The present work reveals, on theoretical basis, that results from measurments of boundary tension of the n-alkane whole broth per se are likely to be inconclusive as to wheather the produced surfactant is extracellular or is cell-associated. Using an isolated Micrococcus species, this study critically examined the influence of the upper floating layer of whole broth on the surface tension arising from the extracellularly produced water soluble biosurfactant. It has also been seen that the observed change in surface tension of the whole broth following serial dilution is not due to the dilution of the produced surfactants in the true sense. Rather, it is due to the progressive removal of the interfering upper layer in parts during the process of serial dilution. Moreover, the extent of dilution of whole broth required to arrive at the CMC (as followed by others) was found to be influenced largely by the quantum of biomass rather than the lipid present in the floating layer.Keywords
Biosurfactants, n-Alkane Fermentation, Surface Tension Measurement.
- Effect of Anti-Caking Agents on Moisture Sorption Isotherms of Palmyra-Palm Jaggery Granules
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Authors
Affiliations
1 All India Co-Ordinated Research Project on Post-Harvest Technology, Regional Agricultural Research Station, Anakapalli (A.P.), IN
2 Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur (W.B.), IN
1 All India Co-Ordinated Research Project on Post-Harvest Technology, Regional Agricultural Research Station, Anakapalli (A.P.), IN
2 Department of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur (W.B.), IN
Source
International Journal of Processing and Post harvest Technology, Vol 8, No 2 (2017), Pagination: 113-122Abstract
Jaggery granules, prepared from palmyra-palm syrup, were mixed with five levels (0.5 to 2 %w/w) of anti-caking agents [tri calcium phosphate, (TCP) or corn starch (CS)] and their moisture sorption isotherms were determined without or with addition of anticaking agents by the static equilibrium method using saturated salt solutions at four temperatures of 25, 35 and 45°C. The moisture sorption isotherms for this granular jaggery samples are Type-III isotherms and the effect of temperature on equilibrium moisture content (EMC) values upto a water activity values of 0.3 to 0.5 show no significant effect. Among two moisture sorption isotherms (MSI) models tested with the experimental data for this high sugar food, GAB model was found to be the best fit followed by Iglesias and Chirife model. The monolayer moisture content (M0) of the granular jaggery samples varied from a minimum of 4.195% (d.b.) for the granulated jaggery without anticaking agent at 45°C to a maximum of 7.303% (d.b.) for granulated jaggery with TCP and 9.178% (d.b.) for granulated jaggery with corn starch @ 2.0% at a temperature of 25°C. A decreasing trend for both Mo and C values but increasing trend for K was obtained with the increase in temperature. The monolayer moisture content of jaggery granules with addition of TCP or CS has been found to posses good correlation with temperature. The net isosteric heat of sorption (qst) of jaggery granules without addition of anti-caking agents, decreased exponentially from 29.132 to 4.833 kJ mol-1 with the increase in moisture content from 2.5 to 15% (d.b.). It was also observed that, net isosteric heat of sorption was found to be higher for the jaggery granules without addition of anti-caking agents as compared to samples with addition of anti-caking agents.Keywords
Jaggery, Palmyra-Palm, Palm Juice, Anti-Caking Agents, Moisture Sorption Isotherm, Water Activity, Net Isosteric Heat of Sorption.References
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