Shrilekha Das

Polyphenoloxidase and peroxidase activity and moisture loss have been used for optimization of withering parameters in black tea production. Leaves of TV25 clone were withered at different air temperature (25, 30, 35 °C) and relative humidity (RH) (60, 75, 85%), with constant air flow rate. With higher air temperature, polyphenoloxidase specific ac...

Analysis of four different catechins, four theaflavins (TF), and thearubigin (TR) in oxidizing macerated CTC (crush–tear–curl) and rolled orthodox leaves of TV25 clone was done. Tea leaves were oxidized at different air temperatures (20, 25, 30, and 35°C) and thickness of oxidizing leaf bed (2 and 5 cm). Rate of depletion of catechins was modeled u...

Drying is a complex phenomenon and study of drying kinetics and modelling is very important for describing the moisture movement with respect to time and predicting the dryer performance. Considering this fact, vacuum drying characteristics of cherry pepper was studied at different drying temperatures (50, 60 and 70oC). Cherry pepper were dried fro...

Oxidation of withered and macerated crush‐tear‐curl (CTC) and rolled orthodox tea leaves of TV25 clone was carried out in a closed chamber and oxygen and carbon dioxide concentration inside the chamber was measured at small time intervals. From the O2 consumption and CO2 production pattern during oxidation, mass transfer coefficient (ky′) and mass...

In black tea manufacturing, one of the most important steps is fermentation which influences the quality of tea. The macerated tea leaves were fermented at various temperatures (20, 25, 30, 35 °C) for different duration. Changes in polyphenoloxidase and peroxidase activities, depletion patterns of individual catechins, differences in individual the...

A method of sensory evaluation using fuzzy logic has been proposed in this paper. The method was applied for evaluation of sensory quality of tea liquor made out of dried CTC tea. Linguistic data (e.g., excellent, very good, good, satisfactory, fair, not-satisfactory, etc.) on individual tea liquor’s quality attributes and the perception of the eva...

Orthodox and CTC tea were dried in hot air, radio frequency and hybrid hot air – radio frequency (RF) dryers for comparisons of drying durations and quality parameters. Drying duration was the shortest for RF drying at 60 min for orthodox tea where as for CTC tea it was 90 min. Hybrid drying for CTC tea took total of 55 min and the same for orthodo...

Withering process involves changes in physical and chemical character of the tea leaf. The total withering time may vary from 12 to 14 h depending on the type of leaf and moisture content. Of the total energy consumption in tea processing withering requires considerable amount of electrical power to complete the process. Oflate researchers are enga...

Chhana, a heat-acid coagulated product of milk, is pressed to make paneer. Like Tofu, paneer is extensively used for the preparation of a large number of culinary dishes. For the pressing, chhana was kept in cages made from a special type of screen and the cages were subjected to impact forces. Total amount of energy imparted to chhana during impac...

Results of 57Fe Mossbauer investigation in a layered cyanide Mg(Mg((CH2)6N4)2Fe(CN)6)2.nH2O for different stages of hydration are presented. Mossbauer spectra in the partially hydrated stages show an asymmetry in the intensity of the two absorption peaks of the quadrupolar doublet. The powder pattern has been analysed in terms of superposition of t...

A simple method to prepare57Fe enriched K4[Fe(CN)6] and K3[Fe(CN)6] is described. The yields of the products are much better than those reported in the literature so far. The enrichment is essential for57Fe Mössbauer investigation in a variety of Prussiate type complexes and other inorganic compounds which are conveniently prepared from K4[Fe(CN)6]...

This paper presents the results of57Fe Mössbauer Investigation of Co(en)3Fe(CN)6, a cation-anion complex where ‘en’ stands for ethylenediamine, for varlous temperatures from 300-88K. In this compound Iron exists in two oxidation states viz., Fe(III) and the abnormal Fe(IV) state. Quadrupole splitting as a function of temperature has been utilised...

Co(en)3Fe(CN)6 a mixed-valence compound, where ‘en’ corresponds to ethylene diamine, exhibits a heteronuclear charge transfer between iron and cobalt ions; both the ions being in oxidation state III. An 57Fe Mössbauer investigation confirms the creation of the rare species Fe(IV) as a result of charge transfer.

Results of 57Fe Mossbauer studies of a layered cyanide Mg(Mg((CH2)6N4)2Fe(CN)6)2nH2O as a function of dehydration are presented. The spectral features of the hydrated sample correspond to those of the low-spin Fe(II), whereas the spectrum of the dehydrated specimen is typical of the low-spin Fe(III). The variation of the spectrum as a function of w...

A simple continuous flow cryostat designed for Mossbauer investigations with liquid nitrogen in the temperature range 77–300 K is described. The cryostat is built with a perspex sample holder, glass tubes and metallic frames for mylar windows which facilitate transmission of gamma rays. A copper - constantan thermocouple is used as the temperature...