Antioxidant activity was studied for hydrolysates obtained from cowpea protein isolate by enzymatic hydrolysis using pepsin. Effects of 3 hydrolysis parameters: pH, temperature, and time were analysed using response surface methodology. A second-order polynomial model was used for predicting antioxidant activity of the hydrolysates. This model was adequate to fit experimental data and explained more than 85% of the variation. Interaction between pH and temperature was the major effect affecting antioxidant activity. Optimum antioxidant activity was observed after hydrolysis for 176 min, at pH 2.15, and temperature 38.2 °C. Under these conditions, the predicted antioxidant activity (22.69%) was in agreement with the experimental one. Degree of hydrolysis of the hydrolysate under optimum conditions was 25.70%, and the electrophoretic profile revealed the cleavage of several protein bands present in the isolate.
Authors:D. Patidar, Sonalika Agrawal, and N. S. Saxena
CdS/PMMA nano-composites at different weight percent of CdS (0, 2, 4, 6, and 8) have been prepared using solution casting method. The obtained nano-composites are characterized through the transmission electron microscope (TEM). The differential scanning calorimetry (DSC) measurements have been done on the nano-composites at different heating rates. The peak glass transition temperature is determined using the DSC thermograms. It is found that the glass transition temperature increases with the increase of CdS content up to 6 wt% and then decreases for higher weight percent (8). It is explained on the basis of molecular motion of PMMA, which is restricted when CdS is added into PMMA. An effort is also made to study the activation energy of glass transition in the case of nano-composites of different weight percent of CdS. Variation of activation energy with CdS nano-particle concentration has also been theoretically predicted by using an empirical relation. Thermal stability of these nano-composites has been explained with the help of activation energy in the glassy region.
With the aim to obtain information about atmospheric deposition of metals all over the western Himalayas (Kumaon region) using moss as bioaccumulator, a biomonitoring program was setup by financial aid of the Department of Biotechnology, Ministry of Science and Technology, Govt. of India. Present study is a part of the same monitoring program. The moss
was sampled from 24 localities of Nainital of the Kumaon Hills to indicate relative level of four metals: Pb, Zn, Cu and Cd. In summation of undertaken metals the highest 70% concentration of metals was observed in centre of the city. A gradient of decrease in metal was recorded while projecting away from city centre (zero km). A trend of metal precipitation was observed amongst seasons, viz. summer > winter > monsoon. The accumulation level of metals in the moss also varies amongst themselves, i.e. Zn > Pb > Cu > Cd. The moss metal-metal regression analysis correlation (R) exhibits that it gives significance for Pb-Zn (0.8088), Cu-Zn (0.6186) and Cu-Pb (0.5611).
Results of phase transformations, enthalpy released and specific heat of Ge22Se78–xBix(x=0, 4 and 8) chalcogenide glasses, using differential scanning calorimetry (DSC), under non-isothermal condition have been reported and discussed. The glass transition temperature, Tg, is found to increase with an average coordination number and heating rates. Following Gibbs—Dimarzio equation, the calculated values of Tg (i.e. 462.7, 469.7 and 484.4 K) and the experimental values (i.e. 463.1, 467.3 and 484.5 K) increase with Bi concentration. Both values of Tg, at a heating rate of 5 K min–1, are found to be in good agreement. The glass transition activation energy increases i.e. 102±2, 109±3 and 115±8 kJ mol–1 with Bi concentration. The demand for thermal stability has been ensured through the temperature difference Tc–Tg and the enthalpy released during the crystallization process. Below Tg, specific heat has been observed to be temperature independent but highly compositional dependent. The growth kinetic has been investigated using the Kissinger, Ozawa, Matusita and modified JMA equations. Results indicate that the crystallization ability is enhanced, the activation energy of crystallization increases with increasing the Bi content and the crystal growth of these glasses occur in 3 dimensions.
Authors:D. Saxena, P. Joos, R. Van Grieken, and V. Subramanian
The isotopes 137Cs and 210Pb were determined in sediment cores originating from the floodplain of the river Yamuna (the largest tributary in the Ganges river system, India). Sampling was done at five locations: Sharanpur (next to the Himalayan foothills), Delhi, Jagmanpur, Hamirpur and Allahabad, where Yamuna meets the Ganges. The rate of sedimentation derived from both techniques, 137Cs and 210Pb, appears to be quite similar. At the station Sharanpur the highest rate of sedimentation (5.99 cm/y) was noticed, most probably due to deforestation and other human influences in the Himalayan regions, while the lowest rate was observed in Hamirpur (2.48 cm/y). All the five cores studied showed a 137Cs peak of 1963, due to radioactive fallout, caused by weapon tests. The three upstream stations (Sharanpur, Delhi and Jagmanpur) showed a 137Cs peak due to the Chernobyl event. These measurements reflect that Chernobyl debris have been transferred to the low latitude river system across the Himalayas.
Authors:C. S. Raina, S. Singh, A. S. Bawa, and D. C. Saxena
Rice brokens were utilized in the development of pasta products. Response surface methodology (RSM) was used to analyze the effect of pre-gelatinized rice flour (from rice brokens), vital gluten, water, glycerol monostearate (GMS) and sodium alginate on the quality responses (sensory, cooking quality, rehydration ratio and solids loss) of the pasta product. A rotatable central-composite design was used to develop models for the responses. Responses were affected most by changes in rice flour and vital gluten levels and to a lesser extent by water, GMS and sodium alginate levels. The maximum sensory score (39.69), cooking quality (12.38), rehydration ratio (3.11) and minimum solids loss (15.64) were identified at 671.05 g kg-1rice flour, 242.40 g kg-1water, 74.70 g kg-1vital gluten, 2.14 g kg-1GMS and 9.71 g kg-1sodium alginate levels.