D. V. K. Samuel

Modeling of microwave assisted drying of osmotically pretreated red sweet pepper (Capsicum annum L.)

Drying kinetics modeling and effective moisture diffusivity (Deff) of osmotically dehydrated pretreated red sweet pepper (Capsicum annum L.) during microwave assisted convective drying at power levels of 0.35, 0.70, 1.05, and 1.4 W/g, air temperature of 30, 45, and 60°C, and constant air velocity of 1.5 m/s were investigated. The drying data were applied to 11 different semi-empirical mathematical models to characterize the drying kinetics and Page model provided a good agreement between experimental and predicted moisture ratio values with higher coefficient of determination (R2) and lower root mean square error (RSME) and residual sum of square (RSS). Deff decreased from 1.859×10−7 to 3.55×10−8 m2/s which is 102 to 103 times more than the previous investigations for food materials. Similarly, the activation energy decreased from 8.943 to 5.228 with decrease of drying temperature from 60 to 30°C which is due to the effect of pretreatment (osmotic dehydration). So, pretreatment can be used as criteria for faster drying thereby maintaining final product quality.

Thermal Kinetics of Colour Degradation of Yellow Sweet Pepper (Capsicum Annum L.) Undergoing Microwave Assisted Convective Drying

Experiments were conducted to study the kinetics of colour change of yellow sweet pepper during microwave-assisted convective drying at power levels of 280, 210, 140, and 70 W; temperatures of 60, 45, and 30°C; and a constant air velocity of 1.5 m/s. Colour change kinetics were determined using Hunter’s primary L, a, b values, chroma, hue, total colour change (ΔE), and browning index (BI) values. The results indicated that the degradation of a, ΔE, and hue followed zero order kinetics and L, b, chroma, and browning index followed first order kinetics. The rate constant was assumed to have Arrhenius-type dependence on temperature. Again, based on activation energy, b and hue parameters proved to be the most sensitive measures of color change, which could be taken into account during thermal processing of capsicum for getting a quality product.

Effect of Packaging Materials on Quality Characteristics of Osmotically Pretreated Microwave Assisted Dried Sweet Pepper (Capsicum annum L.)

The present study was under taken to investigate the effect of packaging materials and storage conditions on quality of capsicum (red and yellow) dried using microwave drying. The samples were heat sealed and packaged in: polypropylene (PP), Laminated Aluminum (Al) and High density polyethylene (HDPE). Then, these were stored at ambient atmosphere for four month and at every fifteen days, the quality parameters such as browning index (BI), total color difference (TCD), water activity (Aw), moisture content (MC), total carotenoid (Tc) and Sensory Score (SS) were measured. The result indicated that storage period had significant effect (P<0.05) on response variables after 45-60 days of storage except sensory score. Laminated Aluminum (Al) was least affected by the ambient environment followed by HDPE and PP having low water vapor transmission rate (WVTR).

Moisture-Dependent Physical and Physiological Properties of Accelerated Aged Pea ( Pisum sativum L.) Seeds

The present study was carried out to determine the physical as well as physiological properties of three fresh pea seed lots (cv. Arkel) with moisture content and germination percentage varying from 14.94% to 28.04% dry basis and 80% to 60% respectively. This variation in moisture content and physiological parameters was obtained using accelerated aging (40C and 100% RH). The geometric (spatial dimensions, sphericity and surface area), gravimetric (terminal velocity, true density, test weight, bulk density and porosity), frictional (angle of repose, coefficient of static friction), mechanical (compressive strength) and physiological parameters (seedling dry weight, seedling length, vigour indices, electrical conductivity and root growth parameters) were determined for the selected seed lots. The effect of moisture content on seed lots was significant (R  0.947) on physical and physiological properties of seed lots. This study may help in designing seed priming prototype suitable for pea seeds.