Browsing by Author "Prashantha, M. A. B."

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Impact of extrusion cooking on nutrient composition of a composite flour mixture developed using local grain varieties
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Perera, T. P S. S.; Godakumbura, P. I.; Prashantha, M. A. B.
Extrusion cooking is preferred over conventional cooking in the food industry because it yields high production and retains significant nutrient values in a minimum processing time. This study presents the impact of extrusion cooking on nutrient components of composite flour mixtures developed using locally available grain varieties in Sri Lanka. Formulations were developed fitting to two factor factorial design using kalu heenati (WF 13272) rice flour as the major ingredient. Further, green gram flour, black gram flour, meneri flour were composited with black seeds, sesame seeds and cinnamon in developing the final product. The flour formulations were mixed with water to produce dough of suitable consistency. These dough mixtures were extruded at 95-100 0C using a single screw extruder for a specific time. The proximate composition of samples before and after the extrusion process including carbohydrate, crude protein, crude fat, dietary fiber and ash were analyzed according to the AOAC official methods of analysis. The results showed that the extruded samples had 0.72-5.56% carbohydrates, 0.25-0.89% protein, 0.01-0.04% ash, 0.03-0.14% dietary fiber more than that of samples prior to extrusion process. Further, the extruded samples had 0.19-0.36% crude fat less than that of sample prior to extrusion process. The highest percent difference during extrusion cooking is of carbohydrate content and the lowest percent difference is of ash content. In conclusion, extrusion technology is identified as a beneficial technique in improving the nutritional composition of food products. The potential to increase nutrient availability highlights the significant impact of extrusion on the nutritional quality of foods. As this technology is of increasing concern in the food industry, further research is suggested to optimize the extrusion process and develop nutrients rich food items that meet consumer expectations for taste and sensory appeal as well.
A Study of the adsorption of oxalic acid on carbonized tea waste prepared under different heat treatment conditions
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Kumara, K. A. S. S.; Prashantha, M. A. B.; Jayaweera, C.D.
Carbonized materials are produced by various types of carbon precursors using chemical as well as physical methods. In this study, spent tea leaves, a waste and easily available low cost material, was used as the raw material for the preparation of carbonized material. The objective was to produce carbonaceous material from tea waste by application of heat and investigate the adsorption equilibrium, isothermal and kinetic studies of adsorption of oxalic acid on the carbonized tea waste. Carbonization was carried out at 350 °C for 30 min and 45 min to produce two types of carbonized tea waste. The adsorption isotherms of Langmuir, Freundlich, Temkin, and Dubnin-Radushkevich (D-R) and kinetic models; pseudo first order, pseudo second order, intra particle diffusion, liquid film diffusion, and Elovich models were used to study the behavior and characteristics of oxalic acid adsorption to the carbonized tea waste. All the studies were carried out at five different temperatures 30 ºC, 40 ºC, 50 ºC, 60 ºC, and 70 ºC. The best fit for the Langmuir isotherm suggests that the adsorption of oxalic acid onto carbonized tea waste is a monolayer adsorption process for a homogeneous surface. The maximum adsorption capacities were obtained using Langmuir isotherm. The 45 min Carbonized tea waste showed the maximum adsorption capacity of 107.5 mg g-1 at 40 ºC. The maximum adsorption capacity for 30 min carbonized tea waste is 95.2 mg g-1 at 70 ºC. The pseudo second order kinetic model well fitted with the adsorption process, having correlation coefficient values of 0.9989 and 0.9663 for 30 min carbonized tea waste and 45 min carbonized tea waste respectively suggesting that the chemisorption mechanism is predominant. The results also revealed that the adsorption of oxalic acid onto carbonized tea waste is feasible and spontaneous. However, at 350 °C, when the carbonization time was increased from 30 min to 45 min the process changed from endothermic to exothermic with declined randomness. The presence of functional groups hydroxyl, carboxyl, carbonyl and amine in the carbonized tea waste was confirmed by FTIR studies. The surface characteristics such as the roughness, presence of micropores and mesopores as revealed by SEM-Eds technique may cause a favourable adsorption. In spite of the required high carbonization temperature and time heat treated carbonized tea waste points out to have adsorption characteristics similar to commercially available activated carbon according to this study