Browsing by Author "Wijesekara, I."

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Effect of dehydration temperature, time and blanching methods on the sensory properties of an herbal tea developed from Moringa oleifera leaves
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wickramasinghe, W.Y H.,; Wickramasinghe, I.; Ariyasinghe, H. A. E. N.; Wijesekara, I.
Moringa oleifera is a highly nutritious plant which can be used as a good source of nutrition and leaves have been found to contain high amounts of vitamins, minerals, proteins and fiber. The main objective of this study is to explore the use of Moringa oleifera leaves, to produce an herbal tea with acceptable sensory properties, by using different dehydration temperatures, time and blanching methods which can be used in the Sri Lankan market. According to AOAC procedures the initial moisture content (%) of fresh leaves was found to be 78.17 ± 1.57 (dry basis). Six sets of samples were prepared where temperature and time combinations were; 600C 4 h 30 min, 650C 3 h, 550C 6 h for unblanched samples and; 600C 5 h 30 min, 650C 4 h and 550C 6 h for the steam blanched samples. The gross yields of the dried leaves to its initial weights were 22.86%, 20.88%, 23.62%, 19.18%, 15.21% and 14.97% respectively. The moisture content of the dried leaves ranged from 2.09±0.17 to 5.36±0.06. The colour values L*, a*, b* ranged from 16.83 ± 3.02 to 30.2 ± 3.32, -1.93 ± 0.46 to - 6.41 ± 0.79 and 5.1 ± 1.29 to 15.49 ± 1.29 respectively. These samples were given to a trained panel of tea tasters for the sensory evaluation and sample 5 (steam blanched, 650C 4 h) was selected as the sample with the best sensory attributes. These samples were evaluated using a 5-point hedonic scale, by a semi-trained panel of 35 assessors and data were analyzed using the MINITAB statistical package using Friedman test. According to the statistical analysis, sample 5 showed the highest score. The brew of unblanched leaves was giving harsh unpleasant characters whereas the steam blanched samples were giving a pleasant taste.
Important physiochemical properties of selected underutilized yams and development of cup-cakes using “Raja ala” (Dioscorea alata) flour
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Gunasekara, G. D. M.; Wickramasinghe, I.; Wijesekara, I.
Sri Lanka has many underutilized yams with high nutritional potential. Most of these underutilized species have lost their significance among the present generation due to many reasons such as urbanization and changing food habits. The objective of this study was to evaluate the nutrient composition, and physiochemical properties of five selected underutilized yam varieties in Sri Lanka; “Raja ala”, “Kidaramala”, Aralog-green, Aralog- red, and “Katu ala”. In addition, cup-cakes were developed using “Raja ala” flour with food gums including pectin 0.3% (w/w based on flour). Yams were collected, peeled, dried, ground, and sieved to obtain fine flour powder. The proximate analysis was carried out to calculate the moisture content, crude protein, total fat, total carbohydrate, and total ash. Then, the texture profile of cupcakes including hardness, deformation, adhesiveness, cohesiveness and springiness were analyzed. The moisture content of both flesh and peel from each five varieties varied between 6.20% and 7.82% (dry weight, w/w). All five varieties were low in fat content and highest was recorded in “Raja ala” (1.10 ± 0.01%), whereas the lowest was recorded in “Katu ala” (0.27 ± 0.16%). The crude protein content of “Raja ala” and Aralog-green were 4.62 ± 0.59% and 3.89 ± 0.57%, respectively. The highest ash content was recorded in “Kidaram ala” (5.88 ± 1.30%) and the lowest was recorded in Aralog-red (1.65 ± 0.04%). By incorporating pectin, gluten free cupcakes were prepared with “Raja ala” flour. According to the results, the hardness at cycle 1 and cycle 2 were 6065.00 g and 4335.00 g respectively. Also, the stringiness length, cohesiveness, adhesiveness and springiness were 14.63 mm, 0.31, 11.30 mJ and 36.46 mm respectively. Furthermore, the analysis of antioxidant potential and total phenolic content of both peel and flesh of the above selected yams, flour properties, and sensory qualities of developed cup cakes are in progress.
Isolation of laccase producing fungi: Aspergillus niger from Sri Lankan textile wastewater effluents and its potential applicability on decolorization of an azo dye: CI Direct Blue 201
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Ekanayake, E. M. M. S.; Wijesekara, I.; Manage, P.M.
The complex aromatic structural nature of synthetic dyes show resistance to natural oxidation processes and persist in the surface water and sediments for a long time. The existing physical and chemical treatment methods are costly and create secondary pollution. Therefore, the present study was focused on the degradation of an azo dye: CI Direct Blue 201 (DB 201), by myco-remediation. Aspergillus niger, a filamentous fungus, was isolated from textile wastewater effluent site in Sri Lanka and pure cultures were maintained on Potato Dextrose Agar (PDA) plates. Four cylinders (10 mm diameter in each) of actively growing A. niger cultures were cut and inoculated into mineral salt medium consisted of 50 mgL-1 DB 201 dye. All the experiments were carried out in triplicates, while controls were maintained without addition of the fungus. Flasks were incubated at 28 °C for seven days with shaking at 100 rpm. Three milliliters of sample aliquots were removed at 6 hrs intervals, centrifuged and the changes of the absorbance in the supernatant was analyzed through UV-Vis spectrophotometer at 570 nm. The laccase activity was determined by measuring the increase in the optical density at 420 nm. The reaction mixture for laccase assay contained 5 mM of 2,20-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) in 50 mM sodium acetate buffer (pH 4.5) and 50 μL of decolorized dye solution (ε420 = 36000 M−1 cm−1). Decolorized dye sample was analyzed through Fourier Transform Infrared (FTIR) Spectroscopy. A Bio-sorption test was carried out by providing the same incubation conditions using 3-day-old live and autoclaved fungi. The control without adding fungus, remained the same without showing any decolorization. The enzyme activity of laccase has increased during the decolorization processes from 18 Uml-1 to 254 Uml-1. The changes of the FTIR spectra relevant to the N=N Vibration (1723.3 cm-1), S=O Stretching (1227.3 cm-1) and N-O Stretching (742.88 cm-1) indicated the changes of the initial DB 201 dye structure after the treatment by A. niger. Furthermore, the bio-sorption assay by live (100%) and autoclaved fungi (12 ± 2%) confirmed the decolorization and the degradation of DB 201 dye would be based on the metabolic activity of the fungus rather than surface adsorption. Therefore, the present study emphasizes the potency of A. niger as an eco-friendly candidate for degradation of azo dyes. Further studies regarding the application of enzymes for real textile dye treatments are currently in progress.
Textural profile analysis of granulated cassava pearls of two cultivars treated with conventional and microwave heating
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Bulathgama, B. E. A. U.; Wickramasinghe, I.; Wijesekara, I.; Somendrika, M. A. D.
Cassava (Manihot esculenta Crantz) is an important food source in tropical countries, and it is a readily available root crop variety in Sri Lanka as well. Yet processed cassava (flour) is underutilized. The objective of this study was to identify the effect of conventional and microwave heating on two selected cassava cultivars namely; Kirikawadi and Muthukawadi granulated flour pearls. The granulated cassava pearls were made by the moistening and mechanical shaping of the flour by adding 50% water by weight. Then the pearls of both cultivars were subjected to conventional heating in normal cooking oven at 1000C for 20 minutes, and microwave heating in mid power for 5 minutes. The obtained pearls were then analyzed for the texture profile analysis. The morphology of flour granules were observed by microscopic image projection, where the two cultivars showed no observable difference in their granular shapes. The two cultivars; Kirikawadi and Muthukawadi flour had an initial moisture content of 8.23% and 9.00% respectively and after moistening the moisture contents were 41.95% and 38.59% respectively. After the heat treatments, the texture profiles including hardness, deformation, adhesiveness, cohesiveness and springiness were analyzed for all the samples. According to the results, the highest hardness was obtained by microwave heating method for both cultivars. The hardness of conventionally heated varieties were 200.00 g for Kirikawadi and 235.00 g for Muthukawadi, and microwave heated varieties were 19780.00 g and 10390.00 g respectively. The deformation has changed with the heating method, where the deformation of both conventionally heated varieties varied, between 0.64 - 0.66 mm and microwave heated varieties showed 1.38 mm (Kirikawadi) and 1.90 mm (Muthukawadi). Other texture properties; adhesiveness, cohesiveness and springiness showed no significant variation (P>0.05) either with cultivar or heating method. According to the results of the study, the microwave heating is suggested to be more preferable over the conventional heating method, as modified forms of this type of starches have higher demand in the novel processed food industry.
Utilization of Cinnamon (Cinnamomum verum) and Turmeric (Curcuma longa) to develop novel low glycemic index bread products
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Wijewardhana, U. S.; Jayasinghe, M. A.; Wijesekara, I.; Ranaweera, K. K. D. S.
Type II diabetes is a major healthcare problem in the world affecting almost all households and economies. Diet is a crucial factor in the etiology of Type II diabetes and therefore, dietary interventions can be used effectively to prevent and manage the disease. Bread is a staple among all communities which is high in carbohydrates and glycaemic index. Regular consumption of high-glycaemic foods can lead to the onset and development of Type II diabetes. Hence, innovating low-glycaemic indexed bread products is a timely intervention. The study aimed to develop novel low-glycaemic bread products incorporating minuscule amounts of Cinnamon (Cinnamomum verum) and Turmeric (Curcuma longa) powder without affecting palatability and sensory properties. Initially, breads were formulated with different percentages of Cinnamon and Turmeric powder and separate sensory evaluations were carried out to select the best ones according to sensory perceptions. A semi-trained sensory panel consisting of 30 panellists was used for sensory evaluations and products were evaluated for their Appearance, Aroma, Texture, Taste, and Overall acceptability. Statistically selected best bread products proceeded to human study to calculate the glycaemic index along with a control. Twelve healthy adults were selected for the study on a voluntary basis and finger prick blood samples were drawn in a 2-hour time window, upon ingestion of test foods. Glycaemic index values were calculated using D-glucose as a standard. Calculated glycaemic index values were 57.1±14.94, 45.06±12.34, and 42.98±13.9 for control bread, Cinnamon bread, and Turmeric bread respectively. Thus, it could be concluded that the incorporation of Cinnamon powder and Turmeric powder in minuscule amounts has hindered the glycaemic impact of wheat bread reducing the glycaemic index from the ‘medium GI (56-69)’ to low GI (≤55) category. The study provides future insights into reducing the glycaemic impact of a diet incorporating functional ingredients. Future research is needed to explore whether the addition of antidiabetic plant ingredients could reduce the glycaemic impact of other high glycaemic foods. These novel products will be greatly beneficial to the diabetic community and the general public and will be highly marketable.