Browsing by Author "Somarathna, A.P.H."

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    Effects of Tannase in Comparison to Viscozyme on Physicochemical Properties and Sensory Properties of Cold Water Soluble Instant Tea
    (Uva Wellassa University of Sri Lanka, 2014) Somarathna, A.P.H.
    Developing turbidity in cold water soluble instant black tea is undesirable. Though various enzymatic treatments have been invented to overcome this problem their effects on physicochemical properties of cold water soluble instant black tea are not known. This experiment was conducted to investigate the effects of optimized tannase and viscozyme enzymes treatments on physicochemical properties of cold water soluble instant black tea. A preliminary study was conducted to optimize the level of enzyme. Samples of hot water extract black tea were treated separately with five different levels (0.1-0.5%) of tannase and viscozyme enzymes based on the total solid in the extract while maintaining the temperature at 45°C for 40 min. Then the samples were heated to 90°C and after cooling to the room temperature samples were centrifuged at 3500 rpm for 10 minutes. Turbidity, color and brightness of supernatant were measured. Further supernatant were analyzed for theaflavin and thearubigins and total polyphenol content. Then samples of hot water extract of black tea were treated with optimized enzyme levels of individual enzymes and with their combinations. Supernatants were obtained using the same procedure and freeze dried. These samples were analyzed for color (L, a, b values), brightness, cold water solubility. Their theaflavin, thearubigins and total polyphenol content were also analyzed. Sensory properties of the samples were evaluated using a trained tasting panel. Each experiment was repeated thrice. Data were statistically analyzed by performing Duncun Multiple Range Test (P<0.05) and sensory evaluation data were statistically analyzed by performing Freidman test using Minitab 17. According to the results of preliminary study .Color of tannase treated sample (10.10+0.61) was significantly higher than that of viscozyme treated sample (8.37+0.52) but its brightness (11.89+1.18) was significantly less than that of viscozyme treated sample (13.47+0.99). Furthermore, turbidity of viscozyme treated sample (4.85+1.20) was significantly lower than that of tannase treated sample (16.87+2.45). Lowest turbidity levels were evident at enzyme level of 0.3% for both tannase (16.86+2.2) and Viscozyme (4.85+1.20).
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    Effects of Tannase in Comparison to Viscozyme on Physicochemical Properties of Cold-Water-Soluble Instant Tea
    (Uva Wellassa University of Sri Lanka, 2019) Somarathna, A.P.H.; Perera, G.A.A.R.; Piyasena, K.G.N.P.; Edirisingha, E.N.U.
    Developing turbidity in cold-water-soluble instant black tea is undesirable. Though varies enzymatic treatments have been invented to overcome this problem their effects on physicochemical properties of cold-water-soluble instant black tea are not known. This experiment was conducted to investigate the effects of optimized tannase and viscozyme enzymes treatments on physicochemical properties of cold-water-soluble instant black tea. Samples of hot water extract of black tea were treated separately with five different levels of tannase and viscozyme (0.1-0.5%) based on the total solid in the extract maintaining the temperature at 45oC for 40 min. Then the samples were heated to 90oC and after cooling to room temperature they were centrifuged at 3,500 rpm for 10 min. Supernatants were analyzed for turbidity, color, brightness and total polyphenol content. This experiment was repeated thrice. Data were statistically analyzed by performing Duncun Multiple Range Test (P<0.05). Lowest turbidity levels were evident for both Tannase (16.86±2.2) and Viscozyme (4.85±1.20) at 0.3% enzyme level. Total polyphenol content (g/100 mL) of tannase treated sample (0.78±0.13) was not significantly different to that of viscozyme treated sample (0.64±0.02). Color of tannase treated sample (10.10±0.61) was significantly higher than that of viscozyme treated sample (8.73±0.52) but its brightness (11.89±1.18) was significantly less than that of viscozyme treated sample (13.47±0.99). Nevertheless, turbidity of viscozyme treated sample (4.85±1.20) was significantly lower than that of tannase treated sample (16.87±2.45). It can be concluded that tannase can improve color of cold-water-soluble instant tea and viscozyme improves clarity of instant tea at 0.3% enzyme level. It should be further studied the potential of combine treatment of enzymes in improving overall physicochemical properties of cold-water-soluble instant tea.
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    Prediction of Crop Yield for Rice, Tea and Sugarcane in Sri Lanka using Sunspot Number
    (Uva Wellassa University of Sri Lanka, 2021) Rajakulathunga, R.K.C.S.; Bulathsinghala, A.T.; Nilmini, K.A.C.; Wijesekera, J.V.; Somarathna, A.P.H.; Hansani, V.A.C.; Udani, H.R.S.; Perera, B.K.S.; Senarath, W.C.S.; Ranasinghe, D.A.P.D.P.
    In this research, the relation of crop yields to sunspot number for tea, rice and sugarcane was studied in Sri Lanka located between latitudes 50 55⸍ N and 90 51⸍ N and longitude 790 41⸍ E and 810 53⸍ E. Parametric analysis was carried out to obtain historical coefficients for solar activity index and crop yield data, using observed yields with time, sunspot number, and cultivated area as input variables. Data on the total cultivated area (ha) with yield (hg ha-1) of rice, tea and sugarcane from 1961 to 2016 were statistically analyzed. Data were obtained from Food and Agricultural Organization, Statistics Division (FAOSTAT) and online data on yearly mean total sunspot number was retrieved from World Data Center – Sunspots Index and Long term Solar Observations (WDC - SILSO). To predict crop yield, a multiple linear regression model was used which best described the relationship between sunspot number and crop yield variables using Minitab Software. The coefficient of variation depicts the relative deviation in yields of the various crops, with sugarcane yields being the highest (29.4%) and rice yields being the lowest (23.7%). During periods of maximum solar activity in the years 1968, 1989, and 2000, yields for tea and sugarcane decreased significantly while yields for rice indicated an increment. Besides, yields for tea and sugarcane increased significantly and yields for rice decreased during periods of minimum solar activity in the years 1976, 1996, and 2008. The model explained 91.93% of yield variance for rice and 82.16% of yield variance for tea also 51.51% of yield variance for sugarcane. This overall study indicates that there is a considerable contribution to yield from SSN and the pattern of yield that varies with SSN can also be identified. Keywords: Crop yield prediction; Multiple linear regression; Solar activity; Sunspot number