Chemistry
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Item Selenium content in meals consumed for lunch by Sri Lankans and the effect of cooking on selenium content(Ceylon Journal of Science, 2018) Kiridena, K.M.S.D.; De Silva, D.S.M.; Wimalasena, S.The selenium (Se) content in meals consumed by Sri Lankans for lunch, composed of fixed and random menus, was determined using Hydride Generation Atomic Absorption Spectrometer. The samples were obtained from five districts in Sri Lanka. The Se content (ig/kg) in meals of fixed and random menus was in the range of 48-70 and 53-60 respectively. These values are comparable to the daily requirement of Se (55 !Az/kg) prescribed by the World Health Organization and Food and Agriculture Organization of the United Nations. There is no significant difference in Se content in meals consumed by people in the districts of Kandy, Gampaha, Kurunegala, Rathnapura, and Colombo, as well as among individual households in each district. The effects of different cooking methods on the Se content indicate that the level of Se (µg/kg) in fried chicken (30.45 - 52.49) is less than that in a chicken curry (61.38 - 84.25). The percentage loss of Se during cooking for chicken, dahl (Lens culinaris) and (lotukola (Centella asiatica) were 89.6%, 84.1%, and 79.9% respectively. The present study revealed that Se content in Sri Lankan menus provides the required Se for people. However, the different methods of cooking indicate that there is a loss of Se during cooking.Item Zinc content and prediction of bio-availability of zinc in some locally grown rice (Oryza sativa L.) varieties in Sri Lanka(National Science Foundation of Sri Lanka, 2016) Herath, H.; Rajapakse, D.; Wimalasena, S.; Weerasooriya, M.K.B.Rice is the staple food in Sri Lanka and the country has a large number of traditional and improved rice varieties. Since their zinc content and bio-availability has not been studied systematically, the present study focused on the zinc content in some traditional rice varieties with high demand and also some improved rice varieties, and their predictable bioavailability. Thirty nine rice varieties from Bombuwala and Bathalagoda Regional Agricultural Research and Development Centres, grown during Yala (March - August, 2006) and Maha (September - March, 2006 ⁄2007) seasons were analysed for stable high zinc rice varieties. Mean zinc content (mg/100 g, on dry weight basis) in the varieties from Bathalagoda varied from 2.17 (Masuran) to 4.49 (Wanni Dahanala), while in the varieties from Bombuwala it varied from 2.46 (Bg 352) to 3.71 (Dahanala) with average values of 3.19 ± 0.55 and 3.11 ± 0.32, respectively. Overall mean zinc content (mg/ 100 g, on dry basis) in the two locations varied from 2.51 (Masuran) – 3.91 (Kalu Bala Wee) with an average value of 3.18 ± 0.45. The mean zinc contents varied significantly (p ≤ 0.05) with varieties. A significant variation (p ≤ 0.05) was observed with respect to the site, season, variety, site*var and ses*var in two way ANOVA, while site*ses*var showed a significant variation in three way ANOVA. The reduction of zinc and phytic acid contents in the selected fifteen polished rice varieties (at polishing rate 8 – 10 %) were 18.2 – 60.7 % and 18.8 – 40.8 %, respectively and no significant correlation was observed between zinc and phytic acid. A moderate bio-availability of zinc was shown by the molecular ratio of zinc:phytic acid and these values ranged from 8.3 – 12.5 and 9.3 – 18.9 in brown rice and polished rice, respectively.Item Selenium content in daily meals consumed by Sri Lankans-A preliminary study(Institute of Chemistry Ceylon, 2015) Kiridena, K.M.S.D.; de Silva, D.S.M.; Wimalasena, S.; Kannangara, A.T.; Weerarathna, H.P.Item Selenium content in rice consumed by Sri Lankans(Institute of Chemistry Ceylon, 2013) Mahagama, S.; de Silva, D.S.M.; Wimalasena, S.Item Effects of pretreatments on extending the self life of minimally processed Rhisomes of Lasia spinosa(Institute of Chemistry Ceylon, 2008) Liyanage, S.; Wimalasena, S.; de Silva, D.S.M.Item Quantification of arsenic and phosphorus in calcium carbide treated mangoes(Sri Lanka Association for the Advancement of Science, 2004) Haturusinghe, L.S.; de Silva, D.S.M.; Wimalasena, S.Item Effect of pretreatments on extending the shelf life of minimally processed “Ela Batu” (Solanum surattense)(Tropical Agricultural Research and Extension, 2007) Dharmabandu, P.T.S.; de Silva, D.S.M.; Wimalasena, S.; Wijesinghe, W.A.J.P.; Sarananda, S.Due to the cumbersome nature of the cleaning process and high time consumption for the preparation, most Sri Lankan housewives are reluctant to prepare Solunum surattense (Sinh. Elabatu) as a vegetable for their diet. If S. surattense is available in „ready to cook‟ form it would become a popular vegetable among Sri Lankan housewives. Studies were carried out to identify the best conditions for minimal processing of S. surattense. As pre-treatments 2% (w/v) calcium chloride solution, 0.6% (w/v) turmeric solution, 1% (w/v) vinegar solution, 2% (w/v) calcium chloride + 0.6% (w/v) turmeric solution and 2% (w/v) calcium chloride +1% (w/v) vinegar solution were used. Low density polyethylene (LDPE) pouches (gauge 150) were used to pack pre-treated samples and stored them at 8ºC. In all the pre-treated samples stored at 8ºC, Salmonella and E. coli were absent and coliform counts were at acceptable levels. Sensory evaluation of cooked pre-treated samples showed that the sample pre-treated with 2% (w/v) calcium chloride was the best. In addition to shelf life, colour, and degree of browning of the treatments were also acceptable. Treating S. surattense cut fruits with 2% (w/v) calcium chlo-ride solution before packing in LDPE pouches and storing in 8ºC found to be the best method for extending shelf-life of the fruit. The product could be kept for seven days.Item Effect of maturity on some chemical constituents of turmeric (Curcuma longa L.)(Natural Resources, Energy and Science Authority of Sri Lanka, 1988) Cooray, N.F.; Jansz, E.R.; Ranatunga, J.; Wimalasena, S.Item Selenium content in vegetables consumed by Sri Lankans(Sri Lanka Association for the Advancement of Science, 2013) Bandara, B.M.S.S.; Kannangara, A.T.; de Silva, D.S.M.; Wimalasena, S.Item Nutritional studies on rice bran incorporated cereal(Sri Lanka Association for the Advancement of Science, 2008) Bulathsighala, A.T.; Wimalasena, S.; Rajapakse, D.Rice bran is a highly nutritious by – product of the rice processing industry. In Sri Lanka it is utilized only as an animal feed. The present study reports the utilization of rice bran to produce a consumer acceptable breakfast cereal and the nutritional properties of the product. Three cereals were prepared by mixing rice flour (milled by 2 mm diameter die) with 5%, 10% and 15% stabilized rice bran from Madathawalu. The rice bran was stabilized by steaming in a pressure cooker immediately after milling. The mixture was extruded with a 2 mm die at 140 oC using a twin screw extruder. The cereal prepared was dried at 60 oC for 2 hours and sealed in double layered polythene. The sensory evaluation of the product mixed with slightly warmed milk containing sugar was carried out by 12 trained panellists at ITI using seven point hedonic scale for colour, odour, flavour, appearance. The resulting scores were analysed using the Friedman non-parametric statistical test in the SAS package. The results of sensory evaluation suggest that 10% rice bran incorporated cereal was the best product and the proximate analysis of the product (moisture, protein, fat, ash, fibre and carbohydrates) was also carried out. It was observed that the percentages of moisture, protein, fat, ash, fibre contents of the particular product (dry weight g/g) were 9.3 ± 0.3, 10.9 ± 0.5 , 4.2 ± 0.3, 1.2 ± 0.02, 0.8 ± 0.1 and 82.5 ± 0.9, respectively while those of rice were 14.3 ± 0.3, 8.1 ± 0.5 , 0.96 ± 0.13, 0.7 ± 0.1 , 0.55 ± 0.04 and 89.4 ± 0.6 and of rice bran was 8.53 ± 0.03, 16.8 ± 0.4 , 18.1 ± 0.4, 5.71 ± 0.97, 5.6 ± 0.5 and 53.1 ± 2.5, respectively. The present study reveals that a consumer acceptable cereal that is more nutritious than rice could be obtained by incorporating 10% rice bran with rice. Further, the ash (7 -12%) and crude fibre (8 -12%) content in Madathawalu were lower while moisture (8-12%), protein (12 -16%) and fat (16 -22%) were within the range reported elsewhere.