Science and Technology Degree Programme (SCT)

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Kinetics Modeling of Partial Degradation of Carbofuran by Pyrite
(Uva Wellassa University of Sri Lanka, 2011) Dhanasekara, S. A. K. M.
The zeta potential of pyrite and pyrite-carbofuran suspensions was examined as a function of pH and the chemical kinetics of carbofuran was examined in the presence of pyrite as a function of pH and adsorbent loading. The pHiEp of pyrite was around 1.70 when inert environmental conditions were maintained. In the presence of carbofuran, the pHIEp shifted from 1.70 to —3 and the zeta potential has increased indicating direct surface interactions. The carbofuran degradation was also evidenced by time resolved IR spectroscopic measurements. Conventional kinetic experiments showed that the degradation is pseudo-first order with respect to carbofuran concentration. When the initial pyrite loading is increased by about 10 fold, the reaction order of carbofuran degradation has transformed from 0th to pseudo 1st order indicating a surface mediated mechanism. This mechanism of carbofuran degradation is largely ascribed to a Fenton like process. In the presence of pyrite at acidic pH, the carbofuran degrades via two routes: cleavage of the C-N bond forming carbamate and 2,3-dihydro-2,2-dimethyl benzofuran-7-al formate, and cleavage of the C-0 bond forming methylamine and 2,3-dihydro-2,2-dimethylbenzofuran-7-ol. The resulted carbamic acid is unstable and, therefore rapidly degraded to methylamine and CO2. In agreement with mass spectroscopic data, a simple kinetic model was proposed as required for design of a unit process in drinking water treatment.
Development of Cereal Incorporated Yoghurt
(Uva Wellassa University of Sri Lanka, 2012) Ramawickrama, P.
Yoghurt is a fermented milk products obtained from coagulation of milk by the agency of organisms of types Streptococcus thermophillus and Lactobacillus bulgaricus. Lactobacillus acidophillus may be present. It is known as highly nutritional food item having more health benefits. Cereals are the edible seeds (grains) of the plants of the grass family (Grameneae). Cereals are considered as healthier, and provide staple food for most Asians. Incorporating both nutritional sources, this study was aimed to develop a ready — to — serve cereal incorporated yoghurt as a new yoghurt product, while adding value to local cereal varieties such as Rice (Oryza sativa) and Finger millet (Eleusine coracana). The study was carried out in four major phases, Background Study, Preliminary trials, Experimental trials and the Final analysis where shelf life determination, proximate analysis and cost analysis were done. The best formulae for cereal incorporated yoghurt were, 4% of rice flour incorporated yoghurt (R4) and 8% of flour combination incorporated yoghurt (RF2). Both yoghurt types had higher SNF content and lower fat content than plain milk yoghurt. Basic raw material cost for the production of one R4 yoghurt cup is LKR. 6.14 and that for RF2 yoghurt is LKR. 6.84. The shelf life of R4 yoghurt was 9 days and for RF2 yoghurt it was 11 days. Both were obtained without the addition of preservatives.
Use of Thermochromic Pigments to Devolop a Freshness Indicator for Freeze Stored Foods
(Uva Wellassa University of Sri Lanka, 2012) Jayarathna, C.G.
Freezing is used for the purpose of preserving perishables and results in fewer undesirable changes in qualitative and organoleptic properties than other methods of preservation. Use of indicators to maintain the freshness of these freeze stored foods has numerous advantages in the sense of marketing. The potential of sensor technologies, indicators (including integrity, freshness and time-temperature (TTI) indicators) and radio frequency identification (RFID) are evaluated for potential use in meat and meat products. Thermochromic pigments have a greater contribute for time temperature indicators they are the substances which change the color due to temperature changes. Use of thermochromic pigments, to develop a freshness indicator is one of the modem trends of marketing, hence the purpose of this thesis to find the suitable mixture of pigments, which can be used to detect whether poultry and meat products are properly refregirated under freezing conditions. A photoactivated time-temperature indicator is based on a leuco base system. This is developed by thermally insensitive, white ("inactive") leuco base (or a mixture of such leuco bases) is mixed, preferably in a polymeric matrix, with a material that generates acid upon exposure to light. Photoexcitation, preferably by UV or near UV light, causes the formation of a thermally sensitive, color- forming ("active") product. Following this activation step, a progressive color development occurs at a rate that increases with temperature. The best solvent mixture for the polymeric gel is ninety five ethanol in water mixture, and dried, UV activated labels readily develop deep green color from fainty gray color, when the temperature exceeds 12°C after four hours. Fifty percent of reflectivity at 632 nm was obtained after 4 hours at 12°C. The indicator is useful for monitoring the freshness of perishable products, particularly those stored at sub ambient temperature.
Thermally Treated Sri Lankan Graphite as an Anode Material for Rechargeable Lithium-Ion Battery
(Uva Wellassa University of Sri Lanka, 2012) Rupasingha, M.N.
Graphite is a typical layered compound that consists of hexagonal sheets of sp2-carbon atoms weakly bonded together by Vander Waals force. Therefore, it is an excellent lithium intercalation compound as anode materials in Lithium ion rechargeable batteries (LIB). Reversible intercalation and deintercalation are key process operating in lithium ion cells by high capacity (337 mAh/g) and low potential (0.1 — 0.3 V vs. Li+/LI). Natural graphite would be a strong candidate since it is cheap. The surface chemistry of the graphite can be effectively modified by mild oxidation in air by forming dense oxide layer which is important for formation of a stable and protecting solid electrolyte interface (SEI) during initial few cycles non-toxic and widely available. Sri Lankan natural graphite is a potential candidate for anode material due to high purity, low cost and wide availability Therefore, with in this study aims to develop performance enhanced low-cost anode material based on thermal oxidation of different structural types of vein graphite from Bogala and Kahatagaha-Kolongaha mines. Then, four structural types, namely coarse flakes of radial (CFR) graphite, coarse striated-flaky (CSF) graphite, needle-platy (NPG) graphite and shiny-slippery-fibrous (SSF) were categorized in both mines. After preparing powdered samples (<53 Jim) were used for thermal oxidation at 550°C in a Muffle Furnace (OT-HTMF 05) under air for 6hours. What more both treated and untreated samples were used to characterize electrically by using four-probe d.c. conductivity method at room temperature & used to define graphine surface is modified by carbonyl, carboxyl and hydroxyl functional groups. As a result of this study, the absence of such absorption peaks in untreated graphite reveals the formation of carbonyl group on periphery of hexagonal carbon basal plane. And also the d.c electrical conductivity of both types of graphite has increased slightly after oxidation.
Screening of Leafy Vegetables of Family Cruciferaceae for Heavy Metal Contamination
(Uva Wellassa University of Sri Lanka, 2012) Ruzaika, N.F.
As human activities increase, especially with the application of modern technologies, pollution and contamination of the human food chain has become inevitable. Intake of heavy metal-contaminated vegetables may pose a risk to the human health. Vegetables can hyper accumulate metals from the soil and air from polluted environment. Many studies have emphasized the need of this type of investigation in Sri Lanka. In Sri Lanka, accumulation of heavy metals in different sources and vegetables has been widely reported. This investigation demonstrates screening of five leafy vegetable species of family Cruciferaceae, for heavy metal contamination. Vegetable samples (Brassica oleracea (Cabbage), Brassica oleracea (Kohlrabi), Brassica oleracea (Cauliflower), Raphanus sativus (Radish), and Brassica oleracea (Collard Greens)) where collected from the market sites of Nuwara- Eliya, Badulla and Bandarawela areas of Sri Lanka. Collected test vegetable samples were tested for Cu, Mn, Zn and Pb contamination. Samples were prepared by following dry ashing technique and an Atomic absorption spectrometer was used to analyze the prepared samples. A control test was performed by Invitro cultivation of test vegetable varieties. From the estimated concentration of the Lead of selected vegetable varieties can be suggested that the consumption of average amounts of these contaminated vegetables poses a health risk for the consumers as the values obtained are upper the WHO limit for Lead intake and the estimated concentration of Cu, Zn and Mn of selected vegetable varieties can be suggested that the consumption of average amount of these contaminated vegetables do not pose a health risk for the consumers as the values obtained are below the WHO limits. The study concludes that the results of statistical analysis show that heavy metal concentrations varied among the test vegetables and areas and the consumption of average amounts of these contaminated vegetables poses a health risk for the consumers.
Tribological Behavior of Sri Lankan Quartz
(Uva Wellassa University of Sri Lanka, 2012) Ruwanmalee, K.P.E.W.
Quartz is the most common mineral on the face of the Earth. It is frequently is the primary mineral, >98%. It is also the most varied in terms of varieties, colors and forms. [4].Owing to its high thermal and chemical stability and abundance, quartz is widely used in many large-scale applications related to abrasives, foundry materials, ceramics, and cements.[1] However industrial use of Sri Lankan quartz has not been tried so far at a commercial scale. It is high erosive wear resistance should be investigated before it applying to the industrial applications. Thus it can be a advantages for the industry because can use low natural quartz for the applications. The main objectives of this study were to investigate the tribological properties of natural quartz, especially slurry erosive wear resistance. Furthermore, it was aimed at investigating the tribological properties of Sri Lankan quartz and fills the gap of knowledge on tribological properties of Sri Lankan quartz. Experiments were performed to compare the resistance to erosion under a fixed set of experimental conditions. Natural quartz (Rose, Smoky, Milky, Citrine), Synthetic quartz were used as sample materials. Synthetic quartz was used as the controller material to ensure test conditions. For this study simple slurry pot tester was constructed and SiC and distilled water were used as the erodent particles and the fluid respectively. Erosion of the specimens was determined as a function of time by measuring the mass loss. This study showed that Sri Lankan natural quartz specimens are comparable or having a wear resistance half of the synthetic quartz wear resistance. Especially the citrine show considerable lower slurry erosion hence higher resistance for wear than other natural quartz types (Rose, Smoky, and Milky). When considering the fact that Sri Lankan quartz is abundant having no commercial value, this study will possibly open industrial opportunities for those cheaper but better wear resistive materials. Further mineralogical and tribological investigations are being carried out in order to explore the potentiality of them for industrial applications.
Fumigant and Contact Toxicity of Selected Underutilized Plants Against Grain Storage Pest Tribolium castaneum(Herbst)
(Uva Wellassa University of Sri Lanka, 2012) Premarathna, V.
Since Sri Lanka is a developing and agriculture based country, it is crucial to minimize the post-harvest losses. The insect infestation of stored grains and their products is a serious problem. Nowadays controlling insects is mainly practiced by using synthetic insecticides and fumigants. But their widespread use has led to some serious problems. This study was carried out to screen the contact and fumigant toxicity of underutilized and highly abundant herbaceous plants on storage pest Tibolium castaneum. For this study methanol crude extract of dried leaves and fresh flowers of Bidens sulphurea, Helliunthus annuus, Tagetes erecta and Tithonia diversifolia were obtained and experiments were conducted with Randomized Complete Block Design and two factor factorial designs. Contact toxicity and fumigant toxicity were tested for T castaneum with five different doses and three different doses respectively. Highest mortality values were found even at the low doses in T. erecta dry leaves, H. annuus dry leaves and T. erecta flowers for contact toxicity. T erecta dry leaves and T diversifolia fresh flowers show high fumigant toxicity. T. erecta dry leaves show\qne highest both toxicity effects on T castaneum. Any mortality was not observed in control, even without food and air supplement. According to the ANOVA, there was no significant interaction effect between dose and crude type to the mean mortality % (p > 0.05). The best selected plants were re¬examined under randomly selected dose series to calculate the median lethal doses (LD50 value) using probit analysis. LD 50 values of T erecta dry leaves, H. annuus dry leaves and B. sulphurea fresh flowers are 13.129 pg/cm2, 38.925 1.tg/cm2 are 51.716 p,g/cm2 respectively for contact toxicity. LD50 values of T erecta dry leaves and T. diversifolia fresh flower were 109.044 i.tg/cm2 and 196.368 gg/cm2 respectively for fumigant toxicity. Hence those two types of extracts can be used in developing a fumigant to eradicate the infestation of Tribolium castaneum.
Development of Microbial Biofilms for Better Growth of Eucalyptus grandis Plants
(Uva Wellassa University of Sri Lanka, 2012) Perera, K.P.V.K.
Eucalyptus is the highest grown forest plantation species worldwide (Rhoades and Binkley, 1996) and in Sri Lanka, 20 percent is represented by Eucalyptus grandis (Bandarathilake, 1996). At present sites available for reforestation in Sri Lanka are generally poor in nutrient status and fertilizer application is required for better growth of seedlings (Bandarathilake, 1996). It has being reported that by increasing the soil organic carbon stock, in other words increasing soil carbon sequestration, crop yields could be increased. Microorganisms play a major role in sequestration of soil carbon. If we can use such carbon sequestering microorganisms in biofilm biofertilizers to improve soil organic carbon content, that will be an advantage as these may have a greater potential to boost the level of soil organic carbon and to enhance the growth of crops in an environmental friendly manner. This study focused on the fabrication of a biofilm biofertilizer for the better growth of Eucalyptus grandis plants in a nursery, which could be cost effective and environmental friendly. According to the final outcomes of the study, it is clear that Medawelagama and Pelgahatenna Eucalyptus grandis plantation sites contain the highest organic carbon content among the four sites. When comparing the organic carbon content of two soil layers ("0-15cm" and "15-30cm"), it was statistically proved that "0-15cm" soil layer contains significantly higher organic carbon content than "15-30cm" soil layer. Seven bacteria and three fungi types were isolated during this study. Although all the seven isolated bacterial types were combined and cultured with the three isolated fungal types separately to facilitate biofilm formation, only two combinations were succeeded in formation of biofilms with high intensity. There is a positive effect from the fabricated biofilms ("biofilm 3" and "biofilm 5") for the growth of Eucalyptus grandis nursery plants. But further studies are required to understand the continuous effects of the fabricated biofilms on the growth and productivity of Eucalyptus plantations including their soil organic carbon content.
Changers of Selected Macro/Micro Nutrients in Minimally Processed Banana Blossom Under the Low Temperature (8o C) Storage
(Uva Wellassa University of Sri Lanka, 2012) Dissanayake, D.M.A.B.
Minimally Processed or fresh-cut fruits and vegetables are a rapidly developing segment of the fresh produce industry. These products are manufactured by washing, sorting, peeling, slicing and packaging with plastic film or in plastic trays wrapped with films. Minimally Processed (MP) fruits are new forms of product marketing intended to meet the consumer's desires for convenience and fresh-like quality. Fresh cut products are living cells and they have highly nutritional content than other foods items. Because of that the preparation method, storage condition, storage temperature, packaging material mainly affect to the nutritional quality degradation of the fresh cut products. Effect of chemical treatment and the storage condition to nutrient depletion within their shelf life period was analyzed. Banana l?lossom grow on the end of the stem holding a cluster of bananas it considered an Asian or tropical vegetable.29 cultivars can found in Sri Lanka. Banana processing involved washing in cool (8 °C) distilled water, Chlorine water (100ppm) and cleaned water. Then subjected to CaC12 solution (5g/L).Packaging was done by using LDPE bags and stored under refrigerator condition. Samples of banana flower were analyzed for proximate composition ( protein, total dietary fiber, vitamin C and Anti-Oxidant) following the standard methods published by Association of Official Analytical Chemists (AOAC, 1995). Protein was determined by Kjeldahl method (Kjeldahl, 1883), and thereafter a conversion factor of 6.25 was used to calculate the total nitrogen to crude protein. Total dietary fiber (TDF) was determined according to the Ceramic Fiber Filter Method AOAC Official Method 962.09 (1982).Vitamin C content was determined by the redox titration method using iodine solution. The antioxidant activity was determined by the DPPH (2-2'- diphenylpicrylhydrazyl) assay. Embul kesel blossom have High protein content (19.11 +0.50 g/100g) and Vitamin C content (7.96+0.04 mg/ 100g). Koikuttu kesel have high dietary fiber content than other cultivars. DPPH Radical Scavenging capacities of banana blossoms are high in Embul kesel (21.02 + 0.31 ppm).The most of the Nutrient is slightly reducing during Processing and Storage time period. Therefore, needs develop well processing methods and storing condition to preserve nutrient of minimally processed Banana blossom.
Development of Li1/3 Ni1/3 Mn1/3 Co1/3-x Mx O2 Cathodes for Li-ion Battery
(Uva Wellassa University of Sri Lanka, 2012) Perera, M.D.N.
Li-ion batteries are widely used in portable electronic industry, and have been considered for large scale applications such as electric or hybrid electric vehicles. Today the rapid development in electronics industry needs better batteries with higher energy storage, lower capacity decay, lighter weight and low cost. The high cost of the LIB is mainly due to the high cost of cathode materials. This study is mainly focused on the electrochemical performance of a Li1/3 Nil/3 Mni/3 Col/3-x Mx 02 type cathode material. Ni1/3 Mnu3 Co1/3-x Mx 02 powder was successfully synthesized by employing the wet chemical powder preparation method: Glycine-nitrate process. The powder was calcinated at 650°C for two hours in air and using that powder pellets were prepared by uniaxial cold pressing technique. Then the green pellets were sintered in a furnace at 1000°C for two hours in static air. Before measure the electrical conductivity the pellets were gold pasted and heat treated at 730°C for one hour to make the better contact with Pt electrodes. The electrical conductivity of sintered pellets was measured by DC four-probe technique. Flexible electrodes were fabricated for selected materials via tape casting. Tape casting was performed employing the doctor-blade technique. In this process, oxide powder was mixed with polyvinylidene fluoride (PVDF) binder and synthetic graphite in proportions 1: 0.25: 0.10 by weight. Those proportions were mix and blend with propylene carbonate (PC) corresponding to 40% of active material weight and dissolved with acetone. Slurry was stirred in magnetic stirrer and poured in to manual tape caster. The electrical conductivity of the prepared electrodes was measured by van der Pauw technique. Then the electrical conductivity of selected best materials was enhanced by introducing synthetic graphite and Sri Lankan natural graphite as a conductivity enhancer. This study shows that the possibility of using Li1/3 N11/3 Mn1/3 C01/3-x Mx 02 type materials for LIB cathode. According to the observed data Lit/3 Ni1/3 Mn1/3 C01/3-x Mg0 22 02 and Lim Nil/3 Mn1/3 Col/3-x Zn0.11 02 materials got the most sufficient conductivity values that suitable for cathode. As a conductivity enhancer for cathode fabrication Sri Lankan natural graphite also can be used instead of synthetic graphite.
An Enhancement of Effeciency of Solid-State Dye-Sensitized Solar Cell by Coupling Two Metal Centered Dyes.
(Uva Wellassa University of Sri Lanka, 2012) Rubasinghe, S.H.
After nearly decade of extensively investigate on dye — sensitized photo electro chemical solar cells based on the nano structured semiconductor films, the dye-sensitized solar cells have begun to receive considerable attention as the promising system for conversion energy. However, solid-state solar cells aroused much attention due to capability of usage in electronic devices than dye sensitized solar cells with liquid electrolyte. Several types of organic dyes, natural pigments, various types of hole-conductors have been used by aiming uplift of performance of the n-semiconductor dyelp-semiconductor (NDP) cells. The main objective of this work was to enhance the photo performance of the solid state Dye sensitized solar cells by coupling two metal centered dyes.In there used the ruthenium( I]) polypyridyl complexes.those are cis-bis(isothiocyanato)-bis(2,2'- bipyridy1-4,4'-dicarboxylato)ruthenium(II) (N719) and triscarboxy-ruthenium terpyridine [Ru(4,4',4"-(COOH)3-terpy)(NCS)3] (Black dye) as the metal centered dyes. Experiments were carried out by changing the cell configuration according to the dye immersing sequence.TiO2 semiconductor was used as the anode of the cell and the CuI was used as the hole collector or the p type semiconductor. In there mainly got the results for the cell configurations that having CuIIN719ITiO2, CuljBlack dyeITiO2, CuIIBlack!N7191TiO2 and CuI1N7191BlackiTi02. I-V characteristics data of Open Circuit Voltage Voc, Short-circuit current Ise and the Fill Factor FF, were determined and UV-VIS-NIR spectrometer data were obtained for the each cell configuration and dyes,dye mixtures that used. In this work, maximum power conversion efficiency of 4.98 % was obtained for solar cell with the configuration of CuI1N7191BlackiTiO2 by coupling of two metal centered dyes on TiO2 electrodes. The enhancement of photo-performances of the cell was explained by acceleration of an extra electron flow toward the TiO2 electrode. But it was observed that the configuration that having CuIlBlackIN719ITiO2 shows the low photo-performance than the cell configuration of CuIIN7191B1ackiTiO1
Development of Bio Active Herbal Jelly from Cyclea peltata (Kahipittan) Leaves
(Uva Wellassa University of Sri Lanka, 2012) Erangee, K.W.M.
Cyclea peltata is a native herbal plant which belongs to the family Menispermaceae. The C.peltata leave extraction obtained with the aid of water, transforms into semi solid structure as in jelly. This plant is also known to have possessed high medicinal value. Therefore, the gelling ability & medicinal value found in the Kahipittan leaves can be used to produce therapeutic food. To screen the bio activity in terms of anti microbial activity against Staphylococcus aureus, Escherichia coli and fungi Candida albicans were evaluated for three concentrations (0.1g/m1,0.5g/m1,1g/m1) of leaf extractions. For the sensory evaluation four workable solutions were prepared by changing the leave extraction & sugar content. Constant amount of Sodium Meta BiSulfide, permitted amount of colorings and flavors in powder form, 2% of pectin by final volume were added to each sample separately. Sensory attributes such as taste, aroma, flavor, color, appearance, and overall acceptability were evaluated using five point hedonic scale with thirty untrained panelist. Collected data were statistically analyzed using Friedman test with the confidence level of 95% using MINITAB statistical software. Microbiological analysis & shelf life analysis were performed for the selected best sample from the sensory evaluation under the refrigerated condition & room temperature condition separately. Parameters such as pH level and Total Soluble Solids were measured for the selected best sample throughout the storage under both refrigerated and normal room temperature conditions. The leaves soaked in water under the normal room temperature conditions produced the best extraction with a high gelling property. Any inhibition zone was not observed for all the microbial strains. Therefore, antimicrobial activities of C.peltata leaf extracts against all tested microbes were shown negative. According to the results obtained from the sensory evaluation, Sample "B" has scored the highest values for all sensory parameters Therefore, sample B can be recommended as the best formulation which could be improved as a commercial therapeutic jelly especially for gastritis patients. pH of the final product 3.9 and TSS 18° .Product shelf life under refrigerated storage with temperature at 4 0± 1 °C was 7 days . Microbial quality was within the acceptable limit.
Screening of Wood-Decaying Fungi for Antibacterial Activity Against Antibiotic Resistant Bacteria
(Uva Wellassa University of Sri Lanka, 2012) Dunuthilake, D.G.T.
Over the last decade it has become clear that antimicrobial drugs are losing their effectiveness the due to the evolution of pathogen resistance. Therefore, there is a critical need to search new chemical compounds that can be successfully replaced as alternatives for the antibiotics in present market. Natural products are the fundamental sources of new chemical components in the pharmaceutical industry as well as auruvedic medicine. The chemical compounds derived from the natural products are less toxic and more effective than the artificial ones. Hence, the investigation of natural products that have antibiotic properties is a promising way of receiving less toxic and effective antibiotics for the consumers. Researchers are largely deal with the medicinal plants for the investigation of new drugs. But most of them are neglecting the other natural recourses such as fungus that are having great medicinal values. Hence, the aim of this review is to explore locally available fungus varieties which are having the antibacterial properties against the highly resistant bacteria. Eight species of wood rot macrofungi were randomly collected and identified as Pleurotus pulmonarius, Pleurotus ostreatus, Tremets versicolour, Polyporus arcularius, Pluteus cervinus, Schizophyllum commune, Auricularia polytricha by using their characteristics of fruiting bodies. One fungus variety was not identify up to generic level. Ethanolic extractions of all the fungus varieties are tested against Escharichia coli, Psudomonas auriginosa and Streptococcus aurius by using disk diffusion method. It was followed by evaluation of the minimum inhibitory concentration (MIC).Ethanolic extracts of Pleurotus pulmonarius, Polyporus arcularius, Pleurotus ostreatus and Auricularia polytricha showed inhibition against all three test microorganisms. Tremets versicolour was found to be only active against Staphylococcus aureus and Psudomonas auriginosa while Schizophyllum commune only active against Escharichia coli and Streptococcus aurius. The poorest antimicrobial activity was recorded from the ethanolic extracts of Polyporus arcularius and Pleurotus ostreatus. Minimum MIC value was 8mg/m1 for tested bacteria.
The Development of Internal Sensory Panel to Assess the Sensory Qualities of Processed Meat Products
(Uva Wellassa University of Sri Lanka, 2012) Rathnayake, R.M.L.K.H.
In the food industry sensory evaluation has become a standard tool used in the development of new products and the checking the quality of the existing products. Unless the food products meet the desired standards of taste, flavor, texture, etc., the consumer will not accept the product's. Before the product goes in to the market from the industry, product's sensory quality must be checked with the help of sensory evaluators. Establishment, training and performance evaluation of sensory panel is the main objective of the study. The testing instrument for sensory analysis is the panel of human judges who have been recruited and trained to carry out specific tasks of sensory evaluation. Recruiting panelists, training them, monitoring their performance, providing leadership and motivation are the basic steps of establishing sensory panel. Recruitment of the panel was done in 3 steps. First pre screening was done by distributing a. questionnaire among all possible members in the industry. Date was evaluated using maximum score method. Second screening was done in three steps, Meat type identification test; Minced Chicken, Beef, Mutton, Pork, and fish were mixed with minimum amounts of salt. I Og balls were steam cooked and stored at -22°C for 42 hours. Five samples were served in five plates for the potential panelists. Taste type identification test; Chicken samples were made with 0.5% salt, 3% vinegar, 0.2% spice. Potential panelists were asked to identify the taste type. Different threshold level test; Chicken meat samples with each taste (salt, spice, sour) with different intensities were given to potential members. Three samples from each taste will be given to potential panelists and ask them to rank according to low, medium, high levels. 15 panelists were selected by sorting the success ratio. Training and performance evaluation was done for the selected panelists by giving two sets of three samples including one reference sample (company standard sample) with changes in salt level and spice level. Data were analyzed using Kruskal-wallis test test. A triangle test was done with meatball samples having one with 1.5% vinegar. Results of the statistical analysis proved that there is no significant different between panelists and their judgment can make significant different in the test statistics.
Phytoxicity Effect of Three Invasive Plant Species: Mimosa pigra, Parthenium hysterophorus, Ulex europaeus
(Uva Wellassa University of Sri Lanka, 2012) Prasangani, W.D.
Invasive plants are the plants that have an ability to thrive and spread aggressively outside its natural range. They adversely affect to the habitats, they invade economically and environmentally and they have an ability to inhibit the growth of other plant species by means of phytotoxicity. Phytotoxicity effect of invasive plant can be used to produce synthetic herbicides. In this study trial to screen the invasive plant for their phyto toxicity effect. Parthenium hysterophorus, Mimosa pigra and Ulex europaeus are used for the experiment which is spread aggressively in Sri Lanka by harming to other useful plants. For this study water extracts of fresh flower & dry leaves of Parthenium hysterophorus, Mimosa pigra and Ulex europaeus were obtained and the experiment was conducted with three factor factorial designs. Resulted water extracts were tested for phyto toxic activity against germinating and growing green gram (Vigna radiata) seed in five different concentrations including stock solution of the extraction for one week. Germination of the seeds was observed after 24 hours. The highest germination reduction was recorded in 50% concentration of Parthenium hysterophorus dry leaves. Both fresh flowers and dry leaves extraction of Ulex europaeus were not highly affect to the germination rate of the green gram seed. Fresh flower of Mimosa pigra was not highly affect to the germination rate of the green gram seed. Considerable decrement was shown in most of the test concentrations during one week exposure time and the results obtained show a gradual increment in phytotoxicity ability along with the concentration. According to the ANOVA there was a significant interaction effect of concentration, plant species, and plant part to the germination of green gram seeds (p < 0.05). Parthenium hysterophorus dry leaves water extract was more effective even at the lower concentrations compared to other test water extracts and can be developed as a weedicide. Mimosa pigra was shown considerable amount of toxicity especially in fresh flower extraction. Ulex europaeus was shown less amount of phyto toxicity compare with others. Ulex europaeus fresh flowers were not shown any phyto toxic effects.
Establishment of Maximum Storage Time for Uht Standardized Milk in Intermediate Storage Tank by Considering Influenced Factors
(Uva Wellassa University of Sri Lanka, 2012) Perera, P.S.P.
The aim of this study was to establish maximum storage time for an intermediate storage tank by considering influenced factors which is used to store UHT standardized milk in case of breakdown. The study was carried out in 2 parts. In the first part, the quality of raw materials, line cleanliness and temperature of standardized milk in intermediate storage were investigated for 15 batch samplesas influenced factors for storage timeusing Total Plate Count (TPC), bacterial spores, yeast and molds. The obtained results were compared with standard norms (Nestle Local Norms). Temperature of standardized milk was considered as constant. In second part, to establish maximum storage time, 15 batchsamples of standardized milk were investigated using pH, conductivity and TPC initially, after 12 hours, after 24 hours, 36 hours, 48 hours and 72 hours. According to the comparison with standard norms it showed that the raw materials were microbiologically accepted for all 15 batch samples. The results from water analysis after Clean in Place (CIP) showed that there were no microbial contaminations after CIP in interior surfaces of the lines. The average pH changedeviated from recommended pH range (6.85 — 7.20) after 24 hours according to the 95% confidence interval level. For 36 hours, 95% CI level was (6.84, 6.93). Similarly, the average TPCdeviated from recommended value (105 CFU/g) after 24 hours. According to the results of 1 sample t test the average TPC in intermediate storage tankat 36 hours was greater than or equal to 105 CFU/g. The average conductivity of standardized milk at 24 hours was 1.0 — 1.5 µS/cm suggesting a recommended conductivity range for standardized milk stored in intermediate storage tank. Statistical analysis of data illustrated that maximum storage time for intermediate storage was 24 hours if the temperature maintained at 8°C with quality raw materials, and line cleanliness.
Development of Modified Fenton’s Reactor Using Iron Pyrite
(Uva Wellassa University of Sri Lanka, 2012) Samaranayaka, P.N.
Disinfectants such as chlorine are used in drinking water treatment to protect the public health from pathogenic microorganisms. However, disinfectants also react with non harmful, naturaly occuring organic substances in the water and form by-products, such as trihalomethanes. Total trihalomethanes (TTHMs) include four compounds: chloroform, bromodichloromethane, dibromochloromethane and bromoform. TTHMs are carcinogenic and have been found to cause adverse pregnancy outcomes. Therefore, objective of the research is to find a feasible and effective method to treat the THM in the treated water and thereby to make it possible for developing countries to use already installed water treatment plants in the future too, without going for the costly methods. The research has shown that THM concentrations can be minimized by using higher paricle sizes and mass of Iron Pyrite which was obtained from the Bogala. The study designed that model for a Fenton Reactor which is low cost and accessible to even poor people.
Conversion of Eppawala Apatite into Superphosphate Using Hydrochloric Acid
(Uva Wellassa University of Sri Lanka, 2012) Priyadarshana, W.P.N.
Reaction of Eppawela apatite with HC1 has been investigated in an attempt to convert rock phosphate to phosphorus enriched manure using a simple & low cost method. Although direct reaction of apatite with HC1 lead to a highly hygroscopic product, physical condition of this material could be improved by the treatment with ammonia. Apatite reaction with 12% HC1 followed by PH adjustment using an alkali, leads to the precipitation of dicalcium phosphate (CaHPO4), which could readily be used as a P-fertilizer. Use of ammonia & ammonium salts has an added extra advantage in that the product contains nitrogen in addition to phosphorus. And also the addition of KCl to the mixture ensured availability of K in required proportions. Since the cost of this product depends mainly on the cost of HC1, partial combination with Hydrochloric acid recognized as a potentially useful and economical method.
Development of a Colorimeter for the Field Estimation of Fluoride in Drinking Water
(Uva Wellassa University of Sri Lanka, 2012) Kumari, W.G.N.D.
The name "colorimeter" is given to any instrument used for the determination or specification of colors. One type of colorimeter is an instrument used to find the concentration of a substance in solution, based on the intensity of color of the solution. If the solution to be tested is colorless, a reagent is added that reacts with the substance, producing a color. This type of colorimeter has a wide range of applications, including laboratory research, environmental analysis of water quality, analysis of soil components, monitoring of hemoglobin content in the blood and analysis of chemicals used in various industrial settings. Presence of excess fluoride in drinking water causes various diseases that are collectively referred to as fluorosis. Fluorosis is endemic at least in 25 countries. The total number of people affected due to fluoride estimated is tens of millions. The major source of fluoride is lithogenic. Fluoride enters to the human body mainly through water. A minimum amount of fluoride is required in drinking water to prevent tooth decay. According to the WHO guidelines, the permissible limit of fluoride in drinking water is 1.5 mg/L. However, a regular in take of water containing excess F— causes many chronic diseases. In this project a novel colorimeter is designed to determine fluoride concentration in water. The unit has alarming signals to alert people when the levels far exceed WHO recommendations. The colorimeter works according to Beer-Lambert Law of absorption. . It is used in conjunction with the SPADNS method, which shows a color change in the visible region on addition of water containing fluoride to a reagent solution. That color region was identified by web cam and read the color intensity.
Development of Spiced Butter Using Pepper(Piper nigrum), Cinnamon (Cinnamomum verum), Ginger(Zingiber officinale) and Garlic(Allium sativum) and Determination of Shelf Life
(Uva Wellassa University of Sri Lanka, 2012) Sheriff, M.A.M.
The use of spices in butter as a flavor enhancer has immense potential in value addition health wise as well as commercially. Butter is essentially the fat of the milk made by agitation or "churning", where the fat content should be not less than 80% and the moisture content should not exceed 16%. It is usually made from sweet cream and is salted. However, it also can be made from acidulated or bacteriologyically soured cream. Butter becomes rancid due to atmospheric oxygen, light, heat, water, metals, enzymes and microorganisms. Rancidity is the development of any off or disagreeable flavors in fat. Butter was produced by churning and working fresh pasteurized cream without the use of preservatives. Spiced butters were made by mixing pepper powder, garlic paste, ginger paste and cinnamon powder in salted butter. Sensory evaluations are carried out to identify the best dosages of spices in butter, to identify the best type of spice preferred in butter and to compare a month old product for significant differences with a fresh product. Shelf life evaluation for a month was carried out by observing the microbiological characteristics where all the butters showed counts under the maximum allowable counts throughout the month and Free Fatty Acid content behavior of the butter while keeping under refrigerated condition. 2.00% pepper treated butter is the most preferred spice butter. The free fatty acid values for the pepper, garlic and cinnamon butter did not exceed the threshold level whereas the ginger butter exceeded it at the latter part of the month.

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