Browsing by Author "Edirisinghe, E.M.R.K.B."

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    Analysis of Pesticide Residues in Rice Cultivated in Anuradhapura District Using Multi-Residue QuEChERS Method with LC-MS/MS Detection
    (Uva Wellassa University of Sri Lanka, 2019-02) Jayasekara, G.H.S.D.; Liyanaarachchi, G.V.V.; Mubarak, M.N.A.; Edirisinghe, E.M.R.K.B.
    Rice is the staple food of Sri Lanka and where different types of pesticides are used for paddy cultivation. Presence of agrochemical residues in human body has been identified as one of the major reasons for the chronic kidney disease with unknown aetiology (CKDu) identifying Anuradhapura as a district with a high level of risk. The aim of this study was to evaluate the level of pesticide residues available in rice in Anuradhapura district. Total of 60 rice samples were analyzed for 29 pesticide residues. The extraction and clean-up were performed using a validated modified QuEChERS method with liquid chromatography - tandem mass spectrometry (LC-MS/MS) detection. Twelve samples showed contamination with Pretilachlor exceeding the default European Union (EU) maximum residue levels (MRL) with significant contamination (p = 0.005) were observed in Mihinthale. Among the 29 pesticide residues studied, BPMC was the mostly detected pesticide residue which was in the range of 0.003-0.01 mg kg-1. Further, significant contamination of Chlorpyrifos (p = 0.003), which was a banned pesticide, was detected in Ipalogama, and Diazinon (p = 0.001) was detected in Thalawa. However, the average residual levels were below the national and the Codex MRL's. Contamination from Carbosulfan exceeding the EU MRL levels were seen in two samples while Tebuconazole was the sole fungicide detected out of the 60 samples investigated however with values less than the MRL’s. The highest number of contaminated samples was detected in the Nuwaragam Palatha East and Nochchiyagama while the least contamination from pesticide residues was observed in Galenbidunuwewa, Kahatagasdegiliya and Horowpothana. As a whole, 43% of the total samples either exceeded or equaled the EU MRL’s for rice. Hence, the findings highlight the immediate requirement of a regular monitoring system for pesticide residues in rice and a strong national policy on safer use of pesticides in paddy cultivation in Sri Lanka.
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    Assessment of Oxidative Stability and Fatty Acid Composition of Gamma Irradiated Edible Oils
    (Uva Wellassa University of Sri Lanka, 2019) Ekanayake, E.M.R.M.; Edirisinghe, E.M.R.K.B.
    The safety and shelf-life of food products can be enhanced by modern food processing techniques such as irradiation. This study was carried out to investigate effects of gamma irradiation on fatty acid composition and oxidative stability of nine edible oils including Coconut oil, Corn oil, Sunflower oil, Soybean oil, Vegetable oil, Cod liver oil, Commercial fish oil, Tuna oil and Thilapia oil. The irradiation was applied at 15, 30, 45, 60 and 75 kGy levels using Cobalt-60 radiation source at Sri Lanka Gamma Center. The oxidative rancidity of oil samples was tested by Peroxide value (PV) and Thiobarbituric acid value (TBA) tests. The fatty acid profiles were determined by capillary column gas chromatography with flame ionization detector. The lowest and the highest PV were shown in Coconut oil (0 meq/kg) and Vegetable oil (10.54 meq/kg). All the samples showed their highest PV at 15 kGy dose whiles the lowest PV at 75 kGy dose. The TBA values of fish oils were significantly (p < 0.05) higher than plant and vegetable oils. The highest TBA value (270.37 nmol/g) was shown in Thilapia oil irradiated at 15 kGy. The lowest TBA value (2.41 nmol/g) was reported in control sample of Coconut oil. The fatty acid profiles of treated oils showed substantial stability during irradiation. Oleic acid (C18:1 ω-9) was the most abundant fatty acid in vegetable oils (43.78%) followed by in Tuna oil (24.84%) and Thilapia oil (30.79%). Linoleic acid (C18:2 ω-6) was the highest abundant fatty acid in Corn oil (50.00%), Sunflower oil (48.75%) and Soybean oil (52.79%). Lauric acid (C12:0) was the highest abundant fatty acid in Coconut oil (43.55%). Higher amount of Docosahexaenoic acid (C22:6 ω-3) was recorded in Tuna oil (18.89%), fish oil (10.06%) and Cod liver oil (10.22%). However, gamma irradiation at 15-75 kGy doses did not show any significant (p<0.05) effect on the fatty acid composition of any edible oil where they showed a good stability during irradiation processing.
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    Assessment of the Omega-3 Fatty Acids Composition and Heavy Metals Content in Fish Oils in Sri Lankan Marine Fishes
    (Uva Wellassa University of Sri Lanka, 2021) Jayakody, J.A.K.S.; Senevirathne, S.A.; Senarathna, L.; Edirisinghe, E.M.R.K.B.
    The consumption of fish oil provides numerous speculated health benefits due to the presence of long chain omega-3 polyunsaturated fatty acids (PUFA). These health benefits may be challenged by the presence of heavy metals in fish oil. The objective of the present study was to compare the health benefits of omega-3 fatty acids and assess the risk of some heavy metals in fish oil extracted from marine fish. Sixteen species of fish were collected (n=3) from the Trincomalee fish market and fish oils were extracted using standard Bligh and Dyer method. Fatty acid composition of extracted fish oils were quantitatively determined by Gas Chromatography - Mass Spectrometry (GC-MS). The Arsenic (As), Cadmium (Cd) and Lead (Pb) contents were determined by using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS). The amount of fat present in fish varieties was varied over a wide range of 0.619% (Acanthocybium commersoni) to 8.626% (Carangoides fulvoguttatus). Among these species, the omega-3 content ranged from 7.814% - 31.818% of total fatty acids and the highest of omega-3 content was showed in Hemiramphus sp. (9.20 mg/100 g) and lowest level was reported in Auxis thazard (0.036 mg/100 g). In all species studied, Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) are the major omega-3 fatty acids and amounts of EPA and DHA have been exceeded 70% of the total omega-3 PUFAs. The content of As in extracted fish oils were ranged from 2.4353-18.3975 mg/kg in Nemapteryx caelata and Elagatis bipinnulata while Cd content were varied from 0.0262 - 1.2305 mg/kg in Scomberomorus commersoni and Nemapteryx caelata respectively. Platax sp. reported the lowest Pb content (0.467 mg/kg) while Acanthocybium commersoni reported the highest (2.282 mg/kg). Some of the fish oil samples had exceeded recommended human daily intake values of heavy metals, thus benefite of omega-3 fatty acids is challenged. Keywords: Fish oil; Omega-3 fatty acids; Heavy metals; GC-MS; ICP-MS
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    Development of Omega-3 Fish Oil Fortified Functional Stirred Yoghurt by Incorporating Annona muricata (Soursop)
    (Uva Wellassa University of Sri Lanka, 2021) Shanuke, D.S.; Marapana, R.A.U.J.; Hettiarachchi, S.; Edirisinghe, E.M.R.K.B.
    Fish oil is an ideal source of Omega-3 polyunsaturated fatty acids (PUFAs) which lower the risk of numerous non communicable diseases. Consumption of fish oil is not popular in Sri Lankan community. This study aimed to develop a fish oil fortified functional stirred fruit yoghurt to deliver Omega-3 PUFAs and to evaluate the effect of fortifying yoghurt with fish oil on sensory, physicochemical properties and oxidative qualities. Initial sensory analysis for fish oil fortified yoghurt was performed by adding 5% (w/w) three different fruit juices including soursop, mango and pineapple by thirty untrained panelists. Fish oil fortified soursop added stirred yoghurt showed the highest score for overall acceptability as 7.32 ± 0.85 (p < 0.05). Results of second sensory analysis have shown that addition of soursop up to 15% (w/w) level was considerably masked the fishy odor and flavor of fish oil (1% w/w) fortified yoghurt. Fish oil emulsion was prepared with guar gum, gelatin and glycerol using Nano emulsion technique. Physicochemical and oxidative qualities were compared among fish oil emulsion added soursop yoghurt (FOESY), fish oil fortified plain yoghurt (FOPY) and bulk fish oil fortified soursop yoghurt (BFOSY) during the storage of 21 days at 4°C. Peroxide values (PV) were analyzed to determine oxidative stability. Syneresis values increased in all yoghurt samples during storage. The highest syneresis value of 45.18 ± 1.98 was recorded by FOPY on day 14. BFOSY and FOESY showed significantly lower syneresis (p < 0.05). pH values gradually decreased and titrable acidity values as lactic acid increased in all treatments during storage.The pH values of both FOESY and BFOSY was 4.5± 0.01 at day 14. FOESY recorded the lowest (p < 0.05) PV (4.64 ± 0.12 mEq O2 kg-1) at day 21 compared to BFOSY and FOPY. The Escherichia coli and coliform counts were complied with the requirements of SLS but yeast and molds counts had exceeded SLS limits after 14 days. This study demonstrated the potential of producing fish oil emulsion fortified functional yoghurt with acceptable level of sensory characteristics, physicochemical properties and oxidative stability by incorporating soursop juice. Keywords: Omega-3; Fortification; Fish oil; Yoghurt; Soursop
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    Effect of Gamma Irradiation on Histamine Content of Yellowfin Tuna (Thunnus albacares) Fish Muscle
    (Uva Wellassa University of Sri Lanka, 2018) Surendra, I.H.W.; Edirisinghe, E.M.R.K.B.; Rathnayake, R.M.N.P.
    Food irradiation is a process that has proven to be successful, due to its high effectiveness in inactivating pathogens without deteriorating product quality. Histamine is a causative agent for scombroid foodborne poisoning which effects on the quality of fish products. Therefore present study was conducted to evaluate the effect of gamma irradiation on histamine content in Yellowfin tuna fish fillets. Fish flesh was treated by Co-60 source at doses of 1, 3, 5, 7 and 10 kGy. Initial determinations were made just after irradiation and second determinations were made after storing control and irradiated samples for 24 hours at room temperature (30 °C). The concentration of histamine was detected by using High Performance Liquid Chromatography (HPLC) method. Total bacterial count (TPC) was performed according to the ISO 4833:2003 standard. The highest increment was detected in control sample after 24 hours of storage period and rate of increment of histamine is 9.97%. After 24 hours of storage, irradiated samples showed 2.40, 2.00, 3.00, 8.69 and 7.31% of increment in histamine at 1, 3, 5, 7 and 10 kGy irradiations respectively. However, no any significant difference found between any treatments. As revealed by results of TPC, highest amounts were found in control samples (3.03 x 105 cfu/g initially and 1.44 x 108 cfu/g after 24 hours storage period). In spite of increment in bacterial count in 1 kGy irradiated sample (7.4 x 105 cfu/g), all other samples were not exceeded the maximum level of acceptance in bacterial count (5 x 105 cfu/g) either after 24 hours of storage. The TPC results showed significant reduction after irradiation and within the storage time respect to the control. The results revealed that the low dose (3 kGy) irradiation can implement for the better safety of Yellowfin tuna fish fillets according to the changes in the histamine content and bacterial count.
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    Variation of Antioxidant Activity of Traditional Rice Due to Gamma Irradiation
    (Uva Wellassa University of Sri Lanka, 2018) Kumar, M.P.U.; Edirisinghe, E.M.R.K.B.
    Many traditional rice varieties are very high in nutritional value and reported to have medicinal properties, but can be experienced quality degradation due to many reasons. Irradiation is one of the best technologies that can be used in food preservation very effectively. This study was carried out to investigate the effect of gamma irradiation on antioxidant properties of ten different, commonly available traditional rice varies of Sri Lanka. The varieties including Suwandel, Madathawalu, Kuruluthuda, Pachchaperumal, Kahamala, Rankahawanu, Hichchinangi, Gonabaru, Heenati and Hatadaa were collected from North central province in Sri Lanka. The verities were irradiated at 5 kGy levels using Cobalt-60 radiation sources at Sri Lanka Gamma Center of the Atomic Energy Authority of Sri Lanka. The antioxidant activities of these rice varieties were determined by using DPPH method. The free radical scavenging activities of these rice samples were compared with Ascorbic acid and BHT as standard. The highest antioxidant activity of unprocessed raw rice was reported in Hatadaa (93.3%) followed by Hichchinangi (93.2%), Madathawalu (92.5%), Kuruluthuda (92.3%), Heenati (92.0%), Gonabaru (92.0%) and Pachchaperumal (88.2%) with respect to standard BHT (93.5%) and Ascorbic (96.0%). However, Kahamala (46.0%), Suwandel (29.0%) and Rankahawanu (35.3%) showed low antioxidant activity. No significant difference of antioxidant activity was reported in irradiated rice samples. The antioxidant activity of irradiated Hatadaa (92.6%), Hichchinangi (91.7%), Kuruluthuda (92.0%), Heenati (92.0%), Gonabaru (92.6%) were still higher and no significant reduction were recorded. The study concluded that the gamma irradiation process not considerably change the antioxidant activity of Sri Lankan traditional rice varieties.