Browsing by Author "Madage, S.S.K."

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    Effect of Guar Gum and Carboxymethyl Cellulose on Heating Behavior of Coconut (Cocos nucifera) Milk
    (Uva Wellassa University of Sri Lanka, 2020) Thennakoon, T.M.N.D.; Madage, S.S.K.; Jayasinghe, M.D.; Medis, W.U.D.; Mudannayake, D.C.
    Thermal processing is used to destroy Clostridium botulinum in low acid canned foods such as coconut milk (CM) and thereby, extend the shelf life. The length of the thermal treatment is established based on the targeted thermal destruction (12D destruction) of C. botulinum. at 121.1°C in the container cold point. Typically, the addition of stabilizers into CM is performed to increase the emulsion stability and to alter the heat transfer behavior. Therefore, the main objective of this study was to investigate how the heating behavior of CM could be changed with the addition of different stabilizers. During the study, heating behavior and heat-sensitive properties of CM were studied at three different temperatures (30, 50 and 80°Ϲ) against the separate addition of Guar Gum (GG) and Carboxymethyl Cellulose (CMC), that were incorporated at levels of 0.05, 0.1 and 0.5%. Extracted fresh CM was standardized for 17% fat and homogenized at 894 g for 5 min. Homogenized samples having different levels of GG and CMC were prepared from standardized CM. Specific gravity and viscosity of prepared samples at 30, 50, and 80°Ϲ were determined using the gravimetric method and viscometer, respectively. Cold point and the length of thermal processing to achieve target thermal death time (F0) of C. botulinum (2.52 min) were determined for prepared CM in aluminum cans. It was found that the specific gravity of samples at 30-80°Ϲ was in the range of 0.9778±0.05- 1.0176±0.01 for GG and 0.9957±0.00-1.0164±0.03 for CMC and that did not significantly differ (p>0.05) and viscosity was in the range of 9.98±3.31-126.70±0.00 for GG and 9.98±3.31- 40.00±3.30 for CMC. The cold point of canned CM was found to be the center of the can which was above 3 cm from the bottom. The addition of stabilizers did not affect the cold point of canned CM. Incorporation of GG and CMC into CM had no significant effect (p>0.05) on the processing time (80.2-88.8 min. for GG and 86.8- 88.8 min. for CMC). In conclusion, the heating behavior of canned CM was not affected by the addition of GG and CMC. Keywords: Coconut Milk, F0, Cold point, Viscosity, Specific gravity
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    Identification of Potential Spoilage and Pathogenic Microorganisms Associated with Production of Thermally Processed King Coconut Water (Cocos nucifera var. aurantiaca) in Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2021) Jayasinghe, M.D.; Jayawardana, T.M.D.N.; Madage, S.S.K.; Hewajulige, I.G.N.; Halmillawewa, A.P.; Divisekera, D.M.W.D.
    Thermally processed king coconut (Cocos nucifera var. aurantiaca) water is one of the fastest growing export commodities in the food and beverage sector in Sri Lanka. Microbial safety of thermally processed king coconut water is demanded by Food and Drug Administration to ensure safe consumption. This study aimed to identify potential spoilage and pathogenic microorganisms associated with king coconut water processed in Sri Lanka. King coconut water samples were collected at pre-identified sampling points; P1-Nut water extraction, P2-Bulk collection, P3- Standardization/Acidification, P4-Pre-heating prior to hot filling and P5; Sterilization/Pasteurization in three processing facilities; F1 (semi-automated), F2 (automated) and F3 (manual), where Pasteurization (100 °C/12.5 min), UHT Sterilization (140 °C/3s) and Pasteurization (100 °C/20 min) were practiced, respectively. Serially diluted king coconut water were plated on Nutrient Agar, Potato Dextrose Agar, Eosin Methylene Blue Agar and Reasoner‟s 2A Agar, incubated at 30 ± 1 °C for 48 h, 25 ± 1 °C for 2 - 5 days, 37 ± 1 °C for 48 h and 37 ± 1° C for 48 h, respectively. Purified bacterial and fungal colonies were morphologically characterized. A total of 29 bacterial isolates and 24 fungal isolates were identified by 16S rRNA and 26S/5.8S rRNA/ITS gene amplification, respectively followed by sequencing using 27F/1492R and ITS-1/ITS-4 primers, respectively. Evolutionary relationships of identified species were predicted using MEGA 7. The study revealed that thermal resistant, facultative-anaerobic, spoilage and pathogenic bacteria (Pantoea dispersa, Bacillus siamensis, Pseudomonas stutzeri, Acinetobacter lactucae) and fungi (Candida carpophila, Pichia kudriavzevii, Debaryomyces nepalensis, Microdochium fisheri, Penicillium citrinum) were survived in the thermally processed finished product. Further, potential risk of Klebsiella pneumoniae, Enterobacter roggenkampii, Enterobacter kobei, Escherichia fergusonii, Bacillus nealsonii, Serratia rubidaea, Trichosporon asahii, Wickerhamomyces anomalus, Saccharomycetales species and Fusarium species were identified at initial processing steps (P1-P3) in studied processing facilities. In conclusion, the study revealed that the existing thermal treatments are not sufficient for the destruction of identified potential spoilage and pathogenic microorganisms associated with studied processes. Thereby, suggesting thermal process validation, while targeting identified potential harmful microorganisms with optimum time-temperature combinations to ensure product safety. Keywords: King coconut water; Spoilage and pathogenic microorganisms; Molecular identification; Thermal processing
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    Study of Accumulation of Polycyclic Aromatic Hydrocarbons (PAHs) in Smoked Fish (Thunnus albacares) Under Different Storage Conditions
    (Uva Wellassa University of Sri Lanka, 2019) Uyangoda, D.N.M.; Madage, S.S.K.; Gunasekara, M.M.N.P.; Medis, W.U.D.; Abeyrathne, E.D.N.S.; Jayawardana, J.M.D.R.
    Fish smoking is the most extensively used simplest preservation technique. Although, accumulation of carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs) from wood burning is a major problem associated with the smoked fish. Hence, this research was focused to study the penetration of PAHs in to center of the smoked fish (Thunnus albacares) and effect of accumulated PAHs content with the time under different storage conditions. Fish chunks having equal thickness were smoked using smoke of coconut husk and stored under refrigerated (4C) and frozen (-18C) conditions. PAHs content of surface and center part of stored smoked fish chunks were analyzed at predetermined time intervals by Infinity Quaternary Gradient HPLC system with FLD and UV detectors. Moisture content, water activity, pH, texture, and color of smoked fish samples were also analyzed. PAHs content (Anthracene) of the surface of the smoked fish at the beginning of storage was 190.39 µg/kg and that was declined during both refrigerated (after 6 day 130.09 µg/kg) and frozen storage (after 15 day 106.19 µg/kg). But PAHs content (Anthracene) of the center of the smoked fish at the beginning of storage was 0.00 µg/kg and that was increased during both refrigerated (after 6 day 19.88 µg/kg) and frozen storage (after 15 day 45.47 µg/kg). There were no significant changes in the moisture content (68.49±0.5%) water activity (0.967±0.007), pH (6.04±0.21) and firmness (0.909±0.162 kg) of the smoked fish during the storage (p>0.05). Therefore, results revealed that PAHs penetrate in to the center part of the smoked fish during the storage.
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    Study on the Effect of Different Levels of Heat on the Quality of Dark muscle of Yellow Fin Tuna Thunnus albacares
    (Uva Wellassa University of Sri Lanka, 2013) Jayasinghe, L.L.S.L.; Wijesundara, W.M.N.M.; Liyanage, N.P.P.; Madage, S.S.K.
    Coastal and off shore marine production in Sri Lanka has an increasing trend. According to Department of Fisheries and Aquatic Resources, a catch of 417,220 metric tons was recorded in 2012. Yellow fin Tuna (Thunnus albacares) is included in large pelagic fish catch of Sri Lanka and it composed 10% of total marine catch in 2012. Yellow fin tuna (YFT) is mainly exported as Loins, Steaks, Centre cuts, Cubes, Medallions and Saku in processed form. Currently there are 27 European Union approved fish processing factories in Sri Lanka. Considerable parts of fish are removed as by-products during processing; this includes dark muscle, fins, skin, head and viscera parts. The amount of by-products produced during fish processing is vary between 40-75% of the total weight of fish according to the way of processing (Shahidi (1994), cited in Zapata et al., 2011). Though some value addition is done to these by-products there are plenty of opportunities to add value to by-products like YFT dark muscle. Thermal preservation is one of the current techniques used in value addition. Therefore, it is very important to know the quality changes of YFT dark muscle when they undergo thermal preservation techniques. Although many studies have been conducted to determine the initial quality of this muscle, still the quality changes with the different heat treatments are not studied. Therefore, objectives of this study were to evaluate the effect of different levels of heat treatments on the physical, chemical and organoleptic properties of YFT Dark muscle (DM). Methodology DM of YFT fish processed at Ceylon Fresh Seafood Private Limited in Ja-Ela were collected and transported with gel ice at 4°C to Industrial Technology Institute (ITI) and stored in -18 °C until used for the experiment. Experiment was conducted as three stages as fresh fish quality determination, pre-trial and heat treatment study using 0.5 kg, 1.5 kg and 2 kg amounts respectively. For fresh fish quality determination, physical properties including colour (Minolta Chroma meter CR-200, Japan), texture (as firmness using GUSS fruit texture analyser, United States of America) and water holding capacity and chemical properties including moisture, ash, crude protein, crude fat, water soluble protein content, pH of 10% muscle solution and water activity (AquaLab® apparatus-Series 3 TE, USA) of fresh muscle were determined by following respective AOAC methods. Colour and texture of approximately 3×2.5×1 cm sized undisturbed muscle chunks were recorded. Sensory evaluations (acceptance test with five point hedonic scale) were conducted with seven trained panellists of sensory panel of ITI using fish chunks as pre-trials. Those chunks were marinated overnight with 2% salt, to determine the best deep frying and boiling durations. As time durations 05, 10 and 15 minute durations were selected and frying was done in coconut oil at 185 ºC while boiling was performed at 100 ºC. For the heat treatment study, fish chunks were prepared as in pre-trial and those were boiled and deep fried for five minutes. Fish chunks were canned in A-1 sized cans with2% salt solution at 121.1 ºC for ten minutes. Finally the chemical and physical properties of heat treated DM were determined. Final organoleptic quality of the heat treated DM was evaluated by nine trained panellists of ITI using acceptance test with nine point hedonic scale. Physical and chemical quality data were analysed using one way analysis of variance procedure in Minitab 16 statistical package. Sensory evaluation data were analysed using Friedman non parametric test in SPSS 22.0 statistical package. All mentioned significant differences are given at P<0.05.