Browsing by Author "Pavalakumar, Dayani"

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    An analysis of regional variations in the physicochemical properties of Cocos nucifera L. var. nana across Sri Lanka
    (2024) Pavalakumar, Dayani; Undugoda, Lanka Jeewanie Samarakoon; Thambugala, Kasun Madhusanka; Manage, Pathmalal Marakkale; Ruwani, Nilushi Nugara; Kannangara, Sagarika Dilpushpi; Rajapaksha, Suranga M.
    This study explores the intriguing regional disparities in the characteristics of green dwarf tender coconut water (Cocos nucifera L. var. nana) in Sri Lanka. Physicochemical parameters of coconut water subjected to a comprehensive analysis following standard AOAC methods. The prevalent sugar types in the samples were identifed as fructose and glucose, with a minute amount of sucrose using High-Performance Liquid Chromatography (HPLC). Notably, regional diferences in sugar profles were observed during the analysis. Kurunegala samples exhibited signifcantly higher levels of total soluble solids (5.98±0.12°Brix), along with elevated total sugar (70.13±5.06 mg mL−1), total reducing sugar (68.53±5.57 mg mL−1), glucose (39.65±6.10 mg mL−1), and fructose (37.65±7.12 mg mL−1), while Colombo samples demonstrated the least values. Regarding pH values, Colombo samples exhibited a signifcantly lower value (4.87±0.10). Furthermore, a significant quantity of macro minerals such as calcium, sodium, potassium, and magnesium, along with trace minerals like iron and zinc, were identifed. Fourier-transform infrared spectroscopy analysis indicated the presence of functional groups from simple sugars and phenolic compounds as major chemical bonds for all regions. Principal Component Analysis was performed considering the Electronic Nose (E-nose) data, revealing distinctive volatile profle clusters for Kurunegala and Colombo samples. Moreover, sensory evaluations confrmed Kurunegala as the most preferred, while Colombo was ranked as the least preferred in terms of organoleptic characteristics. These fndings underscore the critical importance of regional variations in the nutritional content and sensory attributes of coconut water, which play a pivotal role in infuencing customer preferences.
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    Evaluating the Probiotic Profile, Antioxidant Properties, and Safety of Indigenous Lactobacillus spp. Inhabiting Fermented Green Tender Coconut Water
    (2024) Pavalakumar, Dayani; Undugoda, Lanka Jeewanie Samarakoon; Gunathunga, Chathuri Jayamalie; Manage, Pathmalal Marakkale; Ruwani, Nilushi Nugara; Kannangara, Sagarika Dilpushpi; Lankasena, Bentotage Nalaka Samantha
    This study isolated and characterized four indigenous lactic acid bacterial strains from naturally fermented green tender coco-nut water: Lactiplantibacillus plantarum CWJ3, Lacticaseibacillus casei CWM15, Lacticaseibacillus paracasei CWKu14, and Lacticaseibacillus rhamnosus CWKu-12. Notably, among the isolates, Lact. plantarum CWJ3 showed exceptional acid tolerance, with the highest survival rate of 37.34% at pH 2.0 after 1 h, indicating its higher resistance against acidic gastric conditions. However, all strains exhibited robust resistance to bile salts, phenols, and NaCl, with survival rates exceeding 80% at given concentrations. Their optimal growth at 37 °C and survival at 20 °C and 45 °C underscored adaptability to diverse environmental conditions. Additionally, all strains showed sustainable survival rates in artifcial saliva and simulated gastrointestinal juices, with Lact. plantarum CWJ3 exhibiting signifcantly higher survival rate (70.66%) in simulated gastric juice compared to other strains. Adherence properties were particularly noteworthy, especially in Lact. rhamnosus CWKu-12, which demonstrated the highest hydrophobicity, coaggregation with pathogens and autoaggregation, among the strains. The production of exopolysaccharides, particularly by Lact. plantarum CWJ3, enhanced their potential for gut colonization and bioflm formation. Various in vitro antioxidative assays using spectrophotometric methods revealed the signifcant activity of Lact. plantarum CWJ3, while antimicrobial testing highlighted its efcacy against selected foodborne pathogens. Safety assessments confrmed the absence of biogenic amine production, hemolytic, DNase, and gelatinase activities, as well as the ability to hydrolase the bile salt. Furthermore, these non-dairy probiotics exhibited characteristics comparable to dairy derived probiotics, demonstrating their potential suitability in developing novel probiotic-rich foods and functional products.
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    The mycoremediation potential of phyllosphere fungi in urban ornamental plants in Sri Lanka with mathematical models for PAH degradation
    (2024) Dharmasiri, Nadeema; Kannangara, Sagarika; Undugoda, Lanka; Munasinghe, Jayantha; Madushika, Ruvini; Thambugala, Kasun M.; Gunathunga, Chathuri; Pavalakumar, Dayani
    Currently, phylloremediation has emerged as a highly effective method for eliminating air pollutants, particularly polyaromatic hydrocarbons (PAHs). When PAHs accumulate on the phyllosphere, they significantly impact the fungal communities residing on leaf surfaces. This study aimed to investigate how pollution distribution patterns affect the diversity and PAHdegrading abilities of phyllosphere fungi, alongside identifying suitable mathematical models for PAH degradation. Leaf samples from two locations, Maradana and Sapugaskanda, were identified as having the highest PAH concentrations through principal component analysis. The fungal diversity in these highly contaminated regions was varied, with dominant species exhibiting greater PAH-degrading capabilities than those in less polluted areas. Thirty-five morphologically different epiphytic fungal strains were isolated on Potato Dextrose Agar (PDA) medium using the sample leaf wash. Two different fungal strains were selected as the best PAH degraders among those 35 different strains. These fungal strains were identified as Trichoderma harzianum P4M-16, and Fusarium solani P11M-46 based on ITS sequence data. Notably, these fungal species were more prevalent in highly polluted urban areas compared to less contaminated sites. High-Performance Liquid Chromatography (HPLC) analysis revealed that these two fungal species degrade PAHs more efficiently than others. Their kinetics assays demonstrated alignment with four degradation models when breaking down phenanthrene, naphthalene, pyrene, and anthracene. Scanning electron microscopy images showed that these fungi function as endophytes, extending their mycelium into the core leaf tissue layers beyond the epidermis. Gas Chromatography-Mass Spectrometry (GCMS) analysis indicated