International Conference on Applied and Pure Sciences (ICAPS)
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Item Evaluating the efficacy of cinnamon oil-chitosan microcapsules in inhibiting the growth of Aspergillus spp. in stored rice: A study on antifungal properties and storage stability(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Dewduni, E. A. C.; Wickramarachchi, S. R.Understanding and controlling the growth of aflatoxigenic fungi is of paramount importance to ensure food safety. Aspergillus spp. are common storage fungi, which is responsible for producing aflatoxins in stored grains posing significant health risks. Cinnamon leaf oil (CNO) has gained attention as an antifungal agent due to its low toxicity to mammals, high effectiveness, and wide availability. However, the direct application of CNO presents challenges such as volatilization, degradation, of active compounds, and imparting unpleasant taste and odor to food products. Encapsulation is an effective technique to overcome these limitations and achieve controlled release thus increasing the bioavailability of the active compounds. In this study, a comprehensive investigation was conducted to assess the in vitro growth dynamics of colonies and spores of Aspergillus spp. (A. flavus, A. niger, and A. parasiticus) over a three- month period after treating with cinnamon leaf oil loaded chitosan microcapsules (CNO-CS-MCs). Microcapsules (MCs) containing cinnamon leaf oil were prepared by ionotropic gelation technique and crosslinking chitosan with sodium tripolyphosphate (STPP 1%). Previous studies have shown that the minimum lethal dose (MLD) of CNO-CS-MCs against Aspergillus spp. for spread method was 15 mg. Rice grains (BG-11-11) were packeted in polybags and treated (spread on rice) with the MLD of CNO-CS-MCs. The growth of Aspergillus spp. on treated rice was monitored monthly for 03 months by growing the fungal extracts of treated rice on potato dextrose agar (PDA) medium. Subsequent spore quantification was carried out using a hemocytometer. The results demonstrated a reduction of the fungal colony count and spore density throughout the three-month duration. Notably, the lowest mean colony count of 5.33 CFU mL-1(SD = 1.15 CFU mL-1) was observed in the third month, suggesting a significant reduction in fungal colonies after treating with CNO-CSMCs. Additionally, the lowest average spore density of 1.26 × 10-4 spores mL-1 was observed in the third month, suggesting a significant reduction in fungal spores after treatment. These findings emphasize the promising potential of CNO-CS-MCs as a natural fungicide to control the growth of aflatoxigenic fungi on stored rice, enhancing food safety and quality during their storage.Item Growth patterns of Aspergillus sp. in stored rice during the post-harvest storage and their in-vivo growth control by cinnamon oil-chitosan microcapsules(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Rajapaksha, R. P. S. P.; Kumarathunga, P. G. J. D.; Wickramarachchi, P. A. S. R.Rice (Oryzae sativa L.) is the most important staple food crop in Sri Lanka. Inadequate storage conditions for rice can result in fungal infestation, leading to the presence of micotoxin that pose significant health risks to humans. A common storage fungus, Aspergillus sp. is responsible for producing Aflatoxins in stored grains. The use of cinnamon leaf oil (CNO) as an antifungal agent has garnered attention due to its low toxicity to mammals, high effectiveness, and wide availability. However, the direct application of CNO presents challenges such as volatilization, degradation of active compounds, and imparting unpleasant taste and odor to food products. To overcome these limitations and achieve controlled release, microencapsulation is an effective technique. Understanding and controlling the growth of aflatoxigenic fungi, specifically Aspergillus sp. on stored rice is of paramount importance to ensure food safety. In this study, a comprehensive investigation was conducted to assess the in-vivo growth dynamics of Aspergillus sp. colonies over a six-month period during the post-harvest storage. The rice samples were carefully stored in separate poly bags and rice packets to monitor any variations in fungal colonization. Microcapsules (MCs) containing cinnamon leaf oil were prepared by inotropic gelation of chitosan crosslinking with sodium tripolyphosphate (STPP 1%). Monthly observations of Aspergillus sp. in rice were performed by growing in potato dextrose agar (PDA) media and subsequent spore quantification was carried out using a haemocytometer. The results demonstrated that the spore counts exhibited slight variations throughout the six-month duration. Notably, the highest spore count of 3.02 x 107 mL-1 was observed in the sixth month, suggesting a potential accumulation of viable spores during prolonged storage. To investigate the efficacy of growth control measures, rice grains were inoculated with the spores of Aspergillus sp. and assessed the minimum inhibitory dose (MID) of cinnamon oil loaded chitosan microcapsules (CNO-CS-MCs). Remarkably, the Aspergillus sp. fungus exhibited growth when exposed to 1 - 5 mg of cinnamon oil within the microcapsules, indicating their role in facilitating fungal proliferation. However, a noticeable inhibition of fungal growth was observed when the oil dose in MCs was increased to 7.5 mg. And free CNO mixed rice grains showed 100 % growth inhibition of Aspergillus sp. at 2 mg of oil (MID). Upon further incubation in PDA media, fungal growth was detected in the 7.5-12.5 mg CNO range. And treatments with 15 mg and higher doses exhibited no fungal growth after incubation in PDA media. Therefore, the minimum lethal dose (MLD) of CNO-loaded chitosan microcapsules against Aspergillus sp. was determined to be 15 mg. These findings emphasize the promising potential of CNO-CS microcapsules as a mean to control the growth of aflatoxigenic fungi on stored rice