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Undergraduate Theses

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14583/13

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2018 - 20194

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Committee Chair: search.filters.chair.Ortillo, Danilo O.SDG: search.filters.sdg.SDG 3 - Good health and well-being

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    Spontaneous formation of silver nanoparticles in humid acid-rich water of Santa Barbara, Iloilo
    Cadelina, Mary Dored Ann D. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    Humic acid (HA) - rich water of Sta. Barbara, Iloilo is successful in acting as a reducing and capping agent in the synthesis of silver nanoparticles (AgNPs). UV-Visible spectroscopy was used to determine the effect of irradiation time, varying HA and AgNO3 concentration, and electrolyte addition. Furthermore, the bactericidal efficacy of AgNPs was evaluated using broth microdilution method. Measurement of AgNPs was done using transmission electron microscopy (TEM). Lower irradiation time (10- 40 min) shows an increasing absorbance trend. However, absorbance decreased and showed bathochromic shifts when irradiated at longer times (50-60 min). AgNP formulations of 40 ppm HA with 4 mM AgNO3 and 50 ppm HA with 4 mM AgNO3 showed the highest peak intensity for varying AgNO3 and HA concentration, respectively. These results were found in both irradiated and un-irradiated samples. Aggregation occurred upon the addition of 50 mM, 100 mM, and 500 mM NaCl but was more prominent at 500 mM NaCl. Dialyzed and un-dialyzed AgNPs have bactericidal activity. However, un-dialyzed AgNP was a more effective treatment because it showed a bactericidal activity up to 1:16 dilution for both Staphylococcus aureus and Escherichia coli as compared to the dialyzed AgNPs which showed a bactericidal activity up to 1:4 for S. aureus and 1:8 for E. coli. The dialyzed AgNPs are polydispersed but were mostly small with sizes less than 10 nm based on the TEM image.
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    Antifungal activities of alginate films incorporated with lemon grass (Cymbopogon citratus) essential oil on sliced bread
    Bronzal, Lucile A. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    The accumulation of non-degradable and non-recyclable waste materials leads researches to venture on biopolymer films which have been regarded as the promising green substitutes of non-biodegradable plastic materials. However, food products can be subjected to contamination by bacteria and fungi. The addition of plant derived essential oil can control microbial contamination of foods by reducing the growth rate of target microorganisms or by inactivating microorganisms by direct or indirect contact. Incorporating antimicrobial compounds into films provides a different way to improve the safety of ready-to-eat foods. In this study, the efficiency of synthesized alginate films incorporated with lemon grass essential oil (LGEO) for antifungal activity on white bread was evaluated. Two sets of film were prepared the (1) LGEO - Ethanol incorporated films and (2) LGEO — β-cyclodextrin inclusion complex films via solution casting method. Furthermore, the FTIR analysis of the generated films was also assessed to identify the functional groups present in the film that facilitates its antifungal property. Experimental results showed that LGEO enhanced the antifungal properties in the films and significantly slowed down the propagation of fungi on white sliced bread. After two weeks of storage, all bread samples packed with various film samples showed fungal growth. It was found out that citral is the main component of essential oil which contributes to the inhibition of fungal growth. The incorporation of LGEO in the film decreased the O-H peak absorbance while the inclusion complex in the film increases the O-H peak absorbance and broad O-H peaks were also obtained.
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    Antifungal activities of lemongrass (Cymbopogon citratus) essential oil -B-cyclodextrin inclusion complex incorporated in commercial fish feeds
    Baure, Jiaren G. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2019-06)
    During the wet season in the Philippines, fish feeds can be contaminated with mycotoxins, affecting fish production. The addition of essential oil (EO) is one of the ways to prevent this, but it is prone to physical and chemical reactions. Thus, this study aims to encapsulate lemongrass essential oil (LGEO) in B-cyclodextrin (B-CD) to produce an inclusion complex (IC) that can be used as an additive in commercial tilapia feeds to prevent or minimize fungal contamination. The inclusion complex was made using the co-precipitation method and was characterized by Fourier Transform Infrared (FTIR) Spectroscopy. The spectrum was similar to that of citral, a major component of lemongrass essential oil that is responsible for inhibiting fungi. The antifungal activities of pure and encapsulated LGEO at varying concentrations against Aspergillus species were carried out by the Agar Well Diffusion assay. Results showed that A. flavus was more susceptible in LGEO and IC compared with A. fumigatus. The tested concentration of EO could inhibit both fungi. However, it would take 50% IC to effectively inhibit the growth of both fungi. The stability of the inclusion complex in commercial fish feeds was also evaluated. The feeds were stored in an area with the appropriate conditions that could promote the growth of molds, such as temperature (>27°C), moisture levels (14%), and relative humidity levels (>70%). The results showed that the encapsulated LGEO was effective in extending the shelf life of the feeds and was best observed at a concentration of 5 g kg-1 IC. The oil remained active for nine days, wherein about 10- 40% of the feeds with 5 g kg-1 IC were covered with molds. On the other hand, about 70-100% of the surface of the feeds with essential oil was contaminated with molds after nine days, which indicated that encapsulation of EO was needed to maintain its effectiveness as an antifungal agent.
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    A novel water-in-oil-in-water emulsion to encapsulate antibacterial agents
    Balcarcel, Angelica V. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2018-06)
    Encapsulating bioactive compounds can protect them from adverse conditions. This study aimed to encapsulate bioactive agents in a stable multiple emulsion system using a material that can be recovered easily from a product abundant here in the country. Results of the study revealed that the method of encapsulation used is effective in encapsulating and releasing the bioactive compound encapsulated. The antibacterial activity determination showed that encapsulated chlorhexidine is effective against both S. aureus and E. coli bacteria. Further investigation was made by encapsulating aqueous guava (Psidium guajava) extract in the same emulsion system (water-in-oil- in-water) using recovered coconut milk protein (CMP) as a gelling agent. The evaluation of the stability of the emulsions revealed that the treatment with 40% guava extract in the aqueous phase of its primary emulsion (Emulsion 3) is the most stable among the other treatments. This treatment showed the smallest droplet size range and most uniformed droplet sizes. The creaming index of this treatment also showed the lowest values after three (3) weeks of storage. On the other hand, the treatment with 60% guava extract in the aqueous phase of its primary emulsion (Emulsion 4) appeared to be the most stable against heating. However, no antibacterial activity was observed for any of the emulsion systems both S. aureus and E. coli bacteria. Additional test revealed that the bioactive compound present in the plant extract was disrupted by the sonication process