Undergraduate Theses
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Item Microwave-assisted extraction of sulfated polysaccharide (Fucoidan) from Sargassum oligocystum MontagneCaceres, Kristhia Loren Maree R. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2016-06)Algae have been a source of food and medicine for humans. It contains sulfated polysaccharides that have been used as drugs. Fucoidan, a sulfated polysaccharide, found in brown algae have received more attention in recent years due to its potential biological properties that are important in cosmetics, pharmaceuticals and health industries. Fucoidan was recovered from brown seaweed Sargassum oligocystum Montagne by microwave - assisted extraction (MAE) technology. Different conditions of extraction time (10, 15 and 20 min) at 0.150kW were evaluated and the optimal fucoidan yield was 1.255 ± 0.0068 %, obtained at 20 minutes. Using this condition, a different set of samples was subjected to hot water extraction (HWE) and the average yield was 0.9767 ± 0.0002 %. The extracts from both methods were subjected to physico-chemical tests like gelling temperature, melting temperature, FTIR analysis, total carbohydrate content and total sulfate content. Having gelling and melting temperature values of 32 "C and 91"C for MA extracts and 30 "C and 89 °C for HW extracts showed qualities of a good agar gel. The total carbohydrate contents were 75.31 ± 0.015 % and 74.06 ± 0.0113 %, for MAE and HWE, respectively. It was also observed that the sulfate content of extracted fucoidan decreased with increasing extraction time. This study shows that MAE is an efficient technology to recover fucoidan from Sargassum oligocystum Montagne compared with the conventional heating method. This method provided enhanced extraction efficiency at reduced process time.Item Photodegradation of methylene blue in aqueous media using TIO2 -based heterogeneous photocatalysts under natural lightBernido, Julidyn P. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2015-06)This study developed two heterogeneous TiO2-based photocatalysts: pure TiO2 and Fe-doped TiO2 (Fe-TiO2). Heterogeneous catalysts were prepared by coating TiO2 and Fe-TiO2 powder on glass beads. The photocatalytic activity of both heterogeneous photocatalysts were studied by photodegradation of methylene blue in aqueous solution under two pH conditions (6 and 9) and two ionic concentration conditions (0 and 38 ppt). The Fe-TiO2 powder contained minimal amount (2.245%) of Fe as expected. However, surface functionality and ultraviolet-visible (UV-Vis) profile of both TiO2 and Fe-TiO2 powder were very similar indicating that doping did not alter these properties. Between the two heterogeneous catalysts prepared, the amount of Fe-TiO2 catalyst coated on glass beads was lower compared to pure TiO2. The removal of methylene blue was significantly affected by ionic concentration which removal is higher at lower ionic concentration (0 ppt). Although it appeared that the removal of methylene blue was higher at pH 9, statistical analyses revealed that the effect was not significant. In addition, the removal of methylene blue by the two catalysts were significantly different. Heterogeneous photocatalyst based on pure TiO2 showed higher removal of methylene blue in all pH and ionic concentration. Moreover, no interactive effects between variables were observed. Lastly, the blank showed no significant difference on the removal of methylene blue with the heterogeneous photocatalysts which suggest that degradation by direct photolysis from sunlight could be the reason for this result.Item Comparison of protein quality of three seaweed species (Sargasum polycystum, Sargassum oligocystum and Ulva pertusa) from Panay and Guimaras Island, Philippines for potential use in milkfish feedArnaiz, Regina Marielle T. (Division of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2016-06)Aquafeed production is the largest expenditure in intensive aquaculture operations, contributing to about 40-60% of total costs (Yildrim et al., 2009; Akiyama et al., 1992 cited in Ali et al., 2009). This is mostly due to the ingredients being used, particularly the protein source fishmeal (Millamena, 2002). The variable and finite supple of fishmeal, however, result in high costs, prompting the search for cheaper alternative ingredients as a priority in cost reduction practices regarding the production of aquafeeds (Attala and Mikhail, 2008). Seaweeds have known nutritional values, and are naturally abundant in Philippine waters, thus their potential could be tapped to reduce costs in aquaculture and could therefore maintain the sustainability of the industry (Shields and Lupatsch, 2012; Trono, 1999). In this study, the protein quality of two brown seaweeds (Sargassum polycystum and Sargassum oligocystum) and one green seaweed (Ulva pertusa) was evaluated by determining their crude protein content, inhibitory activities against trypsin and chymotrypsin, and in vitro protein digestibility. Among the three species, the green seaweed U. pertusa has the highest crude protein content at 23.43%. The obtained crude protein content was 8.28% for S. polycystum and 9.22% for S. oligocystum. Trypsin inhibition of the seaweeds ranged from 54-57%, and chymotrypsin inhibition was from 57-64%. Total phenolic content (TPC) was highest in S. polycystum, and lowest in S. oligocystum. In vitro protein digestibility action of milkfish gut enzyme was highest in S. oligocystum (92.30 ± 2.80), followed by the observed digestibility in U. pertusa (75.01 ± 2.14), and lowest in S. polycystum (64.99 ± 8.11). Determination of Pearson's correlation (r) showed a negative correlation (r=-0.99, p=0.08) existing between the TPC and %RPD values. Based on the results, among the threes species, U. pertusa with 23.43% crude protein content and a %RPD of 75.01% has a potential for partial inclusion in aquafeeds to reduce costs.