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UPV Theses and Dissertations

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    Production and bioactivity characterization of protein hydrolysate from Portuguese oyster (Crassostrea angulata)
    Gomez, Honey Lyn R. (University of the Philippines Visayas, 2019-06)
    ABSTRACT It has been shown that oysters represent diversified peptides with a variety of biological importance. In the present study, the use of proteomics techniques and bioinformatics tool was carried out to predict the potential bioactivities of Portuguese oyster (Crassostrea angulata). Mascot database search have identified 8 proteins from C. angulata and 5 of which were selected for in silico analysis. Interestingly, BIOPEPUWM database analysis predicted that pepsin (pH > 2) can theoretically release highest number of peptides with biological activities, predominantly angiotensin-1 converting enzyme (ACE) and dipeptidyl peptidase (DPP-IV) inhibitory activities, followed by stem bromelain and papain. To confirm the reliability of these predictions, C. angulata proteins were assessed in vitro. Results showed that all the hydrolyzed samples possessed inhibitory effect against ACE and DPP-IV, with pepsin hydrolysate (PEH) having the strongest activity of 78.18% and 44.34%, respectively. Further fractionation of PEH revealed that fractions with low molecular weight (MW) such as <1 kDa fraction (Fl) and 1-5 kDa fraction (F2) can demonstrate higher ACE and DPP-IV inhibitory activity compared to crude PEH and >5 kDa fraction (F3), but not to a great extent. Overall, the results obtained from in vitro analyses corresponded with the in silico predictions. Findings of this study thereby suggest the applicability of in silico technique for rapid and reliable identification of bioactive peptides from food proteins and determination of suitable enzyme capable for the release of these peptides. Moreover, proteins from C. angulata can be considered as potential sources of peptides with potential pharmaceutical and nutraceutical application.
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    Influence of various photobleaching conditions on algar quality from Gracilariopsis heteroclada
    Endoma, Leonilo Jr. F. (University of the Philippines Visayas, 2016-06)
    ABSTRACT The photobleaching agar extraction technology stems from public health, environmental, economic, and issues concerning agar stability. With the hypothesis that photobleaching reduces the total inorganic sulfate content in the alkaline-treated seaweed prior to agar extraction, the influence of various photobleaching processes on agar quality was tested. The 5-hour photobleaching agar extraction process using solar irradiation (SLA) effectively increased agar gel strength (1,038.61 g cm-2) and 3,6-anhydrogalactose content (41.44%), and decreased total inorganic sulfate content (1.87%) without compromising agar yield (19.37%). The agar extracts of SIA was found superior compared to samples from other bleaching methods tested (i.e., CBA: conventional chemical-bleaching agar extraction process using using NaOCl; UVA: ultraviolet agar photobleaching extraction process; and VLA: visible light agar photobleaching extraction process) in terms of carbohydrate content (90.50%), neutral gel pH (6.93), gel rigidity (815.31 g cm'1), gel cohesion (10.95 mm), breaking strength (7.99 N), apparent viscosity (19.67 cPs), melting temperature (92.67°C), thermal hysteresis (50°C) and has the lowest syneresis index (73.00 mm). The results also show that SIA produced agars with properties at par with the commercial bacteriological agar sample. With the recommendation to further improve gel clarity, the application of solar photobleaching agar extraction process for Gracilariopsis heteroclada is very promising.
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    Isolation of Hyaluronic acid from yellowfin tuna (Thunnus albacares) eyeball
    Sumogod, Angeleca A. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2019-06)
    ABSTRACT Hyaluronic acid (HA) is commonly extracted from terrestrial and bacterial sources. However, due to the risk associated with either animal- and/or bacterial- derived contaminants and the laborious production processes that tend to compromise the quality of HA, research studies have recently shifted to the exploration of the presence of this polymer in marine resources and the enhancement of the protocols for HA production. Hence, this study focused on the isolation of HA from yellowfin tuna eyeballs. Results of the study showed that the optimum conditions for the isolation of HA from yellowfin tuna eyeballs are as follows: pretreatment of the raw material (acetone, formaldehyde and sodium acetate solution) prior to water extraction and incubation of the mixture for 24 h; tissue hydrolysis for a maximum of 6 h; a 3% CPC: 3M NaCl concentration for recovery and fractionation; and the use of 1:3 v/v supernatant: ethanol ratio for alcoholic precipitation. These results are expected to help maximize the benefits of the utilization of the tuna processing wastes in the country. Likewise, these findings may open a new opportunity for more cost-effective production of a valuable bioactive compound from marine source.
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    Bioactivities of protein hydrolysates from Chlorella sorokiniana
    Tejano, Lhumen A. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2018-06)
    ABSTRACT Microalgal proteins can be a good source of nutrients and compounds with bioactivities. In this study, proteins from Chlorella sorokiniana were isolated by pH shift technology and enzymatically hydrolyzed using pepsin, bromelain, and thermolysin to produce hydrolysates. Molecular characteristics of the hydrolysates were determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and amino acid analysis. After membrane ultrafiltration, bioactivities of the hydrolysates and peptide fractions were determined. Results revealed that thermolysin exhibited the highest degree of hydrolysis with 18.08 + 1.13%, followed by bromelain, and lastly by pepsin, after 4 h of hydrolysis. SDS-PAGE results showed that the hydrolysis generated peptides exhibited molecular weights of mostly <10 kDa of the hydrolysates, much less than those of the large and diverse proteins of the protein isolate. The essential amino acid indices (EAAIs) suggest that the hydrolysates could be considered as good quality protein sources. In vitro bioactivity assays, on the other hand, revealed that the pepsin peptide fraction of <5 kDa showed the highest DPPH radical scavenging activity (48.86 + 1.95%). Only pepsin hydrolysates and pepsin peptide fractions displayed inhibition to Staphylococcus aureus and Escherichia coli. However, there are no significant differences among the Angiotensin I Converting Enzyme (ACE) inhibitory and reducing power activities of the hydrolysates and peptide fractions. Both the protein hydrolysates and peptide fractions were observed to have satisfactory pH and heat stabilities. Overall, the results suggest that C. sorokiniana proteins can be a good alternative source of valuable compounds with pharmaceutical and nutraceutical application potentials.