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UPV Theses and Dissertations

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Committee Member: search.filters.committeemember.Nuñal, Sharon N.Discipline: search.filters.discipline.Fish Processing Technology

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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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    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.