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Title
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SOYBEAN ISOFLAVONES AS A NATURAL PRESERVATIVE THROUGH ANTI-MICROBIAL ACTION FOR FRESH Oreochromis niloticus, Linnaeus 1758 (NILE TILAPIA)
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Author(s)
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AMACANIN, GLYCE A.
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PAGLINAWAN, JUN RUSSELLE L.
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CIMAFRANCA, PRINCE CARL D.
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Affiliation
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Misamis University
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Degree Program
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Bachelor of Science in Medical Technology
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Contributor
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Villantes, Yunalyn L. PhD - Adviser
Enguito, Marie Roselynn C., MSc Bio - Panel member
Parba, Meliza PhD - Panel member
Lao, Karl Maxel O. RMT, MSc MLS - Chairman
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Year
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2026
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Abstract
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Fresh Oreochromis niloticus is highly perishable due to microbial growth, enzymatic activity, and oxidation, making proper preservation essential for maintaining fish quality and safety. This study aimed to evaluate the effectiveness of commercially available soybean oil as a natural preservative for fresh O. niloticus by assessing its antimicrobial activity and the physical appearance of the fish. A quantitative experimental design was used, wherein fresh tilapia samples were divided into three groups: soybean oil
treated samples, untreated negative control samples, and refrigerated positive control samples. Swab samples were collected from the gills, body, and gut at 2, 6, 10, and 24 hours, inoculated on Nutrient Agar and MacConkey Agar, and analyzed using colony-forming unit counts per plate (CFU/plate), One-Way ANOVA, and Tukey HSD post hoc test. In Nutrient Agar, significant differences (p <0.05) among treatment groups were observed at all storage periods, with the soybean oil-treated samples showing lower bacterial counts than the negative control at 6, 10, and 24 hours. In MacConkey Agar, significant differences were observed at 2, 10, and 24 hours, while no significant difference (p < 0.05) was observed at 6 hours. The soybean oil-treated samples
showed lower Gram-negative bacterial counts than the negative control at 10 and 24 hours, suggesting possible delayed and selective antimicrobial activity. However, the treatment did not
consistently produce the lowest bacterial count in all time intervals and media. In terms of physical appearance, refrigeration remained the most effective method. At the same time, soybean oil-treated samples exhibited only moderate quality and did not differ significantly from untreated samples in most physical parameters. The study concludes that commercially available soybean oil showed limited, selective, and time-dependent antimicrobial potential, but it cannot fully replace refrigeration. Further studies using controlled soybean oil concentrations, phytochemical screening, bacterial identification, longer observation periods, and combined refrigeration treatment are recommended.
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Keywords
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Antimicrobial, delayed, preservative, soybean oil, treatment
