Date of Completion

2025

Document Type

Thesis

Degree Name

Bachelor of Science in Life and Health Sciences

Keywords

Antioxidants, Vitamin C, Food Preservation, DPPH, UV-Vis Spectrophotometry, Freezing, Juicing, Drying, Pickling

Abstract

This study investigated how various preservation techniques, juicing, freezing, drying, and pickling, influence the antioxidant activity and vitamin C concentration of five fruits: strawberries, mangoes, blueberries, oranges, and pineapples. These fruits were selected due to their high nutritional value and common use in preserved forms. The study aimed to assess nutrient stability after processing and identify which methods best retain health-promoting compounds. Antioxidant activity was assessed through the DPPH radical scavenging assay, and vitamin C was measured using UV-Visible spectrophotometry. One-way ANOVA with Tukey’s HSD post hoc test was applied to evaluate statistical differences between fresh and treated samples (p < 0.05). Freezing was found to retain the highest levels of both nutrients, while drying resulted in the most significant losses in antioxidant activity. For pineapples, antioxidant activity differed significantly among treatments (p = 0.002), with dried samples showing the lowest activity. In contrast, strawberries, mangoes, blueberries, and oranges showed no statistically significant differences in antioxidant activity (p > 0.05), despite numeric declines. Significant differences in vitamin C content were found in all fruits except mangoes (p = 0.206). Dried samples showed the highest concentrations, largely due to the concentration effect from moisture loss rather than true nutrient preservation. Overall, these findings demonstrate that nutrient retention is both fruit-specific and method-dependent, underscoring the need to select appropriate preservation techniques to maintain the health benefits of fruits.

First Advisor

Joseph P. Bendo

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