Impact of Stir-frying with Different Vegetable Oils on Phytochemical Composition and Pyruvic Acid Content in Allium sativum and Allium ampeloprasum Cultivars

Abstract

Background: Thermal processing can markedly affect the stability of bioactive phytochemicals in Allium vegetables, which are valued for their health-promoting properties. Aim: This study aimed to evaluate the impact of stir-frying using different vegetable oils on pyruvic acid content and phytochemical composition of Allium sativum and Allium ampeloprasum cultivars. Methods: Bulb samples of A. sativum (AS1, AS2) and A. ampeloprasum (AA1, AA2) were stir-fried using sesame, refined sunflower, and olive oils at controlled temperatures (160–200°C). Extracts were prepared using solvents of varying polarity. Pyruvic acid content was determined spectrophotometrically, and phytochemical profiling included qualitative screening, total phenolic content (TPC), total flavonoid content (TFC), and FTIR analysis. Statistical analysis was performed using one-way ANOVA followed by Tukey’s post-hoc test (p < 0.05). Results: Stir-frying significantly reduced pyruvic acid, TPC, and TFC compared to raw controls (p < 0.05). Sesame oil exhibited the highest retention of pyruvic acid (17.81 ± 0.1 μmol g-1 in AS1) and phytochemicals, whereas sunflower oil showed the greatest degradation. Non-polar solvent extracts demonstrated enhanced recovery of bioactive compounds, and FTIR analysis confirmed the preservation of key functional groups in sesame oil–processed samples. Conclusion: The type of cooking oil significantly influences phytochemical stability during stir-frying, with sesame oil providing superior protection against thermal degradation and better preservation of nutritional quality in Allium species. Major Findings: Sesame oil retained the highest levels of phytochemicals and pyruvic acid. Sunflower oil showed maximum degradation of bioactive compounds. Oil composition critically influences phytochemical stability during cooking.