Unveiling the impact of onion bulb size on biochemical composition and antioxidant potential: Insights into varietal...

Onion (Allium cepa L.) is a vegetable widely consumed worldwide. It is valued for its diverse bioactive compounds. However, the relationship between bulb size and biochemical traits remains unclear. In this study, 15 onion genotypes were classified into small, medium, and large bulbs to investigate their antioxidant compounds, antioxidant capacity, and key biochemical parameters. Large bulbs exhibited the highest levels of total soluble solids (7.1°Brix), pungency (12 μmol pyruvic acid/g FW), and total phenolic compounds (102 mg/100 g FW). Small bulbs had higher dry matter (8.8 %) and vitamin C (41 mg/100 g FW). Titratable acidity (TA) was significantly higher in small bulbs (0.24 g/100 g), resulting in a lower flavor index (FI), calculated as the ratio of TSS to TA. The FI reflects the sweetness-to-acidity balance and is useful for classifying genotypes according to flavor preference. These findings provide insights for breeding programs targeting health traits.