Edible flowers efficiency to boost the thermal oxidation stability of soybean oil: Polyphenolic and antioxidant insights

Indigenous people in Bangladesh's Chittagong hill regions use Curcuma longa and Zingiber officinale flowers in their traditional meals due to their vibrant color, exquisite flavor, and fragrant perfume. The induction time of soybean oil enriched with the ethanolic extract of the flower of Curcuma longa (CFE), Zingiber officinale (ZFE), and butylated hydroxytoluene (BHT) was compared to determine the effect on oxidation stability. The study also measured bioactive polyphenolic components, total flavonoid (TFC), total tannin (TTC), total phenolic (TPC), total antioxidant activity (TAA), and IC50 values of ZFE and CFE. The induction time was shorter for both 5 % of CFE (6.97 h) and ZFE (6.85 h) than 0.02 % BHT (7.18 h) but longer than 0.01 % BHT (6.49 h). TPC in CFE (37.57 mg GAE/g) was higher than in ZFE (26.14 mg GAE/g). TAA and IC50 values were not significantly different. TFC in ZFE (28.8 mg QE/g) was higher than in CFE (27.63 mg QE/g). The major polyphenols of CFE and ZFE were trans-cinnamic acid (12,209 and 678 mu g/g); catechin hydrate (1758 and 1821 mu g/g); p-coumaric acid (1186 and 126 mu g/g); and quercetin (1309 and 1773 mu g/g), respectively. This study demonstrated that antioxidants in flower extract improve fat and oil oxidation stability.