Profile of Free and Conjugated Phenolic Compounds of Okra Pods Subjected to High-Humidity Hot-Air Impingement Blanching (HHAIB)

The profiles of free, ester-bound, and glycoside-bound phenolic compounds in okra pods (OP) subjected to high-humidity hot-air impingement blanching (HHAIB) for up to 120 s were analyzed using a micro-HPLC-QTRAP/MS/MS method. Fourteen phenolic acids and ten flavonoids were identified in both unprocessed and HHAIB-treated samples. Phenolic acids and flavonoids were mainly present in free and ester-bound forms. HHAIB treatment up to 60 s resulted in a progressive decrease in the contents of free, ester-bound, and glycoside-bound phenolic acids. In contrast, the content of free flavonoids initially increased after 5 s of HHAIB, followed by a gradual decrease in conjugated forms with prolonged treatment. The results indicate that blanching for 90 s ensured the highest partial recovery of free and conjugated phenolic acids after initial loss as compared to the non-treated material. These findings demonstrate that HHAIB treatment can effectively modulate the phenolic composition of okra pods and help identify optimal processing conditions for maximizing the retention of bioactive compounds.