Microencapsulation of phytochemical-rich colored corn cellulosic biomass extracts for natural red colorants with enhanced stability and antioxidant activities

Abstract A comparative evaluation of cellulosic biomass from colored corn varieties including twenty cobs and seven tassels was performed to quantify their polyphenolic contents and corresponding antioxidant activity. Spectrophotometric analysis and antioxidant screening with four distinct protocols identified five polyphenol-rich cob varieties, whereas the quantified amounts in tassels were relatively lower. Variety V2458-1 contained the highest phytochemical content with total anthocyanin, condensed tannins, total phenolics, and total flavonoid concentrations of 61.22, 530.14, 111.56, and 35.90 mg per g of cob powder, respectively. HPLC and UHPLC-MS analyses were performed and 31 phytochemicals including 11 anthocyanins, 9 phenolic acids, and 11 flavonoids were identified. Ultrasonic-assisted microencapsulation with gum arabic (1%) as a coating material was used to formulate shelf-stable freeze-dried powders. Due to the higher concentrations of xylan, gum arabic was required as a coating material for producing free-flowing extracted powders. The developed powders were systematically analyzed for phytochemical retention, antioxidant capacity, and microstructural characteristics. Morphological analysis confirmed the formation of stable microcapsules, indicating effective encapsulation and protection of sensitive phytochemicals. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) revealed hydrogen-bond interactions between carrier materials and the extract, contributing to structural stability of the encapsulation matrix. The resulting powders had improved physicochemical stability, higher phytochemical content, and strong antioxidant potential, validating their application as natural red colorants and functional food ingredients in line with the circular bioeconomic paradigm.