Microencapsulation of highly concentrated polyphenolic compounds from purple corn pericarp by spray-drying with various biomacromolecules

Authors: ALI, AHMAD - University Of Missouri; WAN, CAIXIA - University Of Missouri; LIN, MENGSHI - University Of Missouri; Flint-Garcia, Sherry; VARDHANABHUTIB, BONGKOSH - University Of Missouri; SOMAVAT, PAVEL - University Of Missouri

Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2024
Publication Date: 6/8/2024
Citation: Ali, A., Wan, C., Lin, M., Flint Garcia, S.A., Vardhanabhutib, B., Somavat, P. 2024. Microencapsulation of highly concentrated polyphenolic compounds from purple corn pericarp by spray-drying with various biomacromolecules. International Journal of Biological Macromolecules. 272. https://doi.org/10.1016/j.ijbiomac.2024.132938.
DOI: https://doi.org/10.1016/j.ijbiomac.2024.132938

Interpretive Summary: Many plants contain bioactive compounds that can be used as replacements for synthetic food dyes and can offer potential health benefits to consumers, such as antioxidant, anticarcinogenic, anti-inflammatory, and neuroprotective properties. Once these compounds are extracted from the plant matter, they must be concentrated in a way that makes them suitable for industrial use but also preserves the desirable characteristics of the compounds. Spray-drying is a suitable method for the concentration and encapsulation of polyphenolic compounds. In this study, we extracted diverse polyphenolic compounds including anthocyanins, flavonoids, phenolic acids, and condensed tannins from the outside layer (called the pericarp) of purple corn kernels, and used a spray drying method to concentrate these compounds. We tested four carrier materials each at three different concentrations as part of the spray drying method, and then evaluated the structural, color, and thermal properties of the resulting products. We found that polyphenolic-rich samples encapsulated with either 1% gum arabic or 1% maltodextrin demonstrated superior properties, suggesting that these methods should be considered for further commercial-scale evaluations. The results of this study are important to researchers and corn processors as they add value to the US corn crop for farmers.

Technical Abstract: Colored corn pericarp contains unusually high amounts of industrially valuable phytochemicals, such as anthocyanins, flavanols, flavonoids, and phenolic acids. Polyphenols were extracted in an aqueous solution and spray-dried to produce microencapsulates using four carrier materials, namely, maltodextrin (MD), gum arabic (GA), methylcellulose (MC), and skim milk powder (SMP) at three concentrations (1, 2, and 3 %, respectively). The encapsulates were evaluated for their polyphenolic contents using spectrophotometric techniques and HPLC analyses, and their antioxidant properties were evaluated using four different assays. The physicochemical properties of encapsulates were analyzed by measuring the zeta potential (ZP), particle size distribution, water solubility index (WSI), water absorption index (WAI), and color parameters. Structural and thermal properties were evaluated using Fourier transform infrared spectroscopy (FTIR), optical profilometry, and differential scanning calorimetry (DSC) analyses. Comparative analysis of structural characteristics, particle size distribution, zeta potential, WSI, WAI, and aw of the samples confirmed the successful formulation of encapsulates. The microencapsulates embedded with 1 % concentrations of MD, MC, GA, or SMP retained polyphenolic compounds and exhibited noteworthy antioxidant properties. The samples encapsulated with GA or MD (1 %) demonstrated superior physicochemical, color, and thermal properties. Comprehensive metabolomic analysis confirmed the presence of 38 phytochemicals in extracts validating the spray-drying process.