Abstract
The processing of maize generates a considerable amount of maize husks, which might have biological activities since most of the waste or by-products are rich sources of bioactive compounds. Nonetheless, no study has investigated the phenolic compounds of maize husk extracts and the feasibility of encapsulating the phenolic compounds of maize husk. In this study, the preparation conditions of the maize husk tea were optimized and the phenolic compounds were encapsulated with maltodextrin by freeze-drying, spray-drying, and microwave-drying. The optimum extraction conditions were 80 degrees C, 50 min, and 81 ml with 70.74 +/- 1.34 mg GAE/g, 0.61 +/- 0.02 mg ECE/g, 8.46 +/- 0.08 mmol TE/g and 20.61 +/- 0.55 mmol ISE/g for total phenolic content (TPC), total flavonoid content (TFC), DPPH radical scavenging activity and FRAP, respectively. The encapsulation productivities were 30.18-86.25%, 43.99-95.32%, 30.26-89.97%, and 32.71-71.64% for TPC, TFC, DPPH radical scavenging, and FRAP, respectively. The encapsulation efficiencies were found in the ranges of 88.29-98.21%. The encapsulation of phenolic compounds of maize husks was greatly affected by the drying technique. The freeze-drying was found as the most effective technique, providing the highest encapsulation productivity and efficiency. Maize husk extract and powder can be used to produce new antioxidant-enriched foods. Novelty impact statement The optimum extraction conditions to have maximum total phenolic content, total flavonoid content, DPPH radical scavenging activity, and ferric reducing power were found as 80 degrees C, 50 min, and 81 ml. The encapsulation of phenolic compounds of maize husks was found to be greatly influenced by the drying technique. The freeze-drying was the most efficient and provided the highest encapsulation productivity and efficiency.