Unlocking the potential of hop extracts through microencapsulation: Role of wall materials and drying technologies

This study explores the effect of freeze-(FD) and spray-(SD) drying with maltodextrin, Arabic gum, and β-cyclodextrins (βCD), in producing microencapsulated hop extracts (MHEs) to use as food additives/ingredients with functional, techno-functional and stability properties. MHEs were characterized (HPLC-DAD analysis) for the content of bitter acids, polyphenols, prenylflavonoids, and antimicrobial and antioxidant (FRAP, ABTS assay) activities. MHEs' stability was tested under thermal stress conditions. Overall, FD was more effective in preserving bitter acids, whereas SD represented a cost-effective alternative when combined with suitable carriers. βCD enhanced the retention of polyphenols, bitter acids, and prenylflavonoids, particularly in SD samples. FD-MHEs showed the highest antioxidant activity, especially those formulated with βCD. All MHEs exhibited strong antimicrobial activity against Listeria monocytogenes (MIC = 0.0078 mg/mL; MBC = 0.0313 mg/mL) but were ineffective against Pseudomonas fluorescens (MIC and MBC >2.5 mg/mL). Under stress conditions, FD-MHEs better retained antioxidant properties than SD-MHEs, while βCD limited α-acid degradation and isomerization.