Encapsulation of hop (Humulus lupulus L.) essential oil for controlled release in the non-alcoholic beverage application

In order to increase the stability of hop (Humulus lupulus L.) essential oil (HEO) and diversify its application into hot beverages, CAPSUL (R), modified food starch, was used as the wall material to encapsulate HEO at the mass ratio of 2:1 through spray drying under 180 degrees C. The resultant microcapsules were applied to the non-alcoholic hop tea for the first time and their release kinetics in this matrix were analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that the reconstituted HEO emulsion possessed fine droplet size (3.295 mu m) and high zeta potential (-22.50 mV). The resultant HEO microcapsules exhibited low moisture content (1.249%), suitable bulk density (0.2934 g/mL), good swelling capacity (2.235 g/g dry solids), low color difference (6.310), desirable morphological characteristics, high encapsulation efficiency (92.02-95.45%) and high flavor retention (57.13-71.15%). Each target aroma compound had its specific release behavior and mechanism from HEO microcapsules, among which beta-myrcene and methyl octanoate showed the highest and lowest cumulative release respectively. This might be associated with their different volatilities, polarities, function groups and molecular sizes, or their varying hydrogen-bond formation capability at the entrance of starch helix. Most importantly, HEO microcapsules showed significant aroma increasing and stabilizing effects on the hop tea product during storage. These ideal characteristics of HEO microcapsules demonstrated the great potential of diverse essential oil microcapsules as the promising flavoring agents in a variety of hot beverage matrices.

Automated summary

In this study, CAPSUL (R), a modified food starch, was used to encapsulate hop essential oil (HEO) through spray drying. The resulting microcapsules demonstrated favorable physicochemical properties and release performance, significantly enhancing and stabilizing the aroma of non-alcoholic hop tea products.