engleski

Spray-drying encapsulation of nettle and fennel bioactive molecules

Both nettle and fennel are valuable plants with high content of bioactive molecules. Beneficial effects of nettle are mainly attributed to polyphenols, while fennel is recognized for its essential oil (EO) content. Although chemically different, both nettle extract and fennel EO are characterized with loss of stability and bioactivity during prolonged storage and processing. Spray drying, as a method for encapsulation of both hydrophilic and lipophilic compounds, can provide stabilization, preservation as well as controlled release and delivery of both nettle bioactives and fennel EO. Therefore, the aim of this study was to evaluate and optimize the spray drying encapsulation of nettle leaves extract and fennel EO using different carrier materials and drying temperatures. Nettle leaves extract was obtained by microwave-assisted extraction and encapsulated using maltodextrin (MD) and β-cyclodextrin (CD) as single carriers or in mixtures with gum arabic (GA) in proportion 1:1 and 3:1, respectively. Carriers were used in sample:carrier ratios 1:1, 1:2 and 1:3, while spray drying was performed at 120, 160 and 200 °C. Fennel EO was spray dried at same temperatures and emulsified with following carrier mixtures, MD:CD, MD:GA and CD:GA in proportions 1:1, 1:3 and 3:1 at fixed EO:carrier ratio of 1:3. The highest yield and encapsulation capacity for nettle leaves extract was achieved with addition of MD as a carrier agent in ratio 1:3 at 120 °C, while optimal encapsulation conditions for fennel EO were mixture of CD:GA in proportion 3:1 at 200 °C which resulted in the highest EO retention in microcapsules and the highest encapsulation efficiency. The differences in obtained encapsulation conditions arise from the differences in chemical properties of encapsulated materials, showing that carrier agents such as CD and GA are suitable for non-polar constituents of EO, while MD is more efficient in encapsulation of polar compounds such as polyphenols. The encapsulation of nettle extract and fennel EO provided preservation and stabilization of respective bioactive compounds and increased their bioavailability in encapsulated form, indicating the great potential of such microcapsules for further application in food industry.

encapsulation ; essential oil ; fennel ; nettle ; polyphenols

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