Microencapsulation of young barley leaf extract with gum arabic, whey protein, and maltodextrin using freeze drying

New consumer preferences are driving food brands and beverage manufacturers worldwide to create enriched products that support the immune system and boost energy levels. This study explores the microencapsulation of young barley leaf extract, selected for its rich content of bioactive compounds, such as chlorophyll, phenolic compounds, vitamins, and minerals, which are known to offer antioxidant properties and potential health benefits. Ethanol was used as a solvent in the extraction process due to its effectiveness in extracting these compounds, though alternatives like water or supercritical CO2 may be considered in future research to address potential concerns regarding residual solvents in food products.

The microencapsulation was performed using a spray drying method with a combination of maltodextrin (20 degrees of hydrolysis), gum arabic, and whey protein as wall materials. The combination was optimized using response surface methodology and a one-way grid design, resulting in 14 different wall formulations. The physicochemical properties of the resulting microcapsules—moisture content, microencapsulation efficiency, chlorophyll content, phenolic compounds, and antioxidant activity—were evaluated, with the results indicating that a mixture of maltodextrin, gum arabic, and whey protein significantly enhances these properties compared to single-wall coatings.

Numerical and graphical optimization identified the optimal wall composition as 63.45% maltodextrin, 19.25% gum arabic, and 17.30% whey protein. Stability tests of chlorophyll microcapsules conducted over 35 days at varying temperatures (4°C and 25°C) and humidity levels (52% and 75%) demonstrated a linear decrease in chlorophyll content, with better preservation observed at lower temperature and humidity levels. Microcapsules composed of 66.67% maltodextrin, 16.67% whey protein, and 16.67% gum arabic showed the lowest reaction rate constant and the longest chlorophyll storage half-life (216.56 days), indicating the highest stability. Under conditions of 4°C and 52% humidity, these microcapsules exhibited the smoothest surfaces, with minimal cracks and agglomeration.