Design of encapsulation method for chlorogenic acid and caffeine in coffee waste by-product

Phytochem Anal. 2023 Jan 24. doi: 10.1002/pca.3207. Online ahead of print.


Introduction: Coffee silver skin (CSS) is a thin covering over green coffee seeds inside coffee cherry. It is a good source of bioactive compounds like chlorogenic acid and caffeine. It is produced as a by-product of the roasting process.

Objective: The goal of this study is to apply spray drying method to encapsulate 5-O-caffeoylquinic acid (chlorogenic acid) and caffeine extracted from CSS.

Methods: The main-plots for optimisation were feed solid concentration (2.5, 5, 10°Bx), and the sub-plots of the whole-plot were carrier material type (maltodextrin, modified starch, arabic gum) and inlet air temperature (130, 160, 190°C). Responses included were drying yield, chlorogenic acid concentration, caffeine content, Carr index, and solubility values.

Results: Suitable conditions were spray drying inlet temperature of 190°C, extract concentration of 10°Bx, and wall material composition [modified starch/arabic gum (MS:AG)] 10.5:9.5. As the feeding CSS extract concentration increased, the amount of chlorogenic acid and caffeine in the final powder increased, while the powder's flow characteristics improved.

Conclusions: The concentration stage might be used to produce free-flowing powdered particles with good bioactive retention for use in the food processing industry.

Keywords: bioactive compounds; caffeine; coffee silver skin powder; encapsulation; spray drying.