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

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. The CSS extract can be successfully transformed into soluble powder using the spray drying process, based on product yield results (>50%). The optimum conditions are found as inlet temperature of 190°C, extract concentration of 10°Bx, and wall material composition (MN:AG) 10.5:9.5. The concentration treatment has a greater impact on the caffeine and chlorogenic acid content than the carrier material type. The findings reveal that the starting concentration has an impact on the final product's physical qualities. [ABSTRACT FROM AUTHOR]