Ultrasound and Microwave-assisted Extraction of Proteins from Coffee Green Beans: Effects of Process Variables on the Protein Integrity

The demand for proteins is constantly increasing and green extraction methodologies are needed to achieve environmental sustainability goals. The recovery of the by-products of the agri-food chain has also become a priority from a circular economy perspective. Some by-products are still little exploited for the extraction of proteins, such as coffee by-products. In this work, various innovative extraction technologies were applied to recover the protein fraction from the non-compliant coffee green beans (CGB), using a methodological approach that allowed to correlate the process parameters with the final quality of the extracted proteins. The ultrasound-assisted extraction (UAE) technique has been shown to have a minor impact on the quality of the proteins, thanks to the possibility of refrigerating the system, while the microwave-assisted extraction (MAE) shows a certain degree of degradation due to the high temperatures reached. The results indicate that strict temperature control is required during alkaline extraction to preserve the quality of the protein fraction.

Automated summary

The demand for proteins is increasing, calling for green extraction technologies for environmental sustainability. Recovering protein from agri-food by-products, including coffee by-products, is important for circular economy. This study applied innovative extraction technologies to extract protein from non-compliant coffee green beans, and found that ultrasound-assisted extraction had minor impact on protein quality due to refrigeration, while microwave-assisted extraction caused degradation due to high temperatures. Strict temperature control is required during alkaline extraction to preserve protein quality.