Extraction, Isolation and Nutritional Quality of Coffee Protein.

Area of Science:

• Food Science
• Nutritional Biochemistry
• Protein Chemistry

Background:

• Coffee protein is purported to be rich in branched-chain amino acids, beneficial for sports nutrition and recovery.
• Limited data exists to substantiate these claims regarding coffee's amino acid composition.

Purpose of the Study:

• To investigate the extraction and isolation of protein concentrates from various coffee bean fractions.
• To determine the amino acid profile, caffeine, protein nutritional quality, polyphenol content, and antioxidant activity of these concentrates.
• To evaluate the protein nutritional quality, including in vitro digestibility and protein digestibility corrected amino acid score (PDCAAS).

Main Methods:

• Extraction and isolation of protein concentrates from green coffee, roasted coffee, spent coffee, and silver skin using alkaline extraction/isoelectric precipitation and alkaline extraction/ultrafiltration.
• Analysis of amino acid profile, caffeine content, polyphenol content, and antioxidant activity.
• Assessment of in vitro protein digestibility and PDCAAS.

Main Results:

• Alkaline extraction/ultrafiltration yielded higher concentrate yields and protein content than alkaline extraction/isoelectric precipitation.
• Green coffee bean protein concentrate exhibited higher protein content and superior in vitro digestibility and PDCAAS compared to other fractions.
• Contrary to prior findings, no coffee protein concentrate demonstrated high levels of branched-chain amino acids. All concentrates were rich in polyphenols with high antioxidant activity.

Conclusions:

• Green coffee bean protein concentrate offers significant nutritional potential due to its high protein content and digestibility.
• The previously reported high branched-chain amino acid content in coffee protein was not substantiated.
• Further research into the techno-functional and sensory properties of coffee protein is recommended for diverse food applications.