The nonvolatile fraction of green coffee is composed primarily of water carbohydrates and fiber, proteins and free amino acids, lipids, minerals, organic acids, chlorogenic acids, trigonelline and caffeine. The coffee bean contains a large percent of protein – fourteen percent.Protein content in roasted coffee amount to about 10% when estimated by acid hydrolysis. The protein composition of coffee appears to vary little between the varieties of the bean, but a variation exists in the total protein content between green and roasted coffee, as protein content decreases and the physiochemical properties of the proteins are altered as a result of denaturation.
During roasting, some protein nitrogen is lost as a result of browning reactions between proteins and carbohydrates producing heterocyclic aroma volatiles.
The total amino acids content of the hydrolysates drops by about 30% because of considerable degradation.
The most important of the amino acids are glutamic acid, leucine, valine, aspartic acid, proline, glycine, phenylalanine, alanine, isoleucine and tyrosine.
Protein content in coffee
