Abstract

Coffee is one of the most consumed and preferred beverages in the world. Among the several polyphenols present in the coffee chlorogenic acids are major group of polyphenols which formed naturally due to esterification reaction during coffee processing. Chlorogenic acid shows nutritional and functional properties mainly due to its antioxidant, anti-inflammatory, antimicrobial, and antiviral activities; also it contributes bitterness and astringency note to the final beverage. In this investigation, for the retention of chlorogenic acid, different drying techniques such as spray drying, freeze drying, spray-freeze drying and refractance window drying were carried out on coffee bean extract for the production of instant soluble coffee powder. Powder characterization, morphology, particle size and solubility study was conducted for all the dried coffee powders obtained by various drying methods. Spray-freeze dried coffee powder displayed less particle size of 329 nm compared to powders (400-600 nm) obtained by other techniques. Solubility of spray-freeze dried powder in water was achieved within 10 sec. It was observed that maximum amount of chlorogenic acid has retained (84%) in the spray-freeze drying conditions than other drying methods. Release kinetics showed rapid release of chlorogenic acid (80%) at the end of 6 h in in vitro release condition.