engleski

Evaluation of Pectin Biofilms with Incorporated Phenolic Extracts of "Karoma" Spent Espresso Coffee Grounds

Coffee is one of the most consumed beverages in the world. Due to huge coffee production and consumption, the large amounts of by-products are generated. For instance, the spent coffee grounds (SCGs) are particularly fine, solid residues gained during the preparation of coffee brew from roasted and grounded coffee with hot water or steam. After brew consumptions, the remained residues are usually discarded into the environment. However, the SCG is the bio-substrate of the high biotechnological and food values due to ample chemical composition based on cellulose, hemicellulose, polysaccharides, proteins, polyphenols, and minerals. Considering the facts that SCG presented inexpensive, un-utilized biomass with ample chemical composition, in this study is showed the concept of SCG exploitation for phenols extraction with its subsequent incorporation into pectin base biofilms. The phenols were extracted from SCG by microwave-assisted extraction at t = 5 min, T = 50 °C and (ethanol) = 50 %. The obtained 50 % phenolic extracts were utilized for preparation of 5, 10 and 20 % (v/v) water extracts in which the 1 and 2 % pectin powder was dissolved. After addition of glycerol (50 and 70 %, v/v) and calcium chloride (2 %, v/v) the biofilms produced by casting method were evaluated in terms of their physical and mechanical properties. As results revealed the SCG extracts are successfully used for preparation of functional biofilms, and which combination of pectin, glycerol and phenolic extracts will be further use depends mostly on biofilms implementation. For instance, the biofilms with SCR extracts are darker than control, and consequently influenced on their appearance and acceptability by the consumer. The best mechanical properties in terms of tensile strength, elongation at the break, and Young modulus showed the biofilms prepared by 1 % pectin, 50 % glycerol and 2 % CaCl2 with addition of 10 and 20 % of phenolic extracts.

coffee by-products ; spent coffee grounds ; microwave-assisted extraction ; phenolic extracts ; pectin biofilms

nije evidentirano