o Evaluation of different procedures for obtaining bioactive compounds from globe artichoke wastes

LIA GERSCHENSON; ELIANA FISSORE; SUSANA BOTTINI; ANA M. ROJAS; PABLO HEGEL; CINTHIA SANTO DOMINGO

York

Congreso; 11th International Conference on Renewable Resources & Biorefineries; 2015

Ghent University, Biorenewables Development Centre, University of York (Green Chemistry Center of Excellence)

Artichoke (Cynara cardunculus var. scolymus) is consumed worldwideas both a fresh and a canned delicacy product. Its edible fraction isconstituted by the enlarged receptacle and the tender thickened bract based onthe head and represents less than 15-20% of the total plant biomass.Plant tissues discarded at harvesting orafter industrialization constitute a valuable and renewable source ofbiopolymers and bioactive compounds. The upgrading of vegetable wastes cancontribute to reduce pollution and to add value to the commodity production.The alcohol insoluble residue (AIR) isconstituted by the cell wall biopolymers, and its extraction from plant tissuesis a way of obtaining a concentrate of polysaccharides which can be used infood products as dietary fiber and/or to modify the rheology. Also, the AIRusually contains associated polyphenols which can provide a natural antioxidantactivity. The objective of this research was the evaluation of three methodsfor the extraction of AIR with ethanol from the artichoke bract powderpreviously obtained by dehydration (85ºC, 2.5 h) and milling-sieving:1) traditional heating in 80.0% (v/v) ethanolunder boiling (1 h), 2) microwave heating (250 Watt, 80ºC, 12 min)in 80.0% (v/v) ethanol,3) CO2-subcritical (45.5bar-operative pressure) assisted extraction using 99.9% (w/w) ethanol.It was determined that the CO2-subcritical assisted methodproduced the highest yield of AIR (95g/100g bract powder). AIRs wereessentially constituted by polysaccharides (72-93%), proteins, lignin (»16%) andpolyphenols. The inulin content varied between 7.9% for the AIR extractedthrough traditional heating and »4%. Also, the highest proportions of cellulose (22%) and proteins (8.5%)were obtained with this procedure but it produced the lowest proportion ofuronic acids (3.9%). Microwaves and the CO2-subcritical methodpermitted to obtain AIRs with more pectin (uronic acids), as well as with somehigher polyphenol contents (530-570mg/100gAIR) and they also presented highradical scavenging activity (DPPH assay) (100-170 mg trolox/100gAIR), being theAIR extracted through method 3 the one with the highest reducing capacity (FRAPassay). The procedures tested gave origin to high yields of AIRs with importantpolyphenol contents and antioxidant activities.