EVALUATION OF DIFFERENT PROCEDURES FOR OBTAINING THE ALCOHOL INSOLUBLE RESIDUES (AIR) FROM GLOBE ARTICHOKE WASTES

SANTO DOMINGO C.; HEGEL, P.; ROJAS, A.M.; BOTTINI, S.; GERSCHENSON, L.

York

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

University of York

The artichoke (Cynara cardunculus var. scolymus) edible part is the enlarged receptacle and the tender thickened bract based on the head. It is used worldwide as both a fresh and canned delicacy product. The edible fraction is less than 15?20% of the total plant biomass. Plant tissues discarded at harvesting or after industrialization constitute a valuable and renewable source of biopolymers and bioactive compounds. The upgrading of vegetable wastes can contribute to reduce pollution and to add value to the commodity production.The AIR is constituted by the cell wall biopolymers, and its extraction from plant tissues is a way of obtaining a concentrate of polysaccharides which can be used in food products as dietary fiber and/or to modify the rheology. Also, the AIR usually contains associated polyphenols which can provide a natural antioxidant activity. The objective of this research was the evaluation of three methods for the extraction of AIR with ethanol from the artichoke bract powder previously obtained by dehydration (85ºC, 2.5 h) and milling-sieving:1) traditional heating in 80.0% (v/v) ethanol under boiling (1 h), 2) microwave heating (250 Watt, 80ºC, 12 min) in 80.0% (v/v) ethanol,3) CO2-subcritical (45.5. bar-operative pressure) assisted extraction using 99.9% (w/w) ethanol.It was determined that the CO2-subcritical assisted method produced the highest yield of AIR (95g/100g bract powder). AIRs were essentially constituted by polysaccharides (72-93%), proteins, lignin (16%) and polyphenols. The inulin content varied between 7.9% for the AIR extracted through 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 of uronic acids (3.9%). Microwaves and the CO2-subcritical method permitted to obtain AIRs with more pectin, as well as with some higher polyphenol content (530-570mg/100gAIR). They presented high radical scavenging activity (DPPH assay) (100-170 mg trolox/100gAIR), showing the highest reducing capacity (FRAP assay) the AIR extracted through method 3. The procedures tested gave origin to high yields of AIRs with important polyphenol contents and antioxidant activities.