Vol.:(0123456789) 1 3 European Food Research and Technology https://doi.org/10.1007/s00217-019-03242-y ORIGINALPAPER Rheological behavior of soluble dietary fber fractions isolated from artichoke residues Cinthia Santo Domingo 1,2  · Ana M. Rojas 1,3  · Eliana N. Fissore 1,3  · Lía N. Gerschenson 1,3 Received: 9 July 2018 / Revised: 2 December 2018 / Accepted: 8 December 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Cynara cardunculus var. scolymus agroindustrial by-products (stems, outer bracts, leaves) constitute 80% of the plant. These by-products may be recovered for the extraction of food additives and nutraceuticals. In this research, the rheological behavior of soluble dietary fber fractions isolated from bracts (B) and stems (S) of artichoke was studied. Fractions were isolated by means of a heat treatment followed by processing with sodium citrate bufer (S1, B1) or bufer/protease (S2, B2) or hemicellulase (S3, B3) or both enzymes (S4, B4). They were composed, mainly, by pectin (degree of methylation, DM ≤ 53%) and inulin. When dissolved in water (2.00% w/v) with Ca 2+ (40 mg/g pectin), fractions were sensitive to the ion showing shear thinning fow, with initial yield stress in the case of B2, B3 or S3. Citrate bufer extracted fractions (B1, S1) showed the highest viscosities, whereas extraction with bufer and both enzymes (B4, S4) produced the least viscous fber fractions. At rest assays revealed the formation of gel-like networks that were stronger, in general, in the presence of higher pectin and inulin content, homogalacturonan proportion, and low methylation degree. Leftovers of artichoke can be used to extract soluble dietary fber fractions that might be utilized as natural thickeners and gelling agents in foods, pharmaceutical and cosmetics, helping to add value to raw materials and to close the bioeconomy loop in relation to this plant. Keywords Cynara cardunculus · Protease and hemicellulase · Pectin and inulin · Rheological behavior Introduction Globe artichoke (Cynara cardunculus var. scolymus), a thistle-like vegetable, is an ancient perennial plant species (Asteraceae) native to the Mediterranean Basin. Its annual global production of approximately 1.5 million metric tonnes is dominated by Southern Europe and, in particular, by Italy. In other parts of the world, Egypt, China, Peru, Argentina and the USA are main producers [1]. It is culti- vated for its large immature fower heads. The edible parts of the plant are the tender inner bracts and the receptacle, com- monly known as “heart” [2], which is consumed worldwide, as fresh or processed product [3, 4]. The artichoke canning industry generates large amounts of industrial waste, con- sisting mainly of the stems and external parts of the fowers (bracts) of the artichoke plant. In Argentina, the area planted with globe artichoke is concentrated in the horticultural areas of La Plata (Buenos Aires province), Rosario (Santa Fe province), and Mendoza and San Juan provinces. The production is designed mainly for the fresh produce market [5]. Artichoke industrial by- products (stems, outer bracts, leaves) represent about 80% of the biomass and are generally used in the production of animal feed, particularly silage. Vegetable tissues discarded at harvesting increase the amount of by-products that may be recovered for using as raw material for the extraction of food additives and nutraceuticals [6]. Globe artichoke has been shown to be a good source of inulin, pectic polysaccharides and phenolic compounds and can be used as a fber supple- ment for food processing [6–8]. Pectins constitute a family of complex polysaccharides present in all plant primary cell walls. The composition, structure and molecular weight will determine its function- ality and physiological properties [9]. According to Willats * Lía N. Gerschenson lia@di.fcen.uba.ar 1 Laboratorio de Optimización de la Calidad de Alimentos Preservados, Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, LOCAP, Universidad de Buenos Aires, Buenos Aires, Argentina 2 National Research Council of Argentina, CONICET, Buenos Aires, Argentina 3 CONICET, Buenos Aires, Argentina