title: Mashed potatoes enriched with soy protein isolate and inulin: chemical, rheological and structural basis.
abstract: Soy protein isolate is typical vegetable protein with health-enhancing activities. Inulin, a prebiotic no digestible carbohydrate, has functional properties. A mashed potato serving of 200 g with added soy protein isolate and/or inulin concentrations of 15-60 g/kg provides from 3 to 12 g of soy protein isolate and/or inulin, respectively. Currently, no information is available about the possible texture-modifying effect of this non-ionizable polar carbohydrate in different soy-based food systems. In this study, the effect of the addition of soy protein isolate and inulin blends at different soy protein isolate: inulin ratios on the degree of inulin polymerization and the rheological and structural properties of fresh mashed and frozen/thawed mashed potatoes were evaluated. The inulin chemical structure remained intact throughout the various treatments, and soy protein isolate did not affect inulin composition being a protein compatible with this fructan. Small-strain rheology showed that both ingredients behaved like soft fillers. In the frozen/thawed mashed potatoes samples, addition of 30 : 30 and 15 : 60 blend ratios significantly increased elasticity (G' value) compared with 0 : 0 control, consequently reducing the freeze/thaw stability conferred by the cryoprotectants. Inulin crystallites caused a significant strengthening effect on soy protein isolate gel. Micrographs revealed that soy protein isolate supports the inulin structure by building up a second fine-stranded network. Thereby, possibility of using soy protein isolate and inulin in combination with mashed potatoes to provide a highly nutritious and healthy product is promising.
authors.affiliation: Department of Characterization, Quality and Food Safety, Institute of Food Science, Technology and Nutrition (ICTAN-CSIC), Madrid, Spain.
authors.forename: M D
authors.initials: MD
authors.lastname: Alvarez
authors.forename: M D
authors.initials: MD
authors.lastname: Olivares
authors.forename: M
authors.initials: M
authors.lastname: Blanch
authors.forename: W
authors.initials: W
authors.lastname: Canet
mesh_terms: D003296:Cooking; D005527:Food, Fortified / Q000032:analysis*; D007328:Insulin / Q000737:chemistry*; D012212:Rheology; D011198:Solanum tuberosum / Q000737:chemistry*; D030262:Soybean Proteins / Q000737:chemistry*
chemical_list: D007328:Insulin; D030262:Soybean Proteins
keywords: Soy protein isolate; long-chain inulin; microstructure; viscoelasticity