title: Effect of extraction pH on heat-induced aggregation, gelation and microstructure of protein isolate from quinoa (Chenopodium quinoa Willd).
abstract: The aim of this study was to determine the influence of extraction pH on heat-induced aggregation, gelation and microstructure of suspensions of protein isolates extracted from quinoa (Chenopodium quinoa Willd). Quinoa seed protein was extracted by alkaline treatment at various pH values (pH 8 (E8), 9 (E9), 10 (E10) and 11 (E11)), followed by acid precipitation. The obtained protein isolates were freeze dried. The protein isolates E8 and E9 resulted in a lower protein yield as well as less protein denaturation. These isolates also had a higher protein purity, more protein bands at higher molecular weights, and a higher protein solubility in the pH range of 3-4.5, compared to the isolates E10 and E11. Heating the 10%w/w protein isolate suspensions E8 and E9 led to increased aggregation, and semi-solid gels with a dense microstructure were formed. The isolate suspensions E10 and E11, on the other hand, aggregated less, did not form self-supporting gels and had loose particle arrangements. We conclude that extraction pH plays an important role in determining the functionality of quinoa protein isolates.
authors.affiliation: Food and Biobased Research, Wageningen University and Research Centre, P.O. Box 17, 6700 AA Wageningen, Netherlands. Electronic address: geraldine.ruiz@wur.nl.
authors.forename: Geraldine Avila
authors.initials: GA
authors.lastname: Ruiz
authors.affiliation: Food Quality and Design Group, Wageningen University and Research Centre, P.O. Box 9101, 6700 HB Wageningen, Netherlands.
authors.forename: Wukai
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Food Quality and Design Group, Wageningen University and Research Centre, P.O. Box 9101, 6700 HB Wageningen, Netherlands.
authors.forename: Martinus
authors.initials: M
authors.lastname: van Boekel
authors.affiliation: Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Minor
authors.affiliation: Food and Biobased Research, Wageningen University and Research Centre, P.O. Box 17, 6700 AA Wageningen, Netherlands.
authors.forename: Markus
authors.initials: M
authors.lastname: Stieger
mesh_terms: D027465:Chenopodium quinoa / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D011489:Protein Denaturation; D012639:Seeds / Q000737:chemistry; D012995:Solubility
chemical_list: D005782:Gels; D010940:Plant Proteins
keywords: Aggregation; Denaturation; Extraction; Gelation; Protein; Quinoa; Solubility