title: Composition and structure of tuber cell walls affect in vitro digestibility of potato (Solanum tuberosum L.).
abstract: The digestibility of starchy foods, such as potatoes, can be characterized by the proportion of starch that is rapidly digestible by in vitro hydrolysis (rapidly digestible starch, RDS). This study evaluated the RDS content in a potato germplasm collection consisting of 98 genotypes and identified three advanced lines, Crop39, Crop71 and Crop85, where cooked potato RDS content was significantly lower than that of their respective isolated starches (P < 0.05). In Crop39, Crop71 and Crop85, the properties of their isolated starch did not differ significantly from that of five control lines with higher RDS contents. Cell wall analyses revealed that, compared with other lines tested, Crop39, Crop71 and Crop85 had at least four times the amount of rhamnogalacturonan-I (RG-I) galactan side-chains that were very firmly attached to the wall and requiring 4 M KOH for extraction. Pectin solubilization during cooking was also remarkably low (2-4%) in these three lines compared with other lines tested (7-19%). The findings suggest that possession of higher amounts of RG-I galactan that interact strongly with cellulose may provide a sturdier wall that better resists solubilization during cooking, and effectively impedes access of digestive enzymes for starch hydrolysis in an in vitro model.
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand. jovyn.frost@plantandfood.co.nz.
authors.forename: Jovyn K T
authors.identifier: http://orcid.org/0000-0002-4747-5420
authors.initials: JK
authors.lastname: Frost
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Qld 4072, Australia.
authors.forename: Bernadine M
authors.initials: BM
authors.lastname: Flanagan
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand. jovyn.frost@plantandfood.co.nz.
authors.forename: David A
authors.initials: DA
authors.lastname: Brummell
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand. jovyn.frost@plantandfood.co.nz.
authors.forename: Erin M
authors.initials: EM
authors.lastname: O'Donoghue
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand. jovyn.frost@plantandfood.co.nz.
authors.forename: Suman
authors.initials: S
authors.lastname: Mishra
authors.affiliation: ARC Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Qld 4072, Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gidley
authors.affiliation: The New Zealand Institute for Plant & Food Research Limited, Food Industry Science Centre, Private Bag 11600, Palmerston North 4442, New Zealand. jovyn.frost@plantandfood.co.nz.
authors.forename: John A
authors.initials: JA
authors.lastname: Monro
mesh_terms: D002473:Cell Wall / Q000737:chemistry* / Q000502:physiology*; D059828:Plant Cells / Q000502:physiology*; D035281:Plant Tubers / Q000166:cytology*; D011198:Solanum tuberosum / Q000166:cytology*; D013213:Starch / Q000737:chemistry
chemical_list: D013213:Starch