title: Influence of diurnal photosynthetic activity on the morphology, structure, and thermal properties of normal and waxy barley starch.
abstract: This study investigated the influence of diurnal photosynthetic activity on the morphology, molecular composition, crystallinity, and gelatinization properties of normal barley starch (NBS) and waxy barley starch (WBS) granules from plants cultivated in a greenhouse under normal diurnal (16h light) or constant light photosynthetic conditions. Growth rings were observed in all starch samples regardless of lighting conditions. The size distribution of whole and debranched WBS analyzed by gel-permeation chromatography did not appear to be influenced by the different lighting regimes, however, a greater relative crystallinity measured by wide-angle X-ray scattering and greater crystalline quality as judged by differential scanning calorimetry was observed under the diurnal lighting regime. NBS cultivated under the diurnal photosynthetic lighting regime displayed lower amylose content (18.7%), and shorter amylose chains than its counterpart grown under constant light. Although the relative crystallinity of NBS was not influenced by lighting conditions, lower onset, peak, and completion gelatinization temperatures were observed in diurnally grown NBS compared to constant light conditions. It is concluded that normal barley starch is less influenced by the diurnal photosynthetic lighting regime than amylose-free barley starch suggesting a role of amylose to prevent structural disorder and increase starch granule robustness against environmental cues.
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108, USA.
authors.forename: Avi
authors.initials: A
authors.lastname: Goldstein
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108, USA.
authors.forename: George
authors.initials: G
authors.lastname: Annor
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108, USA.
authors.forename: Varatharajan
authors.initials: V
authors.lastname: Vamadevan
authors.affiliation: Department of Molecular and Cellular Biology, Summerlee Science Complex, University of Guelph, N1G2W1, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Tetlow
authors.affiliation: Niels Bohr Institute, University of Copenhagen,Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Jacob J K
authors.initials: JJ
authors.lastname: Kirkensgaard
authors.affiliation: Niels Bohr Institute, University of Copenhagen,Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Kell
authors.initials: K
authors.lastname: Mortensen
authors.affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Blennow
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Denmark.
authors.forename: Kim H
authors.initials: KH
authors.lastname: Hebelstrup
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St Paul, MN 55108, USA. Electronic address: eric.bertoft@abo.fi.
authors.forename: Eric
authors.initials: E
authors.lastname: Bertoft
mesh_terms: D002940:Circadian Rhythm / Q000528:radiation effects; D001467:Hordeum / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D008027:Light; D010788:Photosynthesis / Q000528:radiation effects; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D013213:Starch / Q000737:chemistry*; D013696:Temperature; D014885:Waxes / Q000737:chemistry*
chemical_list: D010940:Plant Proteins; D014885:Waxes; D013213:Starch
keywords: Barley; Diurnal activity; Starch granules; waxy starch