• Wild blue wonder: X-ray beam explores fo

    From ScienceDaily@1:317/3 to All on Thu Dec 2 21:30:36 2021
    Wild blue wonder: X-ray beam explores food color protein

    Date:
    December 2, 2021
    Source:
    Cornell University
    Summary:
    A natural food colorant called phycocyanin provides a fun, vivid
    blue in soft drinks, but it is unstable on grocery shelves. A
    synchrotron is helping to steady it.



    FULL STORY ==========================================================================
    In food products, the natural blues tend to be moody.


    ==========================================================================
    A fun food colorant with a scientific name -- phycocyanin -- provides
    a vivid blue pigment that food companies crave, but it can be unstable
    when placed in soft drinks and sport beverages, and then lose its hues
    under fluorescent light on grocery shelves.

    With the help of physics and the bright X-ray beams from Cornell
    University's synchrotron, Cornell food scientists have found the recipe
    for phycocyanin's unique behavior and they now have a chance to stabilize
    it, according to new research published Nov. 12 in the American Chemical Society's journal BioMacromolecules.

    "Phycocyanin has a vibrant blue color," said Alireza Abbaspourrad,
    assistant professor of food chemistry and ingredient technology in the
    College of Agriculture and Life Sciences. "However, if you want to put phycocyanin into acidified beverages, the blue color fades quickly due to thermal treatment." The research, "Tuning C-Phycocyanin Photoactivity
    via pH-Mediated Assembly- Disassembly," was authored by Ying Li, a
    doctoral student in food science; Richard Gillilan, staff scientist at
    the Macromolecular X-ray science at the Cornell High Energy Synchrotron
    Source; and Abbaspourrad.

    Most food companies seeking blues in their food use synthetic food dye, Abbaspourrad said. Phycocyanin is a natural and more nutritional protein derived from algae, which is the main ingredient in spirulina, mostly
    sold in powder form at health food stores. The food scientists wanted
    to understand its color properties and how it worked.

    Food science, meet physics. The researchers partnered with the
    Macromolecular Diffraction Facility of the Cornell High Energy Synchrotron Source (MacCHESS) and used Size-Exclusion Chromatography coupled to
    Small-Angle X-ray Scattering (SEC?SAXS) on a beamline.

    Phycocyanin was placed into a biological fluid and brought to the MacCHESS laboratory. There, intense beamline X-rays were channeled into tiny drops
    of the fluid. The small-angle X-ray scattering showed that as pH levels,
    the molecular strands changed into different shapes, folds and assemblies.

    "So as pH changes, the phycocyanin molecules form in different ways,"
    Li said.

    "If the pH goes up, the molecules come together and if the pH level goes
    down, the molecules disassemble.

    "As we changed the environmental stimulus for the phycocyanin, the
    molecules modulate their behavior in terms of how they interact with
    light," she said.

    "It's a relationship of the protein structure and the color
    stability." The acidity of the environment can essentially mediate an assembly-disassembly pathway, Abbaspourrad said. "Through the X-ray
    scattering we could see the proteins and see how their monomers are
    assembled together and how the oligomers disassemble," he said. "That's
    the root cause for how the blue color fades." This research was funded
    by U.S. Department of Agriculture (National Institute of Food and
    Agriculture), and CHESS is supported by the National Science Foundation,
    New York state, and the National Institutes of Health and its National Institute of General Medical Sciences.

    ========================================================================== Story Source: Materials provided by Cornell_University. Original written
    by Blaine Friedlander, courtesy of the Cornell Chronicle. Note: Content
    may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Ying Li, Richard Gillilan, Alireza Abbaspourrad. Tuning
    C-Phycocyanin
    Photoactivity via pH-Mediated
    Assembly-Disassembly. Biomacromolecules, 2021; DOI:
    10.1021/acs.biomac.1c01095 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/12/211202191152.htm

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