Blue is rare in nature, it is not a color that abounds but it is there. There is a food coloring whose scientific name is phycocyanin and which serves as a bright blue pigment in high demand by food companies. The problem is their great instability when they are introduced in soft drinks and sports drinks, in addition to that they lose their hues under the fluorescent light on the supermarket shelves. Phycocyanin is a blue-green algae chromoprotein and has the important quality of being metal-free. Along with chlorophyll, it is a substance that absorbs light. Specifically orange and red light. It fluoresces around 700 nm.
With the help of physics and X-rays from the Cornell University synchrotron, a group of food scientists has found a way for phycocyanin to display more stable behavior. The research was recently published under the title Tuning C-Phycocyanin Photoactivity via pH-Mediated Assembly – Disassembly , on November 12 in American Chemical Society’s journal BioMacromolecules. It is signed by Ying Li, a food science PhD student, Richard Gillilan, Cornell High Energy Synchrotron Source Scientist and Staff, and Alireza Abbaspourrad.
” Phycocyanin has a vibrant blue color ,” says Alireza Abbaspourrad, assistant professor of food chemistry and ingredient technology at the College of Agriculture and Life Sciences. “However, if you want to put phycocyanin in acidified drinks, the blue color quickly fades due to heat treatment .”
Abbaspourrad further adds that most food companies looking for blues for their products use synthetic colorants . Phycocyanin is a natural protein that comes from algae, making it more nutritious. It is also the main ingredient in spirulina, a dietary supplement sold in powder or pill forms sold in health food stores and herbalists. Nothing new if we take into account that the Aztecs and other Mesoamerican peoples already took it in the 16th century.
The researchers partnered with the Cornell High Energy Synchrotron Sorce Macromolecular Diffraction Facility (MacCHESS) and used reduced angle X-ray scattering coupled size exclusion chromatography (SEC-SAXS) on a beamline. Size exclusion chromatography is an analytical technique that separates dissolved macromolecules by size based on their exclusion from columns filled with a porous gel. On the other hand, low angle X-ray scattering is an analytical technique that measures the scattered X-rays in a sample as a function of the scattering angle, these angles being very small, 0.1 to 5 degrees.
The phycocyanin was introduced into a biological fluid and brought to the MacCHESS. Intense X-ray beam lines were channeled there over small droplets of fluid. The small angle X-ray scattering technique showed that with different pH levels the molecular strands changed in shape, folds and assemblages .
“So as the pH changes, the phycocyanin molecules take on different shapes,” Li said. “If the pH goes up, the molecules come together and if the pH goes down, they separate.”
“As we change the environmental stimuli for phycocyanin , the molecules modulate their behavior in terms of how they interact with light, ” Li continued. “It is a relationship of the structure of the protein and the stability of the color.”
“Through X-ray scattering we were able to see the proteins and observe how their monomers assemble and oligomers disassemble,” Abbaspourrad said.
” It is the root cause of how the blue color fades .”
This research was funded by the United States Department of Agriculture (National Institute of Food and Agriculture), CHESS, which is supported by the New York State National Science Foundation and the Institutes of Health and the National Institute of General Medical Sciences.
Source: Wild blue wonder: X-ray beam explores food color protein, Cornell Chronicle.
At the end of October 2021, an interesting article by Professor Abbaspourrad came to light in the Proceedings of the National Academy of Sciences, under the title Mammalian sperm hyperactivation regulates navigation via physical boundaries and promotes pseudo-chemotaxis . However, the title of the press release in the Cornell Chronicle is much more illustrative: Sperm change swimming patterns to locate the egg . Yes, the sperm go from a symmetric to an asymmetric movement pattern in the vicinity of the egg. The symmetric is to provide a direction in a straight line and the asymmetric would be more circular movements. This behavior is called hyperarousal, and it allows the sperm to sweep across the area once they are close to the egg, giving you more options to find it. An influx of calcium ions into the fallopian tubes triggers hyperarousal and circular swimming. The next step will be to know how calcium ions enter the flagellum.
“By understanding what determines the navigation mechanism and the biophysical and biochemical signals for a sperm to reach the egg, we can use those signals to treat couples with infertility problems and thus select the best strategy for in vitro fertilization,” said Alireza. .
This therefore goes far beyond knowing how sperm move, as it also has profound implications for human IVF or dairy cow fertilization. Engineers could build robotic micronaders. The team recorded the sperm swimming in microfluidics. They tested compounds such as caffeine, which increased calcium levels in the cell cytoplasm and thus recorded hyperactivation.
” This state of activation has been shown to be necessary for fertilization ,” Abbaspourrad said.
