Gene-edited mushroom; Technology detects microorganisms; Robotic kitchen

USDA will not regulate gene-edited mushroom
The U.S. Dept. of Agriculture (USDA) has recently notified Yinong Yang, associate professor and plant pathologist at Penn State University, that it will not regulate his genetically modified white button mushrooms developed using CRISPR-Cas9 technology. Yang utilized CRISPR-Cas9 to reduce the production of an enzyme (i.e., polyphenol oxidase) that causes browning by 30%. The anti-browning trait reduces the formation of melanin (brown pigment), improving the appearance and shelf life of the mushroom and facilitating automated mechanical harvesting.

According to USDA, the gene-edited mushrooms are not subject to regulation because they do not contain any additional genetic material or foreign DNA from plant pests such as viruses or bacteria. However, the new mushroom variety may be subject to other regulatory authorities such as FDA or EPA.

Laser technology detects microorganisms in food
Researchers at Korea Advanced Institutes of Science and Technology have developed a nondestructive, noncontact, and rapid optical method for measuring living microorganisms in meat products using laser speckle decorrelation. To test their method, the researchers inoculated fresh chicken breasts with E. coli and B. cereus. They then applied laser speckle imaging to the samples. The laser beam was illuminated onto a sample, and scattered intensity images were captured with a CCD camera.

The laser beam’s reflected light from tissues without living microorganisms exhibits static speckle patterns. However, the presence of living microorganisms dynamically perturbs light paths in tissues, resulting in varying speckle patterns over time. Thus, measuring and analyzing the dynamic speckle intensity patterns from the meat samples enable the detection of living microorganisms.

Through various experimental validations, the researchers found that spontaneous bacterial activity causes strong decorrelation in laser speckle dynamics. Additionally, they demonstrated that the optical method can also be applicable to various bacterial strains and base media.

The method has several advantages. First, it is noncontact and noninvasive. Meats sealed with transparent plastic wraps can also be examined with the method. Second, the method can provide rapid assessment; live bacteria can be identified within a few seconds. Third, the technique is simple and cost-effective. Its simplicity offers application flexibility, ranging from a compact optical module in a home refrigerator to a laser system for a food manufacturing line.

Although the method can detect the presence of bacterial activity quickly, it cannot differentiate or identify specific pathogenic bacterial strains, such as Salmonella, Listeria, B. cereus, E. coli, and Campylobacter.

MIT students invent robotic kitchen
Massachusetts Institute of Technology (MIT) mechanical engineering students have won the $10,000 Lemelson-MIT “Eat it!” prize for their Spyce Kitchen, an automated restaurant system that actually serves students in an MIT dining hall. The 20-sq-ft invention incorporates a refrigerator, dishwasher, stovetop, and chef all-in-one, allowing it to cook and serve meals using fresh ingredients without human involvement. The student team believes Spyce Kitchen will revolutionize the fast food and fast casual industry by operating with extremely low overhead while serving high-quality, nutritious meals at fast food prices.

Eggshell nanoparticles improve bioplastic
Researchers at Tuskegee University are adding eggshell nanoparticles to bioplastic to improve the flexibility and strength of biodegradable packaging materials. “We’re breaking eggshells down into their most minute components and then infusing them into a special blend of bioplastics that we have developed,” says Vijaya K. Rangari, a professor at Tuskegee. “These nano-sized eggshell particles add strength to the material and make them far more flexible than other bioplastics on the market. We believe that these traits—along with its biodegradability in the soil—could make this eggshell bioplastic a very attractive alternative packaging material.”

To create the new packaging material, Rangari and his colleagues experimented with various plastic polymers. This led them to a mixture of 70% polybutyrate adipate terephthalate (PBAT), a petroleum polymer, and 30% polylactic acid (PLA), a polymer derived from corn starch. PBAT begins degrading as soon as three months after it’s buried in soil.

To enhance the flexibility of the material, the researchers chose eggshells because they are porous, lightweight, and mainly composed of calcium carbonate, which decomposes easily.

The shells were washed, ground up in polypropylene glycol, and then exposed to ultrasonic waves that broke the shell fragments down into nanoparticles more than 350,000 times smaller than the diameter of a human hair. Then, in a lab study, the researchers infused a small fraction of these nanoparticles, each shaped like a deck of cards, into the 70/30 mixture of PBAT and PLA. The researchers found that this addition made the mixture 700% more flexible than other bioplastic blends, enabling its application in retail packaging, grocery bags, and food containers—including egg cartons.

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