Dr. Carmen Gomes is a gifted faculty member here at Texas A&M University’s Biological and Agricultural Engineering department. She is an associate professor and her research applies nanotechnology to improve food safety. Dr. Gomes started her journey at Texas A&M as an undergraduate visiting scholar from Brazil through a Fulbright fellowship and had the opportunity to work under Dr. Rosana Moreira in her food processing laboratory. After her fellowship ended and Dr. Gomes returned to Brazil to finish her degree in Food Engineering, Dr. Moreira, Professor of Biological and Agricultural Engineering, recruited her as a PhD student. Dr. Gomes’ dissertation research was primarily on irradiation-processing of food products in which electron beams were used to reduce or eliminate microbial presence, and consequently to prevent food poisoning and extend shelf-life. It was during this period that she was first introduced to nanotechnology in food processing applications and the use of polymers.

Upon graduating, Dr. Gomes accepted a faculty position in the Biological and Agricultural Engineering department. She began collaboration with faculty at A&M and other universities, to further explore nanotechnology in food applications, primarily, through the use of polymeric encapsulation. Polymers are nano-sized and can be capsules, gels, networks, fibers, or nanobrushes which are microscopic, hair-like structures that allow for movement. These polymers use encapsulation to control the release of natural antimicrobials to combat dangerous foodborne bacteria, such as Listeria, Escherichia coli, and Salmonella species.

When used to control bacterial growth, the polymers work to contain and protect targeted materials, as well as provide controlled release and microorganism capture. One study by Dr. Gomes examined the effectiveness of guabiroba fruit, a natural product with antioxidant and antimicrobial activity, which inhibits the growth of the bacteria Listeria innocua. While Listeria innocua is not pathogenic, it serves as a research substitute for its dangerous relative, Listeria monocytogenes, which can cause anything from mild flu like symptoms to convulsions, miscarriages, septic shock, meningitis and encephalitis, and even death.  By encapsulating the guabiroba in nano-polymers, bacterial growth was reduced up to 6-fold.  The use of this technology commercially could significantly improve the safety of foods such as soft cheeses, celery, sprouts, cantaloupe, and ice cream, sources of food-borne illness for 1,600 people in the US annually.  Work continues to perfect this technique, though the projected commercial use may take several years to decades.

Concurrently, Dr. Gomes is studying the capabilities of nanobrush polymers to act as biosensors. These nanobrushes are biomimetic, meaning that they mimic models already found in nature, such as the one in the Hawaiian bobtail squid. This particular squid draws Vibrio fischeri bacteria to itself as a means of self-preservation by using the illuminating fluorescence of the bacteria to deter the squid’s predators at night. Ciliated appendages, also known as a “brush border”, on the internal light organ of the bobtail squid facilitate colonization by the bacteria through a combination of molecular receptors along the cilia and also the cilia movement. During the day the squid becomes inactive and no longer needs the bacteria’s protection, expelling the bacteria from itself.

Just as in the squid model, polymers are being developed with sensors that are stimuli-sensitive. Dr. Gomes, with help from her colleagues, has developed a bacteria-sensitive nanobrush that recognizes Listeria species as it comes into contact with the nanobrush and captures the bacteria. Compared to the typically-used Polymerase Chain Reaction (PCR) testing to detect Listeria species, this new technique is incredibly useful. Unlike PCR testing, which is expensive, labor and time intensive, and requires highly skilled individuals to conduct, this method provides almost instantaneously means of detecting pathogens. In addition to being a much more rapid process, this technique will make laboratory reliance obsolete as well as increase user friendliness among laypeople. Using this technology, food processing plants will be able to utilize biosensors in multi-point inspections to alert personnel of contamination. By continuous screening in both food contact zones and non-food contact zones, such as pipelines, and catching the contaminants before food reaches the end of processing and becomes available commercially, food-borne outbreaks can be prevented. These biosensors are projected to be implemented in processing plants in the next 5 years.

With each study, selection of polymers must meet several requirements.  In both cases, the polymer must be cost efficient and be widely available while responding appropriately to stimuli and satisfying the delivery system’s conditions in its intended target. Depending on its intended function, it must respond to the appropriate temperature and pH levels, be stable in its intended environment, and have the capability to shrink, collapse, and release. Additionally, when used to inhibit microbial growth, the polymers must be allergen free, biodegradable, be small enough to not affect visual inspection by the consumer, and not change the taste and texture of the food being consumed. With all these restraints in mind, coming up with specific, successful polymers to tackle each emerging obstacle, is quite a challenge. With the help of exceptional students in her research group, Dr. Gomes is making great strides in providing expanding solutions to an ever increasingly important topic in the food industry.

Article by Whitney Steinmann

For details about this news story and others please contact Stormy Kretzschmar, stormyk@tamu.edu.