Don’t be selfish, save the shellfish! Shellfish are more useful than ever imagined

August 5, 2017 |

In Colorado, researchers are fighting nasty, deadly, stubborn bacteria with chitosan, a material derived from shellfish shells like lobsters, crabs, and shrimps. The new material helps prevent superbug bacteria biofilms from forming in about 85 percent of their lab testing.

Chitosan is also being used as an ingredient in biopolymers that form bioplastics and biodegradable packaging, but it’s use is going beyond consumer products and into a host of other new uses like biomedical research, cattle feed, and antibacterial surfaces.

Chitosan for food

Lobster, crab, shrimp and other shellfish are delightfully delicious, but some devourers may feel a twinge of guilt over the pile of shells discarded after consuming the scrumptious crustaceans. Fear no more – there are more and more uses every day for these creatures due to the chitosan hidden away in those shells often destined for landfills.

As reported in NUU in February, researchers in Brazil examined the impact of supplementing beef cattle feed with chitosan. The work evaluated whether adding variable levels of chitosan into the animals’ diets would affect “total apparent digestibility, ruminal fermentation, microbial protein synthesis, nitrogen utilization, and urea and creatine metabolism of grazing beef steers.” The results were favorable, with the researchers recommending 900 mg of chitosan per kilogram of concentrate for grazing steers. “Chitosan effects on [dry matter] intake are likely related to both greater impact of [crude protein] and higher [dry matter], [natural detergent fiber], and [crude protein] digestibility,” they said. The researchers also theorized that chitosan’s antibacterial activity stems from its positive charge. It binds to the negatively charged surfaces of bacteria, altering permeability and, ultimately, leading to cell death.

So not only are shellfish fun to eat for humans, but they are also quite healthy and valuable for cattle feed.

Chitosan for health

The recent Colorado State University research demonstrates the usefulness of chitosan for medical uses, but there are countless other examples over the last few months all over the world.

As reported in NUU in May, researchers in India determined a spray made from chitosan from crab shells and silver nanoparticles is effective at preventing the proliferation of malaria-carrying mosquitos. The spray, developed by researchers at Bharathiar University in Tamil Nadu and National Taiwan Ocean University, was sprayed over water reservoirs in Coimbatore. In addition to killing mosquito larvae and pupa effectively at low concentrations, it was also found to be safe for mosquito predators, like goldfishes. “This research highlighted that chitosan-fabricated silver nanoparticles are easy to produce, stable over time,” said Jiang-Shiou Hwang of the National Taiwan Ocean University. “Hence it can be employed at low dosages to strongly reduce populations of the malaria vector, the Anopheles sundaicus mosquito without detrimental effects on the predation of natural mosquito enemies, such as goldfishes,” Hwang said.

More news came from India in March, as reported in NUU, when Dr. Subhasmita Swain at SOA University developed a biomedical patch with chitosan that can coagulate blood flow in patients. Her cousin died due to excessive blood loss after an accident, leading this researcher to find a way to take advantage of chitosan and turmeric powder. Turmeric, something you may have in your spice cabinet, is known for its antibacterial and antibiotic properties. Swain found that turmeric works effectively with chitosan which is a strong but biodegradable polymer to form the biomaterial patch that aids patient blood coagulation within two minutes, resulting in less blood loss. Considering that injury and related blood loss is estimated to be the third leading cause of death in India by 2020 from the World Health Organization, this patch could save many lives.

As reported in NUU last November, Boston scientists at Harvard University Wyss Institute for Biologically Inspired Engineering found that the antimicrobial and biodegradable properties of chitosan can be used in the medical industry as a kind of glue to help repair tissue or to hold together medical device implants. The coolest part? Once it has done its job, it biodegrades and there is no trace of it left behind in the patient, like a Band-Aid that automatically dissolves once the wound is healed. It’s also similar to the bandages we know of in another way – testing on punctured human intestines and lungs showed the chitosan biomaterial was actually stronger than the native human tissue.

Let’s not forget about the researchers in Portugal who were using chitosan combined with nano-materials for bone regeneration and bone grafting, as reported in NUU last October. They are doing further research to answer questions like how it degrades and how a human body accepts or interacts with the biomaterial.

Chitosan for biopolymers and bioplastics

Chitosan is useful as cattle feed and is increasingly purposeful for biomedicine, but it also is a prized ingredient for producing biopolymers and bioplastics. As reported in NUU in April, researchers at the Moscow Institute of Physics and Technology developed a faster, environmentally friendly way to depolymerize chitin and chitosan into low molecular weight, water-soluble oligosaccharides. Their process involves degrading chitin and chitosan by electron-beam plasma in a specially designed reactor, which reduces the time it takes to produce water-soluble oligosaccharides from days to just minutes. Conventional production is a multi-step, lengthy process that involves chemical depolymerization at high temperatures with hydrogen peroxide, organic and inorganic acids, and other “aggressive agents.” that result in large volumes of industrial wastewater.

Chitosan can also solve Egypt’s trash problem, as reported in NUU in January. In the United Kingdom, University of Nottingham engineering professor Nicola Everitt turned discarded shrimp shells into biodegradable plastic bags. Everitt is specifically targeting the Egyptian market, as the country has a large quantity of shrimp shell waste but lacks effective waste disposal systems with only about 60% of the nation’s garbage collected. “It occurred to me that we could use Chitosan extracted from shrimp shells and make biodegradable packaging,” Everitt told The Week. “So at least if it was lying around at the side of the road it would eventually degrade.” The shells are first boiled in acid to remove calcium carbonate, and then boiled in an alkaline substance to remove protein leaving just the remaining material, chitosan, a natural polymer. They found that 15 shopping bags can be produced from about 2 pounds of shrimp waste. The team is now working on cutting down process time.

Save the shells!

Now that shellfish shells are capable of being used in so many applications including cattle feed, biomedical and health uses and biodegradable packaging and bioplastics, we are left with many questions. Can chitosan be commercialized and profitable? When will these innovative products containing chitosan be available on the market? How do we collect large volumes of shells?

While some shellfish waste can come directly from the fishing industry and fish processors, the challenge will be to collect enough discarded shells to continue expanding chitosan’s production and use. Now what we need is some serious investments from companies willing to take the research to the next level and bring it ashore, and perhaps a place to drop off cracked shells after chowing down on our shrimp dinner.

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