Shrimps are an endless source of nutrients such as proteins, omega-3 fatty acids, vitamins, and minerals. But the story doesn’t end there. Shrimp processing generates a significant amount of “waste” (heads, shells, and tails) that may pose environmental challenges. However, recent research suggests that this “waste” could be a hidden treasure trove of valuable antioxidants.
A recent scientific study has identified new antioxidant molecules for the first time, offering intriguing possibilities for both human health and the food industry.
The research, conducted by a team of scientists from Memorial University of Newfoundland, focused on Northern shrimp (Pandalus borealis) and the often-discarded shells and heads. Using advanced techniques such as chromatography and mass spectrometry, they investigated the hidden antioxidant potential of shrimp.
Turning trash into money: the power of shrimp byproducts
Traditionally, shrimp processing discards have not been fully utilized. While some are used as protein flours or sources of chitin, most remain underutilized.
Up to 50% of shrimp processing generates byproducts. These shells, though often discarded, hold immense potential. They are rich in proteins, minerals, and a fascinating compound called chitin, a basic component of valuable products like chitosan. Now, researchers are discovering another intriguing possibility: the presence of phenolic compounds with potent antioxidant properties, offering an opportunity to valorize shrimp processing waste.
The advantage of antioxidants: why phenolics matter
Phenolic compounds are natural antioxidants found in plants and, as this research suggests, potentially in shrimp! These antioxidants combat free radicals and unstable molecules that damage cells and contribute to various health issues. Including antioxidant-rich foods in your diet may help combat these harmful effects, potentially promoting overall well-being.
Shrimp: a source of unexplored antioxidants
Current research on shrimp antioxidants focuses on carotenoids, protein hydrolysates, and indolocarbazole-type compounds. This new study paves new paths by investigating, for the first time, the presence of phenolic compounds in Northern shrimp and their processing byproducts.
Ethanol: the champion extraction solvent
The study revealed that ethanol emerged as the most effective solvent for extracting these valuable antioxidants from shrimp byproducts, particularly shells, which showed higher levels of total phenolic content (TPC) and total carotenoid content (TCC). These extracts exhibited notable antioxidant activity, protecting a model system containing beta-carotene and linoleic acid from oxidation.
These extracts were further analyzed, revealing a fascinating quartet of compounds: two highly polar and two with lower polarity. These unique molecules were then isolated and purified using state-of-the-art reverse-phase HPLC, a testament to the researchers’ meticulous approach.
The research team didn’t stop there. They further purified these antioxidant extracts and isolated four distinct compounds for the first time. These compounds, never before seen in shrimp, belonged to a unique class known as heterocyclic phenolics.
Using a powerful technique called electrospray ionization mass spectrometry, scientists tentatively identified the structures of these new antioxidants. Two of these compounds were highly polar, while the other two exhibited lower polarity.
The heterocyclic phenolic compounds were never before seen in shrimp. The team tentatively identified them as 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl)quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)-7,8-dihydroquinoline, along with their isomers.
Utility: from shelf life to new applications
The presence of these previously unknown antioxidants offers intriguing possibilities. They could explain why shrimp exhibit such remarkable resistance to oxidation, contributing to their long-lasting freshness. Additionally, these findings could pave the way for the development of new food additives with potent antioxidant properties.
Furthermore, these antioxidants could offer health benefits when consumed, aligning with the growing interest in natural dietary antioxidants.
Dr. Fereidoon Shahidi, co-author of the study, emphasized the importance of these findings, stating, “The discovery of these unique heterocyclic phenolic compounds not only provides insights into the antioxidant properties of shrimp but also opens new avenues for the utilization of shrimp byproducts, aligning with sustainable practices and waste reduction in the fishing industry.”
The mystery of discoloration: a new angle
The study also suggests a potential role these antioxidants could play in shrimp discoloration, a common concern during processing and storage. Understanding this link could lead to better practices for maintaining the vibrant color of shrimp products, in addition to using pigments like astaxanthin.
The future of shrimp: a sustainable source of antioxidants
This innovative research not only expands our knowledge of shrimp’s nutritional value but also opens doors for the sustainable utilization of shrimp processing discards. Extracting valuable antioxidants from shells and heads could lead to the development of eco-friendly functional foods and nutraceuticals.
The study was funded by the Natural Science and Engineering Research Council (NSERC) of Canada.
Contact
Fereidoon Shahidi
Department of Biochemistry, Memorial University of Newfoundland, St. John’s, NL, A1C 5S7, Canada
Email: fshahidi@mun.ca
Reference (open access)
Onodenalore, A.C., Hossain, A., Banoub, J. et al. Unique heterocyclic phenolic compounds from shrimp (Pandalus borealis) and beyond. Food Prod Process and Nutr 6, 29 (2024). https://doi.org/10.1186/s43014-023-00215-3
