The crustacean processing industry leaves behind a sizable amount of waste—750,000 tons of crustacean shells in Europe and 1.5 million tons in Southeast Asia alone, two of the major aquaculture exporting regions, according to FAO data.
But as evidence builds for the waste’s potential of becoming a source of nutrients itself, researchers from the Institute of Food Science in Madrid, Spain, looked at the storage stability of astaxanthin esters, fatty acid profile, and α-tocopherol of lipid extract from shrimp (L. vannamei) waste for its potential applications as a food ingredient in a study published in Food Chemistry.
“Due to the interest and applications of the shrimp lipid extract obtained from cephalothoraxes and cuticles waste, [the] objective of the present one has been to study in deep the composition of such extract, with special emphasis on studying the astaxanthin molecular species, and also its stability when stored at room temperature,” they wrote.
Analyzing extracted lipids of shrimp waste
The researchers used ten kilograms of frozen L. vannamei shrimp provided by Angulas Aguinada Burgos, thawed at room temperature and peeled manually. “From every 100 g of shrimps, 55 g were muscle and 45 g were waste,” the researchers wrote.
Shrimp waste (cephalothorax, cuticles, tails, and pleopods) was homogenized to a particle size of 5 mm.
Lipids were extracted with ethyl acetate and stirred for 30 minutes at room temperature in darkness, before being filtered through filter paper. The researchers analyzed the lipid extract, which was described as having an “intense red color and a characteristic shrimp odor,” for carotenoids, fatty acid profile, α-tocopherol, and cholesterol. Overall astaxanthin content was difficult to characterize in a general way, the researchers said, because the content varied greatly depending on the source.
For the stability assessment, a sample of the lipid extract in ethyl acetate was transferred into 25 ml amber glass vials and dried under a nitrogen flow. The vials were stored at room temperature for 120 days.
On days 0, 10, 35, 50, and 120, the researchers performed multiple analyses for degradation rate: All-trans-astaxanthin, total astaxanthin monoesters, total astaxanthin diesters, fatty acid profile, cholesterol content, α-tocopherol content, and thiobarbituric acid reactive substances.
Carotenoid content, PUFA content, and shelf-stability
“A total of 18 astaxanthin derivatives, including all-trans-astaxanthin, two cis-astaxanthin isomers, 5 astaxanthin monoesters, and 10 astaxanthin diesters, were tentatively identified,” the researchers reported.
They also found saturated fatty acids and polyunsaturated fatty acids. “It is worth noting that, among monoesters, the DHA-astaxanthin one was by far the most abundant,” they wrote. “Among astaxanthin diesters, 3 contained EPA and the other 7 DHA, and it was especially interesting that the double EPA and DHA diesters were present.”
They found some degradation of PUFA during storage, but added “having in mind the storage conditions (presence of oxygen, room temperature, long storage period), the degradation of PUFAs can be considered low, and the resulting PUFA/SFA and ω-6/ω-3 PUFA fatty acid ratios are still good from a nutritional point of view.”
“The lipid extract obtained has interesting applications as a food ingredient, owing to the coloring capacity of astaxanthin and the presence of healthy components,” they added.
Source: Food Chemistry
Published online ahead of print, http://dx.doi.org/10.1016/j.foodchem.2016.08.016
Authors: J. Gómez-Estaca, M. M. Calvo, I. Álvarez-Acero, P. Montero, M.C. Gómez-Guillén