Valorization of Shrimp By-Products (Pleoticus muelleri): Influence of Blanching and Grinding on the Extraction of Carotenoids and Fatty Acids

Introduction: The peeling of the Argentinian shrimp, Pleoticus muelleri, generates substantial by-products that are an underutilized source of high-value compounds such as astaxanthin and omega-3 fatty acids (EPA and DHA). This study evaluated the effects of blanching and particle-size reduction on the extraction efficiency of carotenoids and lipids, aiming to support sustainable valorization of shrimp processing residues.

Methods: Heads, shells and tails from shrimp peeling were blanched (70 °C , 3 min, 1:25 biomass/water) in freshwater or seawater. After grinding in a Retsch ZM 200 mill at 8000 rpm using 10, 3, 1 and 0.5 mm screens, lipids were extracted with 96% ethanol (25 °C, three successive extraction steps). Carotenoids were determined spectrophotometrically at 444 nm (Whyte, 1987), and fatty acids by direct transesterification (Lepage & Roy, 1984) using C19:0 as internal standard, followed by gas chromatography. 

Results: Reducing particle size to 10 mm provided carotenoid recovery comparable to finer grinding while significantly reducing energy requirements, making it more suitable for industrial implementation. Freshwater blanching produced higher recoveries of both total fatty acids (8.1 ± 0.4 g/100 g dry by-products) and carotenoids (175 ± 2 mg/100 g dry by-products) than seawater blanching (6.2 ± 0.3 g and 122 ± 2 mg/100 g, respectively). Although seawater reduced overall extraction yields, it increased the relative proportion of DHA while decreasing EPA and arachidonic acid.

Conclusions: Freshwater blanching combined with moderate grinding offers the best compromise between extraction efficiency and industrial feasibility, while seawater blanching may be preferable for DHA-enriched extracts. Although seawater lowers extraction yield, it requires less potable water at a water-intensive stage, and explicit sustainability criteria are needed to guide this choice. These findings support scalable biorefinery approaches potentially turning a currently landfilled residue into a regional feedstock for aquaculture nutrition.