Low-Toxicity Solvents for the Extraction of Valuable Lipid Compounds from Octopus (Octopus vulgaris) Waste

Abstract

This study focused on the recovery of valuable lipid compounds from octopus (Octopus vulgaris) by-products. Extraction conditions of total lipids (TLs), phospholipids (PLs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were optimized by employing a Simplex-Lattice design; for it, different relative concentrations of three low-toxicity solvents (ethanol, acetone, and ethyl acetate) were considered. The optimization process was also addressed in reference to fatty acid (FA) ratios (total polyunsaturated FAs/total saturated FAs and total ω3 FAs/total ω6 FAs). The variance analysis of multiple regression data demonstrated that the quadratic model was significant (p < 0.05) for TL, PL, and DHA values and the ω3/ω6 ratio. As a result, the following optimized values were obtained: 113.8 g·kg−1 dry by-products (TLs), 217.3 g·kg−1 lipids (PLs), 22.55 g·100 g−1 total FAs (DHA), and 3.70 (ω3/ω6 ratio). According to the model developed, optimized values were shown to correspond to the following relative solvent concentrations (ethanol/acetone/ethyl acetate): 0.46/0.00/0.54, 0.93/0.07/0.00, 0.83/0.17/0.00, and 0.64/0.00/0.36, respectively. Comparison to yields obtained by the conventional chloroform/methanol method was carried out. A novel strategy based on the employment of low-toxicity solvents is proposed for the extraction of valuable lipid constituents from octopus waste. A different solvent ratio would be necessary according to the lipid compound concerned.

Marine Animal Co-Products—How Improving Their Use as Rich Sources of Health-Promoting Lipids Can Foster Sustainability

“…The processing of cephalopods, such as octopuses and squids, is also a source of waste and co-products, corresponding to non-edible or less savory parts. Octopus processing originates co-products that may represent 10-15% of total weight after the commercial scission of tentacles and heads [67]. In the case of squids, the mantel is the portion directed for commercial purposes, with the heads, skin, viscera, tails, and ink becoming the processing co-products that are commonly discarded [68][69][70][71].…”

“…In viscera fractions from cuttlefish (Sepia officinalis), consisting of the stomach, intestines, and pyloric caeca, the lipid content was reported to represent 4.0% (DW) [97]. In the common octopus (Octopus vulgaris), co-products were reported to display a lipid content of 13.7% DW [67].…”

“…Omega-3 fatty acids were reported to be major components of phospholipids, and substantial amounts of plasmalogens were also detected [70]. Phospholipids constituted 22.9% of total lipid content in the co-products of the common octopus (O. vulgaris) [67]. Interestingly, in other squid organs, namely the liver, the major lipid class were not phospholipids but rather triglycerides, as is the case for the arrow squid (Heterololigo bleekeri) (up to 63% of total lipids) [155], schoolmaster gonate squid (Berryteithis magister) (53%) [156], and Humboldt squid (D. gigas) (up to 27%) [157].…”

“…A summary of the beneficial health effects ascribed to the lipids present in marine animal co-products is presented in Figure 4. The lipid content in marine animal co-products, although not predominant, is still very substantial, especially, as described before, in certain fish and shellfish species (it can represent more than 25% of co-products of meagre (A. regius) [94], sea bass (D. labrax) [93,95], Chinook salmon (O. tshawytscha) [103], gilthead sea bream (S. aurata) [91,94], sardinelle (S. aurita) [97], salmon (S. salar) [93], or bluefin thuna (T. thynnus) [96]), crustaceans (it can amount to more than 10% DW in shrimp co-products of Argentine red shrimp (P. muelleri) [55] or whiteleg shrimp (P. vannamei) [132,133] and to more than 15% in some lobsters, namely Australian lobster (P. cygnus) [126] and Australian rock lobster (J. edwardsii) [127]) and mollusks (more than 10% in Patagonian squid (D. gahi) [68,150], Argentine shortfin squid (I. argentinus) [151], giant squid (D. gigas) [119], or common octopus (O. vulgaris) [67] co-products). Obviously, the higher the lipid content, the more justifiable it is to explore and take advantage of these co-product matrixes as possible sources of healthy lipids.…”

“…Concerning EPA, the processing co-products of P. borealis (21.1% EPA) [59] and the exoskeletons of southern king crab (L. santolla, 20.5%) [55] present the highest percentual EPA contents among crustaceans, as do the co-products of wild scallops (P. maximus, 20% [149]), Patagonian squid (D. gahi, 17.2% [150,153]), and pen shell scallops (P. rugosa, 17% [119]) among mollusks. As for DHA, the roe (and male gonads) of blue mackerel (S. australasicus [104]), shells and heads of Argentine red shrimp (P. muelleri [55]), and especially the co-products of mollusks, especially Patagonian squid (D. gahi [153]) and common octopus (O. vulgaris [67]), can contain over 20% of this particular omega-3 fatty acid. Another way to look at the benefits that lipids from marine animal co-products may entail has to do with the low n-6/n-3 fatty acid ratios consistently reported.…”