Comparison of Methods for Lipid Extraction from clam Scapharca inaequivalvis

Clam Scapharca inaequivalvis is a bivalve mollusk of Indo-Pacific origin, currently living also in the Adriatic Sea. Despite its content of valuable nutrients,1 it is not much appreciated as food in Mediterranean area and thus fishermen must pick it out from the clam Camelea gallina.2 Some of its precious nutrients are polyunsaturated fatty acids (PUFA) having a well-known beneficial influence on the vascular system. Considering this mollusk as a possible source of PUFA, our study was aimed at evaluating the efficiency of several methods with respect to the extraction of total lipids and the individual classes of fatty acids (saturated, monounsaturated and polyunsaturated). Conventional methods as Folch, Bligh and Dyer, and Soxhlet extraction with different solvents were tested, but also accelerated solvent extraction (ASE) and the use of low toxicity-solvents were evaluated. The highest yield of total lipid extract was 7.0 % (duplicate averaged, in relation to dry sample), obtained using ASE with chloroform/methanol, followed by a washing step with water. The next-highest yield (6.1 %) was afforded by Folch method, while the lowest yields were afforded by extraction with hexane/2-propanol and by Soxhlet extraction with hexane (2.3 %). The estimated percent total fatty acids in the total lipid extract ranged from 19.6 % (Folch method) to 39.4 % (Soxhlet extraction with hexane). The estimated percent PUFA in the total fatty acids ranged from 10.8 % (Soxhlet with hexane) to 22.5 % (ASE with chloroform/methanol). References 1) Piretti, M.V.; Taioli, F.; Pagliuca, G. Comparative Biochemistry and Physiology 1987, 88B, 1201-1208. 2) Pierantozzi, C.; Zambuchini, B.; Giosia, L.; Faini, V.; D‘Angelo, N.; Spina, M.; Ventura, A.; Buttafoco, S.; Sturba, M.; Quagliarini, C. Progress in Nutrition 2005, 7, 1-9.