Chemical composition and antioxidant properties of Philippine oyster (Crassostrea iredalei) residue


by:Ernestina M. Peralta, Karmelie Jane M. Monaya, Rhoda Mae C. Simora and Augusto E. Serrano, Jr.


This study evaluated the oyster residue, a by-product of oyster extract processing in terms of chemical components (proximate, total amino acid, chemical score), physical properties and its antioxidant activities (free radical scavenging activity, reducing power, and Gallic acid equivalents).The extraction process involves homogenization with water, mild heat treatment and filtration steps. The resulting residue was dried and pulverized. Analyses revealed that the product contain 73.89 + 0.40% protein, 8.92 + 0.12 % lipid, 8.65 + 0.02% ash, and 3.98 + 0.05 % moisture with an Aw of 0.24. Amino acid profile (g/100g crude protein) shows that the product contains the nine essential amino acids, having lysine (6.26g) and leucine (6.15g) as the major components. Evaluation of the chemical score (CS) of the residue showed that tryptophan (59.6) was the limiting amino acid. Essential amino acid index (EAAI) of 94.9 indicates that the EAA balance of the residue is well balanced despite being deficient in tryptophan (Trp). Antioxidant activities significantly increased with increasing sample concentration, suggesting the potency of bioactive compounds responsible for its antioxidant capabilities. Results of the study shows that oyster residue can be a good source of dietary protein and bioactive compounds.

Keywords: oyster residue, essential amino acids, antioxidant activity