Amino acid, fatty acid, and mineral profiles of materials recovered from rainbow trout (Oncorhynchus mykiss) processing by-products using isoelectric solubilization/precipitation.
Protein, lipid, and insolubles (bones, skin, scales, fins, insoluble protein, and more) were recovered from rainbow trout processing by-products by means of isoelectric solubilization/precipitation at basic pH and acidic pH. Isoelectric solubilization/precipitation of the trout processing by-products resulted in the recovery of protein that was higher (P < 0.05) in essential amino acids (EAAs), non-EAAs, and total EAA/total AA ratio when compared to the processing by-products. Basic pH treatments yielded a higher (P < 0.05) content of EAAs than the acidic pH treatments. Nutritional quality of the recovered protein was high based on EAAs meeting the FAO/WHO/UNU recommendations for adults. The presence of omega-3 and omega-6 fatty acids (omega-3, omega-6 FAs) and the omega-3/omega-6 ratio in the recovered lipids were similar to the trout processing by-products, indicating that the pH treatments had no effect on these FAs. Ca and P contents of the processing by-products exceeded the recommended dietary allowances (RDA), but Fe and Mg did not. Basic pH treatments yielded protein with the lowest (P < 0.05) amount of minerals and the highest (P < 0.05) amount of Ca, P, and Mg in the insolubles when compared to acidic pH. The isoelectric solubilization/precipitation of the processing by-products effectively removed minerals from the recovered protein without removal of the bones, skin, scales, fins, and so on, prior to processing. The results indicated that isoelectric solubilization/precipitation, particularly at basic pH, permitted recovery of high-quality protein and lipids from fish processing by-products for human food uses; also, the recovered insolubles may be used in animal feeds as a source of minerals.
Chen
Y-C
YC
School of Nutrition, No. 110, Sec. 1, Jianguo N. Rd., Chung Shan Medical Univ., Taichung, Taiwan.
Tou
J C
JC
Jaczynski
J
J
D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D011232:Chemical Precipitation; D005227:Fatty Acids / Q000032:analysis*; D005396:Fish Products / Q000032:analysis*; D029941:Fish Proteins / Q000737:chemistry; D005511:Food Handling / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008903:Minerals / Q000032:analysis*; D009753:Nutritive Value; D017686:Oncorhynchus mykiss; D012995:Solubility
D000596:Amino Acids; D005227:Fatty Acids; D029941:Fish Proteins; D008903:Minerals