Amino Acid, Fatty Acid, and Mineral Profiles of Materials Recovered from Rainbow Trout (Oncorhynchus mykiss) Processing By-Products Using Isoelectric Solubilization/Precipitation

Authors

  • Y.-C. Chen,

    1. Author Chen is with School of Nutrition, No. 110, Sec. 1, Jianguo N. Rd., Chung Shan Medical Univ., Taichung, Taiwan. Authors Tou and Jaczynski are with Animal and Nutritional Sciences, P.O. Box 6108, West Virginia Univ., Morgantown, WV 26505, U.S.A. Direct inquiries to author Jaczynski (E-mail: Jacek.Jaczynski@mail.wvu.edu).
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  • J.C. Tou,

    1. Author Chen is with School of Nutrition, No. 110, Sec. 1, Jianguo N. Rd., Chung Shan Medical Univ., Taichung, Taiwan. Authors Tou and Jaczynski are with Animal and Nutritional Sciences, P.O. Box 6108, West Virginia Univ., Morgantown, WV 26505, U.S.A. Direct inquiries to author Jaczynski (E-mail: Jacek.Jaczynski@mail.wvu.edu).
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  • J. Jaczynski

    1. Author Chen is with School of Nutrition, No. 110, Sec. 1, Jianguo N. Rd., Chung Shan Medical Univ., Taichung, Taiwan. Authors Tou and Jaczynski are with Animal and Nutritional Sciences, P.O. Box 6108, West Virginia Univ., Morgantown, WV 26505, U.S.A. Direct inquiries to author Jaczynski (E-mail: Jacek.Jaczynski@mail.wvu.edu).
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Abstract

ABSTRACT:  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 (ω-3, ω-6 FAs) and the ω-3/ω-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.

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