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Title: Evaluation of Acid and Alkaline Processing to Remove Muddy Off-Flavors in Channel Catfish (Ictalurus punctatus)

item VANN, D.
item BILBY, C.
item THOMAS, S.
item Schrader, Kevin

Submitted to: Journal of Aquatic Food Product Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2007
Publication Date: 8/15/2007
Citation: Mireles Dewitt, C., Kleinholz, C.W., Vann, D.G., Bilby, C.A., Thomas, S., Schrader, K. Evaluation of Acid and Alkaline Processing to Remove Muddy Off-Flavors in Channel Catfish (Ictalurus punctatus). Journal of Aquatic Food Product Technology. 16(2):77-90.

Interpretive Summary: The most common off-flavor problems in farm-raised channel catfish are "earthy" and "musty". A processing method that uses acid and base treatments was developed to help reduce the levels of the earthy and musty compounds in catfish flesh. This post-harvest processing approach may help catfish processors produce a high quality product from earthy/musty off-flavored catfish.

Technical Abstract: Conditions that optimize MIB and geosmin reduction by protein solubilization were evaluated in catfish. For both MIB and geosmin spiked fish, acid and alkaline treatments effectively (p<0.001) reduced off-flavor. Average MIB and geosmin levels for untreated, unprocessed fish were 1.396 and 1.992 ppb, respectively. Pooled centrifuge levels for treated fish were: 0.194 ppb MIB and 0.398 ppb geosmin using citric acid; 0.104 ppb MIB and 0.258 ppb geosmin using phosphoric acid; 0.143 ppb MIB and 0.543 ppb geosmin using acetic acid; and 0.0987 ppb MIB and 0.426 geosmin using alkaline (sodium hydroxide) conditions. Centrifugation did not significantly effect (p=0.999) off-flavor removal for MIB, however it did significantly effect (p=0.05) geosmin removal.