Yellow Tainting of Flesh in Pangasius (Pangasianodon hypophthalmus): Origin of the Color and Procedures for Removal

Abstract

Pangasius ( Pangasianodon hypophthalmus ) is a commonly farmed fish in ponds in Bangladesh but its yellow flesh color creates a barrier for export. Here, we investigated if feed ingredients and environmental parameters might impact yellow tainting of the flesh. In experimental feeds, maize (a typical ingredient in commercial feeds) was replaced by soybean meal, and frequent exchange of pond water was introduced. Chemical analyses showed that the commercial feed was high in carotenoids (lutein, zeaxanthin and β -carotene; 18.8 mg/kg) as compared to the experimental feeds (≤1 mg carotenoids/kg). After feeding the fish commercial and experimental feeds for 9 months, the content of total carotenoids in the flesh was reduced by 48% to 64% and visual yellowness by up to 47% by the experimental feeds. Weekly or biweekly water exchange in combination with the experimental feeds further reduced the yellow coloration to 22% relative to fish given commercial feed and without water exchange. Our study demonstrates that pangasius with white flesh can be produced in Bangladesh by combining feeds low in pigments with frequent water exchange.