The carotenoid astaxanthin has been extracted from processed crawfish waste using a soy oil process. Analyses have included pigment quantitative analysis, effects of protease enzymes on pigment release, use of ethoxyquin as an antioxidant stabilizer agent, and studies of the ratio of added soybean oil to crawfish waste (v/w) for optimal extraction. Hydrolysis of crawfish waste with a commercial protease, Milezyme@ 8X resulted in a 58% increase in astaxanthin release. Maximal pigment extraction and oil recovery was obtained from a 1:l (v/w) ratio of oil to crawfish waste. The astaxanthin-enriched oil (60 mg/100g oil), obtained from a 1:lO (v/w) ratio, or 3:lO (v/w) after the second stage of extraction, has application for a variety of pigmentation purposes, notably in aquatic diets for salmonid fishes.

Power models were developed to demonstrate relationships between absorption maxima (kmax) and specific extinction coefficients (Ella°m) for the carotenoid astaxanthin and astacene in different oils and organic solventg An accurate and rapid determination of concentration of astaxanthin-enriched oil can be achieved by using the vl% value based on absorption maxima in the visible predicted ~ lcm light spectrum. Several vegetable or fish oils have been shown to be comparatively efficient in extracting astaxanthin pigment from crustacean waste in a pilot plant.

Astaxanthin-rich oil extract from Louisiana crawfish by-product imparted a salmon-red coloration to the flesh and integument of rainbow trout on a diet containing 45 mg astaxanthinlkg feed. Carotenoids deposited in fish flesh were stable (ca 90% retention) in air-packed samples at 1 -2°C. Oxygen-evacuated and COz-enriched packaging gave adverse color stability. Lowest pigment levels were in frozen samples, with 53% of the absorbed pigment degraded in 14 days. Visual color scores were consistent with quantitative pigment analyses (r = 0.77). Higher pigment contents were observed in airpacked (1 -2°C) samples, possibly due to astacene or other breakdown products of astaxanthin. Maximal TBA values were observed in air-packed (1 -2'C) samples. The effect of tissue enzyme homogenate on fading of trout flesh is discussed.

Acid ensilage treatment preserves crawfish heat‐processed waste under ambient temperature conditions with stabilization of the astaxanthin pigment present. Implementation of acid ensiling prior to pigment extraction increased concentration of the astaxanthin oil extract by 40–50%, and oil recovery by 10%. A twofold increase in free amino nitrogen, and a 70% reduction in exoskeleton calcium carbonate, were observed in crawfish silage (pH 4.2) from acid/enzymatic hydrolysis, compared with controls. A correlation was seen between solubilization of calcium carbonate and pigment release in relation to silage pH. The role of acid‐resistant proteolytic microorganisms in breakdown of carotenoprotein complex is discussed. Application of ensilage process for ultimate commercial production of astaxanthin‐enriched vegetable or fish oils from pigment rich crustacean wastes is postulated.