Characterization of the influence of pirarucu age and weight on their physicochemical composition

•The physicochemical characteristics differed in the different ages and weights.•There is only a high correlation between fatty acid profile and age.•Consuming Arapaima provides health benefits, although it is not a source of EPA+DHA.•Colorimetric parameters varied according to the analyzed region, age, and weight.•Twenty-four-month-old animals weighing at least 10 kg are indicated as raw material. This study aimed to evaluate the influence of age and weight on the physicochemical characteristics of captive-bred pirarucu blankets. Four harvest operations were conduced in two tanks; five specimens were obtained per harvest per tank, and the animals were 18, 24, 25, and 30 months old. The animals were slaughtered and processed in a local slaughterhouse, and the blankets cut were characterized in terms of proximate composition, instrumental color, fatty acid profile, and lipid nutritional quality indices. The data analyzed for proximate composition were higher at younger ages, whereas the peak occurred at 25 months for lipid content (2.19 %). The major fatty acids were C18:1n-9cis (33.53–36.72 %), C16:0 (22.79–26.01 %), C18:2n-6cis (18.25–19.52 %), and C18:0 (10.65–14.62 %), and the fatty acid profile decreased the older the animals were except for C17:0, C18:0, C20:1n-9cis, saturated fatty acids, and thrombogenicity index. The physicochemical characteristics differed in the different ages and weights. Moreover, there was only a high correlation between fatty acid profile and age. It was possible to conclude that the age of 24 months with live weight of ∼ 10 kg was the most suitable given this was the change threshold observed in this study.