Chemical and nutritional quality of Indonesian dried‐salted mackerel (Rastrelliger kanagurta)

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Abstract
Summary: Indonesian mackerel (Rastrelliger kanagurta) were sun dried or salted and sun dried and stored at 30°C for up to 20 weeks in air. During processing and storage polyunsaturated fatty acids oxidized to form thiobarbituric acid (TBA) reactive substances and fluorescent compounds. TBA values increased with increasing salt content (range 2.3–20.7%). Positive, highly significant correlations were found between the odour of the stored products and both fluorescent pigment production and the degree of browning. Amino acid analysis indicated loss of lysine, glutamic acid, serine, histidine, arginine and the sulphur containing amino acids, but these losses were far too small to account for the massive decreases found in net protein utilization (NPU) of the stored products, measured by rat‐feeding trials. The latter were highly correlated with the fluorescent pigment content and degree of browning in products of intermediate (∼ 14%) salt content.