[Variations in macronutrients and nutritive value of the protein of canned tuna stored for 3 years after its preparation].

The composition in macronutrients and available lysine of canned tuna stored for three years at room temperature, was analyzed. Digestibility (DC), biological value (BV) and net protein utilization (NPU) were determined with Wistar rats tests. The results were then compared to those obtained three years ago, when the canned food was prepared with casein standard protein plus DL-methionine, in order to control any variation that might had occurred in animal behaviour. No variation was found, either in macronutrient composition or in digestibility. However, BV and NPU decreased significantly. Highly significant, and somewhat surprising, was the finding that the amount of available lysine, which had diminished as the can was prepared with respect to the amount found in raw tuna, increased during the storage period.