Viscera obtained from fish processing, in this particular case from rainbow trout Oncorhynchus mykissarco, will be used to obtain an intermediate product to be integrated in the formulation of bio-based fertilizers  (BBF). Enzymatic hydrolyzation of the viscera has been achieved to obtain a protein concentrate with a high percentage of free amino acids and a minimum amount of fat and sodium.
For this purpose, the enzymatic reaction variables such as: enzyme type, concentration, reaction time, pH and temperature have been optimized.

To obtain a good final product, it is essential to keep the viscera under the cold chain (+4°C) until processing, minimizing as much as possible the time until processing. This will avoid protein and fat degradation and the appearance of undesirable odors associated with the appearance of ammonia compounds or biogenic amines.

A previous degreasing of the raw material will be necessary to improve the enzymatic hydrolysis yield and to guarantee a protein concentrate with the lowest possible fat content. It is preferable to carry out this defatting operation by physical operations.

Fig 1: Minced viscera
Fig 2: Enzimatic Hydrolysis

Authors: Iñaki Aramburu, BARNA, SA
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