Industrial fish processing generates significant quantities of waste around the world, posing a risk to human health and the environment. It has been estimated that about two-thirds of the total amount of fish processed in industries is discarded as waste.
One of the promising ways for the industrial exploitation of industrial fish waste is the production of protein hydrolysates (FPH) which have a wide field of applications in different sectors, i.e., food industry, pharmaceutics, cosmetics and animal feed.
In this study, a protease enzyme was produced by Bacillus mojavensis FP2 and applied in the hydrolysis of industrial tuna waste. The hydrolysates obtained were tested for their antioxidant, antibacterial and anti-hyperglycemic activity. The hydrolysates were also characterized to determine their properties.
The protease produced showed a high enzymatic activity (105.94 ± 5.99 U/ml), which made it possible to achieve a high degree of hydrolysis (24.2 ± 1.69%) . Concerning antioxidant activity, a DPPH free radical scavenging activity of 96.9 ± 1.04% was achieved at a concentration of 10 mg/mL. Also, the protein hydrolysates from tuna waste presented a very high reducing power, ranging from 0.43 to 0.53 at 5 mg/ml.

Regarding antibacterial activity, the hydrolysates showed an inhibition of Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. The hydrolyates also showed anti-hyperglycemic power. The hydrolysates which showed an inhibition of α-amylase activity were F45, F60 and F90, with an inhibition percentage of 15.97 ± 6.45%, 69.96 ± 1.34% and 14.16 ± 2.82%, respectively.
Finally, the tuna waste protein hydrolysates yielded peptides which had excellent solubility over a wide pH range, and good emulsifying and foaming capacities.