Production of biofertilizers from tuna cooking waters through membrane nanofiltration and enzymatic hydrolysis

Brine as side-stream is one of the main environmental problems in the wastewater generation in different food industry processes, as it is for the tuna canning sector. The treatment of brines is a universal challenge due to its operation complexity and cost issues. More than 70% of the tuna caught in the world is canned or otherwise prepared or preserved. Spain leads Europe’s production of canned seafood with more than 343,000 tonnes of product weight produced, valued at €1.5 billion. The Iberian country also produces 70% of the canned tuna processed in Europe. The ratio of spent brine used per unit of canned tuna is around 1-1.5 kg of brine/kg canned tuna. So that, the estimation for annual production of spent brine generation is around 300,000-500,000 tonnes. As the typical disposals of brine are discharges to the sea and is the management jointly with the rest of process side streams through wastewater treatment plants, and due to the high salinity, it causes, consequently, problems of inhibition in the effluent treatment, and poor performance in the final effluents. However, these brines are rich in valuable proteins.

On the other hand, fertilizer consumption in Europe increases annually by 3% to cover increasing agricultural demand. Most of the fertilisers used in Europe are imported, more than 3 million t are imported annually into the EU since 2015 (Fertilizers Europe, 2019). Several research studies have reported the benefits of protein hydrolysates as bio stimulants on the physiology of different plant crops (Colla G. et al. 2015). In this context, this study focuses on the concentration and desalting of the cooking brine of tuna and further enzymatic hydrolysis to produce free amino acids-based hydrolysate to be further used as an ingredient for the formulation of a new bio stimulant.