Valorização de tilápia: obtenção de concentrado protéico e aplicação na produção de filmes

Abstract

The growth of aquaculture and fish consumption has been accompanied by an increase in the generation of by-products from industrial processing. These by-products, which include carcasses, trimmings, and unused fish fractions, as well as underutilized whole fish that do not meet commercial weight and size standards, represent an important source of biomolecules with high nutritional value, especially proteins. In this context, strategies for adding value to these materials have aroused interest, contributing to the full utilization of resources in the production chain and to the reduction of environmental impacts. Therefore, this study aimed to evaluate the potential of processing by-products and underutilized whole tilapia (Oreochromis niloticus) fish, as well as different extraction solutions (aqueous and saline), for obtaining proteins. The following were used as raw materials: mechanically separated meat (MSM) obtained from carcasses (C), a mixture of carcass and trimmings in a “V” shape (CV), as well as whole fish with skin and head (C/P) and whole fish without skin and head (S/P), all previously eviscerated. The raw materials were processed to obtain surimi through three successive washing cycles, followed by the addition of cryoprotectants (sucrose and polyphosphate). The four surimis obtained were characterized in terms of centesimal composition, pH, water activity, collagen, yield, and color. Subsequently, the proteins were recovered by solubilization at different pH values, in aqueous and saline media, followed by isoelectric precipitation, and protein solubility curves were determined. The precipitated proteins were characterized in terms of moisture, protein content, yield, and color. The recovered proteins were applied in the development of biodegradable films and in the production of powdered protein concentrates. The films were evaluated for their physical, mechanical, optical, structural, permeability, and biodegradability properties, while the protein powders were characterized in terms of chemical composition, yield, technological, techno-functional, and nutritional properties. The results demonstrated that the nature of the raw material influenced the characteristics of the surimi. The solubility curves showed typical behavior of muscle proteins as a function of pH and allowed the definition of the appropriate range for protein precipitation and recovery. In the biodegradable films, the origin of the raw material influenced the material's performance, with greater mechanical resistance observed in the C/P films, possibly associated with a higher collagen content, as well as affinity for water and rapid biodegradation in aqueous medium. For the protein concentrate powders, the extraction medium and raw materials influenced the characteristics of the recovered proteins, with higher yield and protein content observed in the extraction in aqueous solution. The concentrates showed the presence of essential amino acids, relevant technofunctional properties, and structural and color differences related to the extraction medium. Overall, the results demonstrate that tilapia by-products and underutilized fish are promising raw materials for protein recovery and valorization, contributing to the development of sustainable food ingredients and biomaterials, as well as reducing environmental impacts in the aquaculture chain.