Emprego de tecnologias limpas na obtenção de compostos bioativos em resíduos de pescado

Abstract

Millions of tons of fish are filleted every year. Of the fish used in this process, approximately 60% of the live weight ends up not being utilized, generating lower-value byproducts or being discarded. Hydrolysis reactions have been used as a means to repurpose these byproducts, allowing the extraction of compounds with modified technological properties such as solubility, emulsification capacity, foam formation, and viscosity, as well as delivering biological effects such as antioxidant, antihypertensive, anticarcinogenic, lipid profile-reducing, and neuroprotective properties. This study explored the exclusive use of ultrasound (US) at temperatures of 14°C to extract proteins from the dorsal spines of grass carp (Ctenopharyngodon idella) and salmon (Salmo salar). The dorsal spines of carp were treated with frequencies of 35 and 130 kHz for periods of 20, 30, or 40 minutes, resulting in two protein fractions: solid (TPS) and liquid (TPL). The US increased the yield compared to the non-sonicated fraction. TPL (35 kHz) showed a 16% reduction in total and free sulfhydryl levels and a 25% increase in hydrophobicity. The US induced changes in protein conformation and band intensity, especially between 25 and 100 kDa for TPL at 130 kHz and below 30 kDa for TPS at 35 kHz. The dorsal spines of salmon were treated at 25 and 35 kHz for 30 minutes at 14°C, resulting in three protein fractions: solid (SPF), liquid (LPF), and meat (MeatPF). Modifications in the intensity and pattern of protein bands were observed. Samples of the US-treated fractions showed inhibition of α-amylase and α-glucosidase enzymes and antioxidant effects, particularly in SPF and MeatPF, demonstrating that US has potential to be employed at low temperatures in the recovery of meat adhering to salmon spines. Each fraction obtained from the dorsal spines presented unique characteristics that allow them to be utilized in the development of new food formulations, aiming for both product and consumer benefits. This study demonstrated the effectiveness of US in the extraction and modification of certain properties of proteins from fish byproducts, facilitating their use in the development of innovative food products.