Reduced Washing Cycle for Sustainable Mackerel (Rastrelliger kanagurta) Surimi Production: Evaluation of Bio-Physico-Chemical, Rheological, and Gel-Forming Properties

Abstract

Although dark muscle is currently the most important obstacle in marketing high-quality Indian mackerel (Rastrelliger kanagurta) surimi, reducing washing remains a challenge for long-term surimi production from this species. Herein, the impact of washing cycles (one (W1), two (W2), and three (W3) cycles) with a 1:3 mince to water ratio on the bio-physico-chemical properties, rheology, and gelling ability of mackerel surimi was evaluated. The yield, Ca2+-ATPase activity, TCA-soluble peptide, and myoglobin contents of surimi decreased as the number of washing cycles increased, while lipid removal, reactive SH content, and surface hydrophobicity of surimi increased. Surimi generated by W2 and W3 provided the same rheological patterns and Fourier-transform infrared spectroscopy (FTIR) spectra as unwashed mince, with the highest gel strength and whiteness, as well as the lowest expressible drip, thiobarbituric acid reactive substances (TBARS), and fishy odor. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated the presence of polymerized proteins stabilized by disulfide and other interactions. Using a scanning electron microscope, several concentrated dense areas and distributed pores generated by myofibrillar proteins gel networks were found. Surimi from W2 and W3 appeared to be of similar overall quality, however W2 had a larger yield. As a result of the evaluation of bio-physico-chemical, rheological, and gel-forming capabilities, as well as product yield, W2 may be the best option for producing high-quality surimi from Indian mackerel in a sustainable manner.

Recovery of Functional Proteins from Pig Brain Using pH-Shift Processes

“…Protein unfolding uncovers hydrophobic amino acids, affecting the protein’s surface HPB. However, a proper alteration in surface HPB was required for excellent protein functionality (e.g., gel-forming ability and surface activity) [ 22 ]. Depending on the balance between protein–water and protein–protein interactions, accessible hydrophobic residues might create connections and enhance the gel or aggregation network when heated [ 22 ].…”

“…The viscosity modulus (G”) represents the viscous behaviour of food ( Figure 2 b). The tan δ illustrates the distribution of viscosity relative to elasticity ( Figure 2 c) [ 22 , 28 ]. Figure 2 shows the dynamic viscoelastic behaviour of Acid-PPI and Alk-PPI as they transition from sol to gel at different temperatures.…”

“…G’ fell rapidly after that. The drop in G’ was caused by the α-helix coil transition, which enhanced protein fluidity while decreasing viscoelasticity [ 22 ]; this describes why G” reduced ( Figure 2 b). In addition, this could also be due to the fact that the hydrogen bond breaks off at elevated temperatures [ 30 ].…”

“…The HPB of PPI was determined using the approach of Somjid et al [ 22 ]. Two hundred microlitres of 1 mg/mL aqueous BPB was added to 1 mL of PPI solution in 20 mM phosphate buffer (pH 6) and thoroughly mixed.…”

“…The rheological properties of PPI with the same moisture content of 91.12% were determined using a Rheometer (HAAKE MARS 60, Thermo Fisher Scientific Inc, Yokohama, Japan) [ 22 ]. When the temperature was pushed from 10 to 90 °C at a rate of 2 °C/min, changes in rheological parameters such as elastic modulus (G’), viscous modulus (G”), and tan δ were measured.…”