RESUMEN
The objective of this research was to improve the protein extraction processes of Rastrelliger kanagurta (Indian mackerel) to generate protein isolate with enhanced bio-physico-chemical properties and gel-forming ability. To achieve this, two novel approaches were designed that utilized an additional alkaline separation step and were compared to a conventional process: acid solubilization â alkaline solubilization â pI and acid solubilization â pI â alkaline solubilization. The novel extraction designs resulted in a lower lipid content, lipid oxidation, and TCA-soluble peptides, as well as improving the color and sensory features of the refined proteins, which corresponded to the lowest total heme pigments (p < 0.05). Furthermore, the protein isolate recovered with the modified processes showed significant changes in biochemical properties (decreases in Ca2+-ATPase activity/reactive sulfhydryl content and an increase in surface hydrophobicity) and dynamic rheological behavior. As a result, by altering the extraction procedure it was possible to obtain improved gel characteristics such as gel strength, color, expelled moisture, and improved gel microstructure. Moreover, this study demonstrated that the gel network was partly stabilized by disulfide bonds, according to SDS-PAGE. Overall, this study demonstrates that by optimizing protein extraction procedures a considerable improvement in quality can be achieved and that an additional alkaline extraction after isoelectric point precipitation results in the optimized gel-forming ability of mackerel proteins.
RESUMEN
This work comparatively investigated the effects of different levels (0, 1, 3, and 5%, w/w) of cricket protein powder (CP) and soy protein isolate (SPI) on the gel properties of mackerel surimi. Both SPI and CP enhanced the rheological properties of surimi pastes during heating, as indicated by the increase in G' and Gâ³ and the decrease in tan δ. With increasing SPI content, the proteolytic inhibition, gel properties, water-holding capacity, and textural profiles of surimi gel were markedly enhanced. Molecular driving-force results showed that SPI markedly promoted the hydrophobic interaction, while disulfide bonds were dominant in CP-added gel. However, the whiteness of surimi gels tended to decrease with the increased levels of both additives, in particular CP. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that SPI hindered the polymerization of myosin heavy chain while CP participated in the formation of non-disulfide covalent bonds with actin. Fourier transform infrared (FTIR) spectra indicated that CP and SPI did not influence the secondary structure of proteins in surimi. Scanning electron microscopy (SEM) demonstrated that CP or SPI induced the myofibrillar protein to form smoother and compact gel network structures. Overall acceptability of the mackerel surimi gel can be improved by the incorporation of 5% SPI while CP had a negative impact on several parameters. However, CP showed the remarkable ability to prevent the lipid oxidation of the gel after storage at 4 °C for 7 days. Overall, both SPI and CP demonstrated positive impacts on the gelling characteristics of mackerel surimi; however, SPI was more advantageous than CP in terms of the gel-strengthening effect and sensory qualities. This study offered a potential use for plant and insect proteins as functional and nutritional ingredients for the production of dark-fleshed fish surimi.
RESUMEN
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.
RESUMEN
A low gel-forming ability is needed to be encountered using the dark-fleshed fish as a raw material. Optimal washing process can be a principled way of improving the gelling properties because washing is the most important step for surimi production. This study aimed to investigate the effect of ultrasonic-assisted washing (UAW) on the biochemical properties and gel-forming ability of frigate mackerel (Auxis thazard) surimi. Unwashed mince and conventional washing (CW) with 3-cycle of water (10 min per cycle) were compared to UAW for 5 and 10 min per cycle. UAW tended to improve the lipid removal, reduce the TCA-soluble peptide, and increase the surface hydrophobicity of surimi, but it had no influence on the Ca2+-ATPase activity, reactive sulfhydryl content, haem protein content, and lipid oxidation. UAW for 5 min per cycle rendered the surimi with the highest gel strength, whiteness, and water holding capacity as well as a regular aggregated network. With this method, the washing time can be reduced to 50% compared to the CW. Therefore, UAW for 5 min per cycle was an alternative approach for the production of mackerel surimi.
RESUMEN
Effect of cold carbonated water (CW) washing on the biochemical properties and gel characteristics of mackerel surimi was evaluated. Three washing cycles were performed with different orders of washing medium including T1 (water, water and water), T2 (CW, water and water), T3 (CW, CW and water) and T4 (CW, CW and CW). The results showed that CW washing, especially T4, caused the decrease in pH, Ca2+-ATPase activity and surface hydrophobicity and led to the increase in reactive sulfhydryl content. Regardless of washing treatment, haem protein of surimi decreased significantly compared to unwashed mince. However, carbonated water did not improve haem protein removal. The highest lipid reduction was found in T1 and T2. Gels from all CW washing treatments had a comparable whiteness. Breaking force of CW surimi gel increased with increasing washing cycle (T2 < T3 < T4). Deformations of all surimi gels were not much different (~7 mm). Expressible drip increased with increasing CW washing cycle. Numbers of jointed spherical matrices were found in surimi gel microstructures. With increasing CW washing cycle, densely packed aggregates were formed. Therefore, CW washing with appropriate cycle can be used as an alternative means for mackerel surimi production.