Thermal gelling properties and mechanism of porcine myofibrillar protein containing flaxseed gum at various pH values

High-pressure processing influences the conformation, water distribution, and gel properties of pork myofibrillar proteins containing Artemisia sphaerocephala Krasch gum

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Artemisia sphaerocephala Krasch gum could improve WHC and gel strength.

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HPP (≤200 MPa) induced high immobilized water proportion and a dense, uniform microstructure of MP-AG gels.

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HPP (>200 MPa) decreased surface hydrophobicity and storage modulus of MP-AG solutions.

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HPP (>200 MPa) increased particle size and amount of reactive sulfhydryl group of MP-AG solutions.

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The results have great potential for developing reduced-sodium meat products.

The effect of high-pressure processing (100–4 00 MPa) on conformation, water distribution, and gel characteristics of reduced-sodium (0.3 M NaCl) myofibrillar protein containing 0.15% Artemisia sphaerocephala Krasch gum (AG) was investigated. The addition of AG resulted in the increase of WHC, proportion of immobilized water, and gel strength. Then, the WHC, proportion of immobilized water, and gel strength peaked after 200 MPa treatment, attributed to increased solubilization and zeta potential of MP, decreased particle size of MP, exposure of intrinsic tryptophan residues and the partial transformation of α-helix into β-sheet in MP. Moreover, 300 and 400 MPa induced decreases in surface hydrophobicity, solubility and storage modulus, resulting in the formation of loose and disordered gel structures with attenuated WHC. These results suggest that application of moderate HPP (200 MPa) combined with AG could provide a novel approach to improve the WHC and gelation properties of reduced-sodium meat products.

Regulation mechanism of myofibrillar protein emulsification mode by adding psyllium (Plantago ovata) husk

Psyllium husk (PH) is an excellent source of dietary fiber with strong water-absorption and viscosity. This work systemically investigated the regulation mechanism of myofibrillar protein (MP) emulsification mode by adding psyllium husk as composite emulsifiers to prepare O/W emulsions. The results showed that the physical stability of emulsions was improved by adding PH (0.1%-0.8%). The results of contact angle, interfacial tension and confocal laser scanning microscopy (CLSM) indicated that the stability mechanism of emulsions was affected by the addition of PH. At a low PH addition (0.1%), the adsorption of MP at the oil-water interface was enhanced, thus forming an elastic interfacial film that improves the stability of emulsions. However, when the PH addition increased to 0.8%, excess addition of pH even hindered the interfacial adsorption of MP. Notably, the pseudoplasticity and viscosity of emulsions increased due to the addition of PH, thus inhibiting the migration and aggregation of droplets.

Effect of chickpea (Cicer arietinum L.) protein isolate on the heat-induced gelation properties of pork myofibrillar protein

BACKGROUND

Heat-induced composite gels were prepared with 30 mg mL^-1 pork myofibrillar protein (MP) and chickpea protein isolate (CPI) (0, 3, 6, 9, 12, and 15 g kg^-1 ) in 0.6 mol L^-1 NaCl, at pH 7.0. The gel strength, water-holding capacity, rheological properties, and microstructure of MP-CPI composite gels were investigated.

RESULTS

Chickpea protein isolate improved (P < 0.05) gel strength and water-holding capacity of the MP composite gels. The rheological properties of MP-CPI composite gels were improved significantly by the addition of CPI. Meanwhile, the effects of CPI on the storage modulus of composite gels were positively correlated with the increased addition of CPI. Furthermore, according to low-field nuclear magnetic resonance (LF-NMR) results, the addition of CPI reduced the relaxation time of the composite gels and the relaxation peak area of free water, indicating that CPI could improve the water-holding capacity of MP-CPI composite gels. The microstructure of MP-CPI composite gels presented smaller and more uniform pores, which means that more water could be retained.

CONCLUSION

The addition of chickpea protein isolate improved the gel strength, water-holding capacity, rheological properties, and microstructure of MP gels, indicating that CPI could be a potential protein additive to improve the microstructure, texture, and functional quality of meat products. © 2020 Society of Chemical Industry.

Effect of pH and heating conditions on the properties of Alaska pollock (Theragra chalcogramma) surimi gel fortified with fish oil

To improve the quality and functionality of emulsified surimi gels, the effect of pH and heating conditions on the properties of surimi gel fortified with fish oil was investigated. Results showed that pH conditions influenced the solubility and emulsifying properties of surimi proteins and that the gel properties were associated with the protein properties. Under direct heating, the highest gel strength was achieved at pH 8.0, in which condition the solubility was significantly higher than others. Higher emulsifying stability resulted in enhanced gel strength relative to that of the control group. However, the changes in the gel strength were not consistent under two-step heating. In addition, the expressible moisture and oil content were found to vary depending on the pH values under both heating conditions. The corresponding changes in expressible moisture and oil content could be attributed to the high protein solubility and emulsifying properties of surimi proteins. Analysis of the dynamic rheological properties of the resulting surimi paste revealed that the gelation properties varied depending on the pH conditions during the heating process. In addition, the temperatures of myosin cross-linking changed according to the structure of surimi proteins, which in turn varied depending on the pH conditions. PRACTICAL APPLICATIONS: To improve the functionality of surimi-based product, the fish oil was added to prepare surimi gel. pH and heating conditions play important roles in the gelation of fish proteins. Therefore, this study investigated the effect of combined pH and heating condition on the property of surimi gel fortified with fish oil. The emulsified surimi gel with fine texture was obtained at pH of 8-8.5; moreover, heating conditions (direct heating and two-step heating) also influenced texture of emulsified surimi gel. These results provide the evidence to produce the emulsified surimi-based product with the high gel strength, water- and oil-holding capacity.

Antioxidant Properties of Water-Soluble Gum from Flaxseed Hulls

Soluble flaxseed gum (SFG) was extracted from flax (Linum usitatissimum) hulls using hot water, and its functional groups and antioxidant properties were investigated using infrared spectroscopy and different antioxidant assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), reducing power capacity, and β-carotene bleaching inhibition assay), respectively. The antioxidant capacity of SFG showed interesting DPPH radical-scavenging capacity (IC₅₀ SFG = 2.5 mg·mL⁻¹), strong ABTS radical scavenging activity (% inhibition ABTS = 75.6% ± 2.6% at 40 mg·mL⁻¹), high reducing power capacity (RP_SFG = 5 mg·mL⁻¹), and potent β-carotene bleaching inhibition activity (IC₅₀ SFG = 10 mg·mL⁻¹). All of the obtained results demonstrate the promising potential use of SFG in numerous industrial applications, and a way to valorize flaxseed hulls.