The impact of typical primary or secondary lipid oxidation (LPO) products, selected as linoleic acid 13-hydroperoxide (13-HPODE) and malondialdehyde (MDA), on the structural modification of unadsorbed or adsorbed proteins in whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions during storage up to 48 h at 37 °C in the dark was investigated. The results showed that either 13-HPODE and MDA could lead to structural modifications of unadsorbed or adsorbed proteins with a concentration-dependent manner and time relationship, respectively. Moreover, higher levels of MDA rendered a higher degree of oxidative modifications of WPI than 13-HPODE, indicated by the higher protein carbonyl contents and N’-formyl-L-kynurenine (NFK) and lower fluorescence intensity. Additionally, adsorbed proteins were more easily oxidized by LPO products than unadsorbed proteins. Overall, our results indicated that the formation of secondary LPO products and the protein position were crucial factors to increase the degree of oxidative modifications of WPI in O/W emulsion systems.
Myofibrillar protein microgel particles (MMP) are promising Pickering stabilisers due to their structure and delivery potential. However, their fibrous, irregular shape promotes aggregation, limiting practical use. This study investigated the effect of xanthan gum (XG) concentration (0.025–0.4%) on MMP dispersion in water and its role in stabilising Pickering emulsions. FTIR and interaction analysis revealed that hydrophobic interactions dominate between XG and MMP, followed by hydrogen bonding and electrostatic forces. At higher XG concentrations (0.2–0.4%), complex particle size decreased from 5.21 μm to 4.49 μm, the contact angle increased from 57.67° to 77.33°, and a uniform dispersed state was achieved. Although increasing XG gradually reduced the emulsifying activity of MMP, it significantly improved the emulsion stability. Microstructure analysis showed that at low XG concentrations, emulsions exhibited phase separation. Rheological measurements indicated that XG-MMP complexes increased continuous-phase viscosity and shear resistance, enhancing macroscopic stability. In summary, at a critical XG concentration of 0.2%, the emulsion undergoes a transition from aggregation-driven instability to network-mediated stabilisation, achieved through the interfacial layer with spatial confinement by a weak aqueous-phase network. This work provides a theoretical foundation and a practical design strategy for fabricating highly stable, tuneable Pickering emulsions based on protein microgel particles.
This study evaluated the impact of a low-phosphate water-holding system on the quality attributes of pork patties subjected to repeated freeze-thaw (F-T) cycles. The experimental formulations included: a control group (without water-retaining agents), a full-phosphate group (FP), low-phosphate group I and II (LP-I, LP-II). Results demonstrated that LP-II effectively maintained a higher pH value within the system and significantly inhibited moisture migration. After the seven F-T cycles, the thawing loss and cooking loss of LP-II group were reduced by approximately 12% and 15% respectively compared to the control. Concurrently, the LP-II group exhibited better microstructure and protein secondary structures. LP-II demonstrated efficacy in better sensory properties such as appearance and flavour following F-T cycles. Therefore, our findings show that while reducing phosphate usage by 50%, LP-II achieved comparable or even superior performance to the full-phosphate formulation in key indicators such as water retention and texture.