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In order to investigate the effect of ultrasound on the structure and physical stability of chicken myofibrillar protein (MP) under low-salt conditions (0.15 mol/L NaCl), as well as the oxidizing effect of free radicals generated by ultrasound on MP, this study investigated the changes in the structure and oxidative properties of MP under low-salt conditions after ultrasound treatments (20 kHz, 450 W for 0, 3, 6, 9, and 12 min). The results showed that compared with the control group, the solubility, physical stability, and absolute ζ-potential of MP under low-salt conditions increased significantly (P < 0.05) with ultrasonic treatment time, whereas the turbidity and particle size decreased significantly (P < 0.05). The solubility was increased to 58.5% after 12 min of ultrasonic treatment. After ultrasonic treatment, the surface hydrophobicity and molecular flexibility were significantly increased, indicating that ultrasonic treatment caused the highly aggregated structure of myofibrillar protein to unfold and the internal hydrophobic groups to be exposed under low-salt conditions. After ultrasonic treatment for more than 6 min, the free sulfhydryl content of MP began to gradually decrease, whereas the content of disulfide bonds increased. After ultrasonic treatment for 12 min, the contents of free radicals, carbonyl groups and dimerized tyrosine (by 20.55%) were significantly increased (P < 0.05), while the free amino group content was decreased significantly (P < 0.05). In conclusion, ultrasonic treatment changed the structural properties of MP under low-salt conditions and increased its physical stability, thereby contributing to the formation of emulsions. Ultrasonic treatment can generate free radicals; ultrasonic treatment time for 6 min can exacerbate the oxidation of MP. So, attention should be paid to the oxidizing effect of free radicals generated by ultrasound on MP when applying ultrasonic treatment to improve the functional properties of MP.

Emulsions prepared using myofibrillar protein (MP) as an emulsifier have poor stability under low NaCl condition. The effect of high-intensity ultrasound (HIU) treatment (frequency of 20 kHz, and power of 450 W) for different periods of time (0, 3, 6, 9, and 12 min) on the emulsifying properties of chicken MP under low NaCl condition (0.15 mol/L NaCl) and the stability and rheological properties of MP emulsions were investigated. The results showed that compared with the control group, the emulsifying activity index (EAI) and emulsion stability index (ESI) of MP significantly increased with increasing ultrasonic treatment time (P < 0.05). The Turbiscan stability index (TSI) and particle size of MP emulsions decreased significantly with increasing ultrasonication time, and the absolute value of the zeta potential significantly increased (P < 0.05). The rheological analysis showed that ultrasound treatment significantly improved the viscoelasticity of MP emulsions. The oil-water interfacial tension analysis showed that ultrasound treatment effectively enhanced the mobility of MP, and rapidly decreased the interfacial tension. Meanwhile, ultrasound treatment significantly increased the amount of adsorbed protein in MP emulsions (P < 0.05), indicating that ultrasound treated MP contributed to emulsion stability. As observed by cold-field scanning electron microscopy, the emulsion prepared with MP treated by ultrasound for 12 min had the smallest droplet size. In conclusion, ultrasound treatment can significantly improve the emulsion stability of MP under low NaCl condition, which provides a theoretical reference for the application of ultrasound treatment to reduced-salt emulsified meat products.

As in many cities, utilitarian cycling is part of Toronto's climate strategy. For this tactic to work, cycling must occur throughout the city, yet despite most of the city's suitable short trips (60%) occurring in the suburbs, suburban residents cycle far less for transport than downtown residents where most cycling infrastructure is found. Nonetheless, some people in suburban areas cycle for transport, but little research focuses on suburban cycling. This has important implications for health, climate and equity. We used generalized structural equation modeling to analyze data from a survey of factors influencing utilitarian and recreational cycling among residents of a lower-income auto-oriented suburb lacking utilitarian cycling infrastructure (n = 215). Principal component analysis was used to develop latent attitudinal variables. The strongest predictors of utilitarian cycling were the frequency of recreational cycling, bike ownership, knowing people who bike, being male, and owning fewer cars. The strongest predictors of recreational cycling were bicycle ownership, knowing people who bike, knowing where to access repairs, and having attitudes strongly related to health and safety. Utilitarian cycling did not influence the frequency of recreational cycling. None of the latent attitudinal variables influenced utilitarian cycling. However, respondents scoring high in the expense and theft variable were more likely to live in lower income households. Those in higher income households scored higher on the health and safety variable. Results suggest group rides, access to bicycles and repairs, and ways to meet people who bike may be useful interventions to increase utilitarian cycling in suburban communities. [ABSTRACT FROM AUTHOR]