Browsing by Subject "Protein oxidation"

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  • Wang, Hang; Luo, Yongkang; Ertbjerg, Per (2017)
    Minced beef was stored for 8 days and myofibrillar protein (MP) was extracted to investigate the effect of oxygen concentration (0, 20, 40, 60, and 80%) in modified atmosphere packaging (MAP) on heat-induced gel properties. Compression force of gels was lower when prepared from beef packaged in 0% oxygen, intermediate in 20 to 60% oxygen and greater in 80% oxygen. Total water loss of gels prepared from beef packaged with oxygen (20-80%) was higher and rheology measurements presented higher G' and G '' values. Additionally, gels from beef packaged without oxygen exhibited higher J (t) values during creep and recovery tests, demonstrating that oxygen exposure of meat during storage in MAP affect MP in such a way that heat-induced protein gels alter their characteristics. Generally, storage with oxygen in MAP resulted in stronger and more elastic MP gels, which was observed already at a relative low oxygen concentration of 20%. (C) 2017 Elsevier Ltd. All rights reserved.
  • Gurbuz, Goker; Kauntola, Vilja; Diaz, Jose Martin Ramos; Jouppila, Kirsi; Heinonen, Marina (2018)
    Interactions of food proteins and lipids under oxidative conditions may lead to alterations in food texture as well as loss of nutritional and sensory quality. Oxidative and physical stability of oil-in-water emulsions stabilized with water-soluble proteins extracted from quinoa (Chenopodium quinoa) and amaranth (Amaranthus caudatus) was monitored in an oxidation study at 30 A degrees C for 7 days. Alkaline extraction of proteins from the flours followed by acid precipitation and freeze-drying was conducted and purified rapeseed oil was used to prepare emulsions via high-pressure microfluidizer. Protein-stabilized emulsions showed lower physical and oxidative stability compared to Tween(A (R)) 20-stabilized emulsions. Lipid oxidation volatile profiles of protein-stabilized emulsions indicated advanced oxidation. Comparison with the physically more stable emulsions stored at 6 A degrees C pointed to the role of co-oxidation between proteins and lipids in coalescence of oil droplets and increase in droplet size. Emulsions stabilized with amaranth proteins showed higher resistance to oxidation compared to quinoa protein containing emulsions.
  • Liu, Miao; Lampi, Anna-Maija; Ertbjerg, Per (2018)
    Abstract Lard from pork back fat was dry fractionated based on crystallization temperature, resulting in fractions with a ratio of saturated to unsaturated fatty acids of 1.10 and 0.61. Lean minced pork was mixed with the saturated and unsaturated fat fraction and stored in modified atmosphere (80% O2 and 20% CO2) at 5 °C for 2, 5, 7, 9, and 12 days under light to investigate the effect on oxidative stability of lipids and proteins. The saturated fat group developed higher TBARS values and lower levels of free thiol groups during storage, indicating that the unsaturated fat fraction in minced pork promoted increased oxidative stability of both lipids and proteins. A higher content of α-tocopherol in the unsaturated fat fraction suggests that the differences in oxidative stability is causatively linked to the balance between the fatty acid composition and content of antioxidants. The TBARS values and free thiol content were negatively correlated, suggesting a relationship between lipid and protein oxidation.