Formation of amyloid fibrils from ovalbumin under Ohmic heating

• Published in: Heliyon 2023-11, Vol.9 (11), p.e22061-e22061, Article e22061
• Main Authors: Joeres, Eike, Drusch, Stephan, Töpfl, Stefan, Juadjur, Andreas, Psathaki, Olympia Ekaterini, Heinz, Volker, Terjung, Nino
• Format: Article
• Language: English
• Subjects: Amyloid fibril formation; Cross-beta sheet structures; Field flow fractioning; Moderate electric fields; Protein aggregation; Thioflavin T
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2023.e22061

Ohmic heating (OH) is an alternative sustainable heating technology that has demonstrated its potential to modify protein structures and aggregates. Furthermore, certain protein aggregates, namely amyloid fibrils (AF), are associated with an enhanced protein functionality, such as gelation. This study evaluates how Ohmic heating (OH) influences the formation of AF structures from ovalbumin source under two electric field strength levels, 8.5 to 10.5 and 24.0–31.0 V/cm, respectively. Hence, AF aggregate formation was assessed over holding times ranging from 30 to 1200 sunder various environmental conditions (3.45 and 67.95 mM NaCl, 80, 85 and 90 °C, pH = 7). AF were formed under all conditions. SDS-PAGE revealed that OH had a higher tendency to preserve native ovalbumin molecules. Furthermore, Congo Red and Thioflavin T stainings indicated that OH reduces the amount of AF structures. This finding was supported by FTIR measurements, which showed OH samples to contain lower amounts of beta-sheets. Field flow fractioning revealed smaller-sized aggregates or aggregate clusters occurred after OH treatment. In contrast, prolonged holding time or higher treatment temperatures increased ThT fluorescence, beta-sheet structures and aggregate as well as cluster sizes. Ionic strength was found to dominate the effects of electric field strength under different environmental conditions. •The amount of amyloid fibril structures is decreased under Ohmic heating (OH).•Smaller sized ovalbumin aggregates are formed under OH.•OH leads to a decreased size of ovalbumin aggregate clusters.•Heating via OH decreases the amount of beta-sheet structures in ovalbumin aggregates.•Higher amounts of alpha-helical structures are preserved via OH.