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- Amyloid fibril formation (1)
- Cross-beta sheet structures (1)
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- Fakultät AuL (2)
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 influence of moderate electric fields (MEF) on thermally induced gelation and network structures of patatin enriched potato protein (PPI) was investigated. PPI solutions with 9 wt% protein (pH 7) and 25 mM NaCl were heated from 25 to 65 °C via OH (3–24 V/cm) or conventional heating (COV) at various come-up (240 s and 1200 s) and holding times (30 s and 600 s). Self-standing gels were produced but less proteins denatured when heated via OH. Further, SDS-PAGE and GPC measurements revealed more native patatin remaining after OH treatment. Scanning electron microscopy showed OH gels to have more gap-like structures and frayed areas than COV treated gels which resulted in lower water holding capacity. On molecular scale, less hydrophobic interactions were measured within the protein network and FTIR trials showed the MEF to affect beta-sheet structures. OH gels further showed lower rigidity and higher flexibility, thus, gelling functionality was affected via OH.