Rheological properties of kafirin and zein prolamins

Oxidation of commercial (α-type) zein with hydrogen peroxide improves its hydration and dramatically increases dough extensibility even below its glass transition temperature

“…The absence of polymerisation due to the treatments under non-reducing conditions can be attributed to the fact that commercial zein is lacking cysteine groups for substantial disulphide bonding. As also found in this present work, commercial zein is essentially α-zein (Oom et al, 2008) which contains only one near terminal end cysteine residue (Belton et al, 2006) and lacks the cysteine-rich γ-and β-zein sub-classes. The absence of visible induced polymerisation with SDS-PAGE under reducing conditions was probably due to the level of dityrosine cross-links being very low.…”

Functionality of the storage proteins in gluten-free cereals and pseudocereals in dough systems

“…With oats and pseudocereals, the storage proteins are presumably readily freed from the protein bodies during dough-making due to their aqueous soluble nature (Schoenlechner et al, 2008). Lawton (1992) in seminal research showed that commercial zein, which is essentially only α-zein (Lawton, 2002;Oom et al, 2008), formed a visco-elastic wheat flour-like dough when mixed with maize starch and the inclusion of dibutyl tartrate (as a plasticizer) at 25 o C and above, and at 35 o C in the absence of dibutyl tartrate. A visco-elastic dough could not be formed below 25 o C and viscoelasticity was lost if the doughs were cooled below 25 o C. These temperatures were shown to relate closely to the T g of zein as a function of moisture content.…”

“…Dough viscosity has been found to be the major factor affecting gas bubble structure formation (Berta et al, 2015). Oom et al (2008) showed that kafirin (comprising α-and γ-kafirin) plus starch in water mixtures would not form visco-elastic doughs, even at the elevated temperature of 55 o C and with addition of lactic acid as a plasticizer. However, a "dough" could be formed with kafirin by plasticizing kafirin (which had been hydrated in water) into a resin using oleic acid in a 2:1 ratio (kafirin:oleic acid).…”

“…However, the aggregated kafirin mass had very poor dough properties as it immediately became hard. The inclusion of 5% mercaptoethanol (as reducing agent) improved its properties somewhat, as the mass remained (Oom et al, 2008). Reproduced with the permission of the copyright holder.…”

Increasing the utilisation of sorghum, millets and pseudocereals: Developments in the science of their phenolic phytochemicals, biofortification and protein functionality

“…These effects may explain the observations of Schober and co-workers that ensuring that zein in the dough mixing process is above the glass transition temperature creates a system with a high viscoelasticity (Schober et al, 2008;Schober et al, 2011;Schober et al, 2010). Similarly it has been shown that mixing either zein or kafirin with plasticiser to form a dough-like resin results in a viscoelastic system (Oom et al, 2008).…”