Developing thermally stable beverage emulsions using mildly fractionated
pea proteins
Abstract
The presence of insoluble components greatly minimizes the potential
application of pulse proteins in beverage emulsions. Therefore, pea
protein concentrate was mildly fractionated by aqueous centrifugation at
4,000g for 1 min to recover a soluble fraction (71% protein yield),
which was then used to develop 5% oil-in-water emulsions using a
high-pressure homogenizer. Emulsion stability was tested by heat
treatment (90°C, 30 min) in the presence of NaCl (0-1M) at pH 7.0 and
2.0. Stability increased upon adding salt at pH 7, while at pH 2,
proteins and droplets aggregated. Heat treatment led to extensive
aggregation at both pH values due to denaturation and aggregation of
proteins at the oil droplet surface, which was further worsened by salt.
To prevent thermal destabilization, the proteins were heat-treated at
75°C for 30 min for partial denaturation before emulsification under hot
conditions. The heat-treated protein-stabilized emulsions at pH 7 had
superior thermal stability at all salt concentrations without
aggregation. However, a similar improvement in stability was not
observed at pH 2. Pre-heating the soluble protein exposed the
hydrophobic patches, leading to better adsorption on the droplet
surface, which did not show additional aggregation upon further heating
the emulsions at pH 7. The heat-treated protein-stabilized emulsions
showed about a 44% drop in lipid digestibility compared to the original
emulsions. The proposed approach could be a valuable addition to the
utilization of pea proteins in developing beverage emulsions that could
withstand the heat treatment used during food processing.