Maillard reaction between pea protein isolate and maltodextrin via wet-heating route for emulsion stabilisation

Pea protein isolate (PPI)-maltodextrin (MD) conjugates were prepared by using controlled Maillard reaction at 90 °C in the solution state (wet-heating route). The degree of conjugation between PPI and MD was measured in terms of evolved colour, UV absorbance, and molecular weight change. Results showed that the degree of Maillard reaction increased with the increase in pH and reaction time; however, the PPI-MD conjugation was optimised and was successfully controlled within the initial stage at pH 7.5 and 8.0 to avoid the formation of melanonids.

Highlights

• Pea protein isolate (PPI) was conjugated with maltodextrin via Maillard reaction.
• Wet-heating route was used, and the reaction was controlled within initial stage.
• Mild alkaline pH (7.5–8.0), reaction time of 5 h at 90 °C were found to be optimum.
• No advanced Maillard reaction products (AMRPs) were observed.
• Solubility and emulsifying properties of PPI were improved after conjugation.

The random coil content of PPI significantly increased upon conjugation with MD producing more flexible structure. The functional properties of PPI in terms of solubility, surface change (zeta-potential), and emulsifying properties of PPI were significantly improved after conjugation with MD. The highest solubility PPI-MD conjugates was observed at 5 h of reaction. The canola oil-in-water (O/W) emulsion stabilised by PPI-MD 5 h conjugate at 2% of emulsifier concentration and homogenised at 60 MPa for 3 passes had the highest physical stability when subjected to 25–60 °C. These findings indicate that Maillard reaction can be controlled in the initial stage via the wet-heating route and the resulting conjugates can be much effective emulsifiers than plant proteins.

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Material

Pea protein isolate (PPI, NUTRALYS® S85 XF) and maltodextrin (MD) with a dextrose equiveillance of 39 (GLUCIDEX® 39) were provided by Roquette Pty Ltd. (Lestrem, France). The PPI contained 84.17% protein (Kjeldahl method, N × 6.25), 6.96% moisture (AOAC Method No. 925.10), 4.46% ash (AOAC Method No. 923.03), and 1.8% lipid (AOAC Method N0. 920.85). Commercial canola oil was purchased from the local market (Coles Pty Ltd., Victoria, Australia). All chemicals including sodium chloride, sodium hydrate, sodium dodecyl sulfate (SDS), 2 × Laemmli buffer, β-mercaptoethanol, Tris, glycine, bromophenol blue, Coomassie Brilliant Blue R-250, and Bradford assay reagents were of analytical grade and were purchased from Sigma-Aldrich Pty Ltd. (NSW, Australia).

Zijia Zhang, Bo Wang, Benu Adhikari, Maillard reaction between pea protein isolate and maltodextrin via wet-heating route for emulsion stabilisation, Future Foods, Volume 6, 2022, 100193, ISSN 2666-8335,
https://doi.org/10.1016/j.fufo.2022.100193.