Synergistic effects of alkaline and heat treatments on structural and functional properties of mung bean protein isolate: improving physicochemical stability of plant-based emulsions

Plant-based meat alternatives often require fat replacers to mimic the texture of traditional products. This study aimed to develop plant-based emulsion gels using mung bean protein isolate (MBPI) as a potential fat substitute. However, creating these gels via heat setting requires a high protein concentration, which demands modification of the MBPI structure to enhance emulsifying properties. This study investigated synergistic effects of alkaline treatment (0.3 or 3.5% Na2CO3) and heat treatments (40 or 70 degrees C) on the functional properties of MBPI at high protein levels, for potential application as a plant-based emulsion. The combined treatments reduced the zeta potential of protein suspensions from -9 to -19 mV and altered the protein conformation to form smaller particles (from 426 to 166 mu m) with increased beta-sheet content. These treatments improved dispersibility of 8% MBPI suspension (58 to 86%), emulsifying activity index (6.34-10.89 m2 g-1), and stability coefficient (43 to 96%). Notably, MBPI samples treated with 0.3% Na2CO3 at 40 and 70 degrees C exhibited excellent emulsifying properties, forming stable monolayers at the oil-water interface, likely due to the increased surface activity of MBPI. Increasing protein concentration to 11% facilitated heat-set gel formation; however, addition of 3.5%-Na2CO3 induced premature gelation, limiting its application in emulsions. At 0.3%-Na2CO3, increasing the protein content from 8% to 11% and the oil content from 10% to 30% further reduced emulsion droplet size, especially for MBPI treated with 0.3% Na2CO3 at 70 degrees C (MB-0.3%-70 degrees C) from 5.10 to 2.61 mu m, likely due to decreased coalescence. This treatment yielded superior MBPI-stabilised emulsion gels with enhanced penetration, fluid retention, and stability by possibly reducing protein aggregation. These findings demonstrate the potential of MBPI modified by combined addition of 0.3% Na2CO3 and heat treatment, particularly MB-0.3%-70 degrees C, as a promising ingredient for producing plant-based emulsions. Potential synergistic effects of 0.3% Na2CO3 and heat treatments on MBPI impacted the interfacial behaviour of MBPI by alteration of protein conformation and hydrophobic interactions, along with decreasing particle sizes. These treatments could enhance the protein's functional properties, enabling the development of stable plant-based emulsion gels as fat replacers. image