## 4 Discussion  
The physicochemical and functional properties of vegetable proteins determine their application in the food industry. The pH of the samples was between 6.83 and 7.66. [PERSON] [29] mentions that the relationship between pH and solubility of a protein depends on the prevailing charge on the amino acids at various pH values and that the balance of charges (+,-) reduces electrostatic repulsion and thus the solubility. On the other hand, [PERSON] et al. [30] reported that the hydrophobicity of the surface of a protein is a good indicator of the foaming and emulsifying capacity. Electrical conductivity, also related to protein charge, was higher in SMI and SMH proteins than their soy analogs. [PERSON] et al. [31] reported a conductivity of 2.70 mS/cm for commercial SI (500E), consistent with the results obtained herein related to SI and SH of 2.48 and 2.24 mS/cm, respectively. In the food industry, the EC of a protein is crucial because it determines its stability in different food systems, such as beverages [32]. Additionally, EC in emerging processes such as pulsed electric fields affects the performance of the protein during treatments. The soybean and soybean-maize samples had similar protein contents: 93% and 76% for isolates and hydrolyses, respectively. However, their protein composition was different because the maize germ contained 18.4% protein, containing 30% albumin, 30% globulins, 25% glutelins, and 5% zein (db), respectively [6]. On the other hand, soybean contains approximately 50% protein, with 90% as globulins [13]. The fat content for all samples was around 0.55% except for the commercial soybean isolate, which only contained 0.09%. This result is in agreement with fat values reported by [PERSON], [33], for soybean flour (0.55%), concentrate (0.30%), and isolate (<0.01%). peptides' size or molecular weights. FAN directly influences the water solubility (WS) of a protein and, thus, the functional properties in general. Regarding the UA, the ideal for a protein flour is 0.05 to 0.2. An activity higher than 0.2 indicates a poor heat treatment, and lower than 0.05 indicates an over-processing and possible damage to the protein quality [35]. The SI and SMI had a UA of 0.04 and 2.32, respectively, indicating that the SI was over-processed, while the heat treatment applied to SMI was insufficient to inactivate urease. As for hydrolysates, the UA was around 0.085; therefore, the processing was adequate. [PERSON] et al. [36] reported for soybean proteins a UA of 0.109, and 0.252 for a commercial and a Brazilian variety named Bays. The functional properties provide information on the physicochemical behavior of the protein in a food system. The SMI was 10% more hydrosoluble than the commercial soybean counterpart. Interestingly, the SMH was 52% more soluble than soybean because it had a higher degree of hydrolysis or FAN value. The SH has less FAN than the isolate, despite being a hydrolyzed sample, resulting in a protein with lower solubility. Another factor that could have influenced the observed higher solubility of soybean-maize proteins is protein composition as they contain higher amounts of albumins from the germ of maize. The protein fractionation studies show that legumes with higher albumin content have better solubility than counterparts with a high concentration in globulins [25]. The NSI of SMI and SMH proteins was 25% and 41% higher than soybean, respectively. The NSI determined for the analyzed proteins coincides with that reported for vegetable proteins. [PERSON] [33] reported that the NSI values of soybean flours concentrate and isolates ranged between 10% and 90%. [PERSON] et al. [37] reported an NSI of 21.2% for soybean isolate. NSI values of 23.1%, 46.3%, and 50.3%, respectively, were reported for other legumes such as peas, chickpeas, and lentils [38; 39; 40].