## 3 Results  
### Physicochemical Characterization  
The proximate compositions of extracted proteins are shown in Table 1. The pH for the samples was between 6.83 and 7.66. The pH affects the intermolecular forces and hydrodynamics of proteins and is commonly used to modify their structural conformation and functionality. Another parameter related to the charge of the protein is the electrical conductivity (EC). This characteristic is inherent in each protein, as it will depend on the nature and amount of charged species present. The SMI and SMH proteins had higher EC than the soybean isolate and hydrolysate, likely due to the electric charges that provide germ maize proteins.  
The isolated soybean and soybean-maize protein content was about 93%, while the hydrolysates were about 76%. This is consistent with data reported by [PERSON] et al. [24] soybean isolates and concentrates.  
The fat content for all samples was around 0.55%, except for the commercial soybean isolate, which only contained 0.09%. Ash content of samples from soybean- maize was slightly higher than that of soybean due to the maize germ's mineral content that averages 10.5% [6].  
Reducing sugars of isolates of soybean-maize and soybean proteins was 10.33 and 95.19 mg/g, respectively, while the hydrolysates of the two samples contained around 19.4 mg/g. Free alpha-amino nitrogen (FAN) of all samples was around 0.835 mg/g, except for the soybean-maize hydrolysate, which had a FAN of 2.13 mg/g.  
Heat treatment on proteins destroys anti-nutritional components such as amylase and trypsin inhibitors in legumes, thus improving the bioavailability of nutrients and the rate of protein digestibility.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Soybean Isolate (SI)**} & \multicolumn{2}{c}{**Vegetable Proteins**} & \multirow{2}{*}{**Soybean-Maize**} \\  & & **Isolate (SMI)** & & \\ \hline pH & 7.66 \(\pm\) 0.00 1 ** & 6.90 \(\pm\) 0.01 2  & 6.83 \(\pm\) 0.01 3  & 6.95 \(\pm\) 0.01 4  \\ EC (mS/cm) & 2.48 \(\pm\) 0.00 5  & 3.41 \(\pm\) 0.09 6  & 2.24 \(\pm\) 0.05  & 3.11 \(\pm\) 0.05 7  \\ Moisture (\%) & 9.25 \(\pm\) 0.03 8  & 8.87 \(\pm\) 0.12 9  & 9.30 \(\pm\) 0.34  & 4.91 \(\pm\) 0.17  \\ P (% db) & 91.82 \(\pm\) 3.36 8  & 93.91 \(\pm\) 0.11 8  & 78.38 \(\pm\) 1.99  & 73.67 \(\pm\) 1.43  \\ Fat (% db) & 0.09 \(\pm\) 0.00 9  & 0.34 \(\pm\) 0.01 3  & 0.51 \(\pm\) 0.05 3  & 0.79 \(\pm\) 0.26  \\ Ash (\% db) & 4.68 \(\pm\) 0.03 5  & 5.23 \(\pm\) 0.03 8  & 4.16 \(\pm\) 0.02 8  & 5.05 \(\pm\) 0.03 8  \\ RS (mg/g) & 95.19 \(\pm\) 0.68 8  & 10.33 \(\pm\) 0.28  & 18.30 \(\pm\) 0.62  & 20.51 \(\pm\) 0.71 8  \\ FAN (mg/g) & 0.855 \(\pm\) 0.04 9  & 0.935 \(\pm\) 0.02 9  & 0.715 \(\pm\) 0.03 8  & 2.131 \(\pm\) 0.06 8  \\ UA & 0.04 \(\pm\) 0.01 1  & 2.32 \(\pm\) 0.18  & 0.07 \(\pm\) 0.01 1  & 0.10 \(\pm\) 0.01 1  \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physical and chemical characterization of isolates and hydrolysates of soybean-maize and soybean proteins 1.  
The urease activity (UA) allows the determination of if the heat treatment used to obtain legume-based protein flours was adequate. The SI and SMI had a UA of 0.04 and 2.32, respectively. As for hydrolyses, the UA was around 0.085. The physicochemical characteristics of a vegetable protein are essential because they influence their functionality and, thus, performance in food systems.