## 3 Results and Discussion  
### mPAGE Analysis of Soy Protein Hydrolysates  
In agreement with our previous study, [PERSON] et al. [10], bromelin, Neutrase and trypsin ensured different hydrolysis degrees (HDs) of soy protein isolate. Among all the tested enzymes, bromelin was the most efficient in hydrolyzing the soy proteins (HD of 10.3%), being followed by Neutrase (HD of 9.7%) and trypsin (HD of 1.9%). The electrophoretic analysis was employed to check the molecular weight distribution of the resulting peptides, separated through centrifugation into soluble and insoluble fractions. The mPAGE analysis revealed that the SPI used in the study has high amounts of 75 (\(\beta\)-conglycinin) and 11S (glycinin), which are the major globulins found in soybeans [18]. Figure 1 (lane SPI) emphasizes the specific subunits of the main globulins found in soybeans: \(\alpha^{*}\) (-75 kDa), \(\alpha\) (-72 kDa) and \(\beta\) (-53 kDa) subunits of \(\beta\)-conglycinin, together with the acidic (33-42 kDa) and basic subunits (-22 kDa) of glycinin [19; 20].  
Analyzing the results presented in Figure 1, one can observe that the soluble fraction of soy protein hydrolysates retained only the peptides with molecular weights lower than 20 kDa (lanes sSPB, sSPN, sSPT). On the other hand, the insoluble fractions (residuals)of soy protein hydrolysates retained higher molecular weight fragments (Figure 1, lanes rSPB, rSPN, rSPT), probably resulting from the partial digestion of the main soy proteins (lane SPI in Figure 1). The smearing in the rSPB, rSPN and rSPT lanes (Figure 1) might also suggest the rather low specificity of exogenous proteases used in this study. In agreement with our observations, [PERSON] et al. [21] reported the reducing of the number of protein bands as a consequence of the Alcalase-assisted hydrolysis of the \(\alpha^{\prime}\) and \(\alpha\) subunits of \(\beta\)-conglycinin, together with the decrease in the antigenic properties. Moreover, [PERSON] et al. [22] emphasized that soy protein hydrolysis with Alcalase and Neutrase resulted in 84 peptides with immunoregulatory activities and other positive effects on human health. In addition to modulating the functional properties of the soy protein isolate, enzyme-assisted hydrolysis might also allow for the reduction in allergenic properties. Various studies assigned the allergenic properties of soybeans to various 7S and 11S globulins [23; 24] or to proteins located in soybean hulls [25; 26]. The major soybean protein allergens are considered to be Gly m 4 (17 kDa), Gly m 5 (\(\beta\)-conglycinin) and Gly m 6 (with five subunits having polypeptides of 20 kDa and 40 kDa) [26; 27]. Some other proteins responsible for allergenic activities were described as Gly m1, Gly m 2, Gly m 3 or 2S-globulin fraction, having lower molecular weights of 7 kDa, 7.5 kDa, 8 kDa and 12-15 kDa, respectively [19; 20]. To reduce or eliminate the allergenicity of foods based on soybean proteins, different thermal and non-thermal treatments were applied. Among these treatments, enzyme-assisted hydrolysis appears very efficient for altering the structure of allergenic proteins. This effect of allergenic potential reduction associated with hydrolysis with exogenous enzymes is of particular interest in the case of those proteins which are resistant to in vivo digestion, as is the case of soy proteins [10]. The results presented in Figure 1 suggest that the separation of the soluble fraction of the soy protein hydrolysates obtained with bromelain or Neutrase might allow for obtaining soy protein ingredients devoid of such allergens.