In this paper, there were compared some functional properties of the protein preparations obtained from bean seeds using two methods: a classical isolation and crystallization under the acidic conditions. The compared functional properties were: the protein solubility as a function of pH, the surface aromatic hydrophobicity at pH 2.8 and 8.0, and the emulsifying activity index (EAI)]. During the classical isolation process, the proteins were recovered from an alkaline extract at a minimum solubility pH, and their form was amorphous (PBA). While using the second method, the ability of bean proteins to create crystalline structures under the acidic conditions (PBK) was utilized. The crystalline proteins obtained had a lower surface aromatic hydrophobicity at both pH values: 2.8 and 8.0, a lower water absorbability and EAI comparing to PBA. The high hydrophobicity of the crystalline and amorphous proteins under the acidic conditions implies that they might have better functional properties in this environment. It was stated that while heating the preparations at 100°C for 30 minutes, their hydrophobicity, water absorbability, and EAI values rose higher in PBK than in PBA. Crystalline proteins preparations had worse functional properties if compared to the amorphous ones, and this fact results from their different composition and structure.