## 5 Effect of the Potato Protein Isolation Method on the Properties of the Obtained Preparations
According to the studies conducted by these authors, most protease inhibitors are adsorbed by the clay minerals at pH 7 to 9, while patains can be absorbed at pH 4-6. This was an approach for the separation of patatin and protease inhibitors proteins using clay minerals as cation exchangers. An interesting solution of the technology of obtaining native potato proteins is the expanded bed adsorption chromatography modifications, in which membrane adsorber capsules (MA-IEX) are replaced with modules for direct purification of native proteins, skipping the first stages of purification (pre-filtration/microfiltration). The developed process consisted of only three-unit operations and enabled the direct and continuous isolation and purification of native potato proteins from raw potato fruit juice (PFJ) in the form of white powdered products suitable for human nutrition due to the lower content of antimutrients [74]. Other authors [1] paid attention to the possibility of obtaining a group of thermally stable proteins of the protease inhibitors with potential antimicrobial activity, dissolved in deproteinized fruit water, remaining after thermal protein coagulation in potato fruit juice (PFJ). These authors found a significant impact of the height of the isolation temperature of proteins from industrial potato fruit juice (PFJ) on the composition, structural stability,as well as on trypsin inhibitors and the antifungal activities of proteins remaining in the waste effluents. In the 80 \({}^{\circ}\)C coagulation effluent, they identified the predominant presence of low-molecular inhibitory protein fractions (5-17 kDa), which, compared to the waste effluents after treatment at other temperatures (40 and 60 \({}^{\circ}\)C), were characterized by higher antifungal activity against five strains of Fusarium species. They included them in the group of protease inhibitors I with a molecular weight of around 12 kDa and II 16 kDa proteins. On the other hand, in the effluent after coagulation at lower temperatures (40 and 60 \({}^{\circ}\)C), they identified the presence of various fractions of inhibitor proteins, which they classified as aspartic, cysteine and serine protease inhibitors, including Kunitz-type protease inhibitor proteins with a molecular weight ranging from 20 to 24.5 kDa. The studies conducted by these authors showed that Kunitz-type serine protease inhibitors are thermally stable and fully functional up to the temperature of 80 \({}^{\circ}\)C and showed high activity against different strains of Fusarium. Additional studies by other authors [31; 50] confirmed the activity of these inhibitor protein fractions. The groups of Kunitz-type serine protease inhibitors, AFP-J, PT-1 and Potide-G proteins, isolated by some authors [58; 75; 76], showed marked antimicrobial activity. Scientists are becoming increasingly interested in methods for releasing proteins from material rich in non-starch polysaccharides. They use sets of enzymes that break down these compounds, both in the potato juice and in the pulp. This additionally enables the degradation of starch with amylases, such as the \(\alpha\)-amylase from Bacillus licheniformis. According to [PERSON] et al. [77], it is possible to effectively obtain proteins from potato pulp produced in the starch industry, using appropriately selected sets of enzymes with a multi-enzyme action on non-protein components. After using the Termamyl amylase, these authors further degraded plant cell wall components with polysaccharide-hydrolyzing enzymes, and then extracted proteins. In another study [2], they showed that, for industrial purposes, it is beneficial to use multi-enzymatic preparations with a broader spectrum of glycosyl-hydrolase interaction, due to the greater efficiency of isolation of highly functional proteins from potato pulp. To prevent hydrolysis of the potato proteins, it was important to select an enzyme system that led to no or a negligible degree of protein hydrolysis (low or no proteolytic activity on potato proteins).