## 6 Directions of Use of Potato Protein Preparations  
Proteins with high nutritional value and with favorable functional properties can be an attractive food additive. Similarly to functional properties, the optimal amino acid composition and digestibility making up the nutritional value of the proteins obtained are closely related to their conformation, which in turn results from the conditions of protein isolation from the raw material. Therefore, depending on the method of isolation and the applied factors, such as pH, ionic strength and temperature [4; 5; 9; 51], the directions of using potato protein preparations will be different. The need to monitor and remove phytochemicals occurring in them in varying amounts is also associated with obtaining proteins from plant raw materials for food purposes. These are naturally occurring polyphenols in raw materials and toxic substances, such as glycoalkaloids \(\alpha\)-solanine and \(\alpha\)-chaconine [78]. Produced in the starch industry, relatively cheap fodder potato protein, containing approximately 80% of raw protein in dry matter and several percent of carbohydrates and 3-5% of ash ingredients, does not show functional properties and has an intense flavor and aroma as well as a gray color [79]. Thus, it does not exhibit biological activity and its use is limited only to feed purposes. Preparations containing potato proteins with an unchanged structure are proposed for use in food production as nutritional, health-promoting and functional ingredients but also as components with a technological effect, e.g., in filtration processes, or as substances showing a beneficial non-food effect. An important argument for their use in food production in place of the used protein preparations of other origin is the much less common allergenity [9] of potato proteins. In food production, preparations of both natural plant-based and modified proteins are used, with the most commonly used proteins being hydrolysates. [PERSON] and [PERSON] [80], leading the limited enzymatic hydrolysis of heat-coagulated potato proteins, showed an increase in its solubility by 14-19 fold. Hydrolyzed potato proteins used by these authors to produce frankfurters at a dose of 2.5% contributed to the extension of the quality of these products under refrigeration conditions. The products that they obtained showed significantly lower cooking losses, fracture force and lipid oxidation than the products without the addition of potato proteins [9]. Patatin, due to its chemical properties similar to animal proteins, including an apparent molecular weight of around 40 kDa and an isoelectric point at pH 4.6, is widely used as a clarifying agent in oenology [81]. For example, patatin proteins (supplied by Solanic) have been used as a grape must clarifier in place of traditionally used clarifiers such as potassium caseinate and the synthetic PVPP polyvinylpolypyrrolidone polymer. By using clarifying agents, browning and cloudy musts are prevented. The activity of patatin proteins in reactions with phenolic compounds, plant dyes and pectin compounds causing inappropriate must color and turbidity was comparable to or better than that of potassium caseinate. Patatin proteins also turned out to be an important clarifying agent in the treatment of red wines, reducing their astringency [82], and, in other studies, a clarifying agent replacing egg albumin and casein [83]. The promising flocking properties of patatin require further research to determine the effects of pH and temperature on these properties, as well as the ability to retain must components that affect wine aroma [82]. Partially thermally denatured potato protein preparations were used as nutritional and texturizing additives for mashed potatoes [84], potato snacks [85; 86] and corn snacks [87]. As shown by these studies, the addition of potato protein concentrates had a positive effect on the texture of crisps, both fried and extruded.