Most potato proteins are fractions of albumin and globulin, soluble in water and in water and salt solutions, respectively; these are patatin glycoproteins, with a pIs in the range of 4.8–5.2. This group of proteins is typical of potato and they are referred to as patatin or tuberin. Around 30–50% of soluble potato proteins comprise numerous fractions of protease inhibitors with a molecular weight in the range of 7–21 kDa; they are often heat-resistant, showing a wide spectrum of health-promoting effects. The nutritional value of proteins is related to the content of amino acids, their mutual proportions and digestibility. Natural proteins of the patatin fraction are characterized by favorable functional properties, including foam formation and stabilization, fat emulsification or gelling. Native potato proteins may also exhibit beneficial non-food properties, such as antimicrobial or antitumor, as well as antioxidant and antiradical. Depending on the method of isolation and the applied factors, such as pH, ionic strength and temperature, the directions of using potato protein preparations will be different.

Potatoes of six cultivars (Solanum tuberosum L.) with red, purple, and yellow flesh were stored at 2 and 5 °C for 3 and 6 months, and the influence of these factors on the content of free amino acids was determined. The potato cultivar and storage time had the greatest impact on the free amino acid content. The tubers of red-fleshed (Rote Emma) and purple-fleshed (Blue Congo) potatoes contained over 28 mg/g DM of free amino acids, and the Blaue Annelise cultivar with purple flesh had over 18 mg/g DM. After 6 months, the highest increase in their content (by 36%) was recorded in tubers of the Fresco cultivar (yellow-fleshed). In the analysed potatoes, the content of alanine, proline, serine, γ-aminobutyric acid, and α-aminoadipic acid increased, while that of asparagine, aspartic acid, and glutamine decreased. Asparagine decreased to the greatest extent in “Blaue Annelise” potatoes (by 24%) and that of glutamine in tubers of Rote Emma and Vineta by 18%.

Potato sprouts could be a valuable resource of phytochemicals such as secondary plant metabolites, potential antioxidants and nutritive compounds. In this work, potato sprout extracts of five varieties were examined; they differed in major glycoalkaloid content, trypsin inhibitor activity, total polyphenol content and antioxidant activity, as well as in antimicrobial activity against Gram + and G − bacteria, and yeast. Sprouts of colored-fleshed tubers were characterized by higher trypsin inhibitor activity than sprouts of yellow potatoes. The strongest microorganism growth inhibition effect was observed for macerate with sprouts from the purple-fleshed Blaue Annelise variety against B. subtilis, whereas C. albicans yeasts were sensitive to macerates with sprouts from purple-fleshed Blue Congo and yellow-fleshed Vineta potato varieties.

Glycoalkaloids (TGAs, total glycoalkaloids), toxic secondary metabolites, are found in potatoes (110–335 mg·kg⁻¹ DW), mainly in the peel. Colorful, unpeeled potatoes are an innovative raw material for the production of snacks which are poorly tested in terms of their glycoalkaloid content. Third-generation snacks and French fries made from red-fleshed Mulberry Beauty (MB) and purple-fleshed Double Fun (DF) potatoes were produced with the use of 1% solutions of ascorbic, citric, lactic, malic, and tartaric acids to stabilize the structure of anthocyanins in the raw material and maintain their color in obtained products. The influence of the type of acid and thermal processes, like frying, microwaving, and baking, on the content of glycoalkaloids in ready-made products was examined. Only 0.45–1.26 mg·100 g⁻¹ of TGA was found in pellet snacks and 1.32–1.71 mg·100 g⁻¹ in French fries. Soaking blanched potatoes in organic acid solution reduced the α-chaconine content by 91–97% in snacks and by 57–93% in French fries in relation to the raw material to the greatest extent after the use of malic acid and the DF variety. The effect of lactic and citric acid was also beneficial, especially in the production of baked French fries from MB potatoes.

The aim of the experiment was to study the influence of thermal coagulation of protein in potato juice isolated from tubers of three potato varieties cultivated conventionally and in ecological system on amino acid composition and nutritive value of obtained preparations. A soil fertilizer and copper salt 50 WP as a fungicide were used within ecological system of potato cultivation and in conventional system fertilizing with high doses of NPK, herbicides, insecticides and fungicides were applied. Protein coagulation was performed in juice containing dissolved CaCl2. After suitable hydrolysis of the obtained concentrates, the chemical composition and contents of 18 amino acids were determined in total protein with the use of automatic amino acid analyser. Potato protein concentrates (PPC) obtained from tubers cultivated within ecological system contained more nitrogen compounds and also forms of protein nitrogen than there were found in preparations originating from juice of tubers cultivated conventionally. Also, in amino acid composition of isolated protein we found more such essential amino acids as Leucine, Phenylalanine, Tyrosine and Threonine. Among remaining amino acids in PPC originating from potatoes cultivated within ecological system there was more of Asparagine acid, Serine and Glycine. Chemical Score (CS) expressing nutritive value of studied concentrates, in dependence of protein standard chosen for comparison occurred similar or higher than it was established for standard, particularly in the case of preparations obtained from tubers cultivated within ecological system. Celem przeprowadzonych badań było określenie wpływu termicznej koagulacji białek w soku ziemniaczanym uzyskanym z bulw trzech odmian ziemniaka uprawianych systemem konwencjonalnym i ekologicznym na skład aminokwasowy i wartość odżywczą uzyskanych koncentratów białkowych. W uprawie ziemniaka systemem ekologicznym stosowano użyźniacz glebowy i fungicyd, miedzian 50 WP, a w uprawie systemem konwencjonalnym nawożenie wysokimi dawkami NPK, herbicydy, insektycydy i fungicydy. Koagulację białka w soku przeprowadzono z udziałem CaCl2. Oznaczono skład chemiczny otrzymanych preparatów oraz zawartość 18 aminokwasów w białku ogółem, po uprzedniej hydrolizie białka, przy użyciu automatycznego analizatora aminokwasów. Koncentraty białkowe otrzymane z bulw uprawianych systemem ekologicznym zawierały więcej związków azotowych, w tym form azotu białkowego niż preparaty uzyskane z soku bulw pochodzących z uprawy konwencjonalnej. Również w składzie aminokwasowym wyodrębnionych białek stwierdzono więcej takich aminokwasów egzogennych, jak: leucyna, fenyloalanina i tyrozyna oraz treonina, a wśród pozostałych aminokwasów więcej kwasu asparaginowego, seryny i glicyny. Wskaźnik wartości odżywczej CS badanych koncentratów, w zależności od przyjętego białka wzorcowego był zbliżony lub przewyższał wartości przewidziane dla standardu, szczególnie gdy preparaty pochodziły z surowca uprawianego systemem ekologicznym.

Potatoes with colored flesh are increasingly processed in the food industry. However, establishing appropriate production parameters is challenging because anthocyanins and other polyphenols present in potatoes undergo structural transformations during processing. Therefore, this study investigated the effects of five organic acids applied during the production of dehydrated potato grits on the content, profile, and stability of phenolic compounds in the final products manufactured from tubers of the red-fleshed potato cultivar Lily Rose (LR) and the purple-fleshed cultivar Double Fun (DF). The effects were assessed by analyzing the profiles, antioxidant activity, and content of the phenolic compounds in the final products. Phenolic compounds were analyzed by high-performance liquid chromatography (HPLC), while antioxidant activity was evaluated using the FRAP, DPPH, and ABTS assays. Only malic acid improved anthocyanin retention in LR potato products, while tartaric and malic acids had the greatest effect on the content of the analyzed compounds in DF potato products. Citric acid showed only a moderate stabilizing effect on anthocyanin content. Grits produced with malic and tartaric acids contained 20–67% more phenolic acids than the control and showed higher antioxidant activity. Lactic acid had an adverse effect, particularly in LR dehydrated potato grits. Depending on the potato cultivar, the effectiveness of organic acids in stabilizing anthocyanins varied. Therefore, the processing conditions for colored potatoes should be optimized for the specific cultivar.