## 3 Results and Discussion
[19], the degree of anthocyanin degradation under thermal factors is determined not only by their content in raw materials, but also by the pH process. They concluded that a pH of 3 ensures the best results in terms of anthocyanin retention and that the anthocyanin content in the finished product is largely correlated with the initial content in potatoes and mainly determined by the variety used. By contrast, [PERSON] et al. [23] stated that the amount of anthocyanins retained is linked to the blanching regime, with anthocyanin losses increasing with blanching time. These authors stated that blanching times of 2-5 min contribute to the preservation of anthocyanins in raw materials, whereas longer temperature treatments increase anthocyanin losses. Figure 2: Increasing loss of anthocyanin content (%) in potatoes after technological stages of the processing of dried potato cubes (**A**). Increasing loss of anthocyanin content (%) in potatoes after the technological stages of the processing of French fries (**B**). Increasing loss of anthocyanin content (%) in potatoes after the technological stages of the processing of chips (**C**). However, most authors [8; 10; 24] have found that these compounds are highly unstable at high temperatures. Moreover, they reported that anthocyanin losses are influenced by enzymatic oxidation processes, which occur in raw materials during cutting, crushing, or extraction. The thermal processes used in the present study are commonly used in the potato industry. Peeling was the first stage in this study, in which the potatoes were peeled manually with a vegetable peeler to a depth of over 1.5 mm, with some potato flesh removed with the peel. The process resulted in anthocyanin losses of 44%, with pelargonidin-3-caffeoryltrutinoside-5-glucoside being the most affected (69%), and with pelargonidin-3-rutinoside-5-glucose and pelargonidin-3-rutoside proving to be the most resistant (31% and 32%, respectively) (Figure 3). According to [PERSON] [25], such polyphenolic compounds as anthocyanins and phenolic acids are mainly located in the skin and the tissues directly under it, and thus, peeling may reduce their content in the tubers. [PERSON] [26] reported that the anthocyanin losses in the food industry due to peeling are approximately 7%, whereas [PERSON] et al. [27] stated that peeling potatoes to depths even as high as 2 mm does not affect the anthocyanin content. After peeling, the potatoes were diced, cut into strips or sliced (depending on the process), then rinsed with water to remove the starch released from the damaged potato cells or the excess reducing sugars. The cut potatoes were then blanched, though this step was omitted in the production process of chips, as it resulted in an inferior texture of the chips after frying (the finished product absorbed more fat and had a greasy consistency). Blanching is particularly discouraged if the potato tubers already have the optimal content of reducing sugars, while the potatoes used for making dried cubes and fries were blanched in water at 75 \({}^{\circ}\)C for 5 min. After this stage, the anthocyanin losses were found to be more significant in finely cut (diced) potatoes, reaching 68% compared to the losses of 66% found in the potato strips (Figure 2). Among the identified anthocyanins, the greatest losses were recorded for pelargonidin-3-\(p\)-coumaroyltrutinoside-5-glucoside (97%) in dried potato cube and pelargonidin-3-caffeoryltrutinoside-5-glucoside (69%) in French fries (Figure 3). The high reduction of anthocyanin content after blanching may have been caused by enzymatic oxidation processes in the raw material during cutting. The activity of o-diphenyl oxidase or peroxidase coupled with the effects of polyphenolic compounds leads to a darkened (browning) or colorless product [28; 29]. These processes irreversibly impair the organoleptic qualities of food. High-temperature processes (at over 100 \({}^{\circ}\)C) led to the most significant anthocyanin losses.