## 3 Results and Discussion
### Changes in Raw Material Caused by Pre-Treatment in Ethanol Solution with and without Ultrasound
The highest conductivity value (82.52 \(\pm\) 2.30 \(\upmu\)S/cm) was obtained after the longest treatment time (180 s) for EtOH+US40. Thus, the increase in the conductivity value was over 19.3% with respect to the conductivity value for the alcohol solution after the same treatment time without US assistance (EtOH--66.60 \(\pm\) 1.99 \(\upmu\)S/cm). Colour is one of the most important parameters for assessing the quality of raw materials and food products. From the perspective of a potential consumer, colour is one of the basic factors that influence the acceptability of a product [31,33]. Therefore, it is very important to control colour changes after pre-treatments. This allows to check whether the application of the treatment or process is useful for industrial purposes and allows to maintain the colour of the raw material. Table 2 shows the changes in colour parameters of carrot slices after pre-treatment in ethyl alcohol with or without ultrasound support. For the fresh carrot, the L*, a * and b* parameters were equal to 40.6 \(\pm\) 2.1, 12.3 \(\pm\) 3.0, and 23.4 \(\pm\) 3.8, respectively. The fresh material has an orange colour with the hue angle (h\({}^{\circ}\)) equal to 62.6 \(\pm\) 2.2. The treatment in the ethyl alcohol caused alteration of colour parameters. There was a lack of any trend in the L* value changes and this parameter decreased at the beginning of the treatment and after the longest time of treatment increased in comparison to fresh sample. The sonication assistance resulted in a higher L* value. In the case of a* and b* values, the treatment in alcohol resulted in most cases lowering of the value. Therefore, the total colour difference, describing the colour changes in comparison to fresh material, was characterized by value in the range of 5.4-12.3. According to [PERSON] et al. [40] the value higher than 2 indicates a visible change, which can be noted by an inexperienced observer as a consumer. It means that all treatments with ethanol resulted in significant colour modifications. Despite the changes in colour parameters, the majority of the parameters of the preliminary treatments did not significantly affect the hue angle (h\({}^{\circ}\)) of the researched carrot slices. The h\({}^{\circ}\) values were in ranges from 61.1 to 67.2 (EtOH), 62.9-68.4 (EtOH+US21) and 61.8-74.0 (EtOH+US40). Therefore, all values did not exceed 90\({}^{\circ}\), which means that both fresh carrots and those subjected to preliminary treatments were characterized by a red-orange colour. Carotenoids are an important group of pigments naturally found in plants. The best-known carotenoid is caroten, which has an orange colour. Carrots are a vegetable rich in carotenoids, in particular, \(\upalpha\)- and \(\upbeta\)-carotene, which are precursors to vitamin A [11,41]. The scientific literature reported a wide range of the carotenoid content in carrot roots, depending on the variety of the carrot, climatic aspects, soil conditions [42,43], year of growth [43], extraction methods [44], and methods of processing [45]. The total content of carotenoids in the edible part of carrot roots ranges from around 5.8 to 311 mg/100 g f.w. (fresh weight) [2,43,46]. Thus, the content of pigments in the product affects its colour and it has an impact on product acceptability. Figure 2 presents changes in the carotenoid content in raw tissue (untreated) and after 60 and 180 s of treatment in ethanol with and without sonication assistance. The samples subjected to a shorter time of immersion in ethanol (5 and 15 s) were not analysed due to the negligible effect on the total carotenoid content in carrots. The content of carotenoids in raw carrot was 53.60 \(\pm\) 4.78 mg/100 g d.m. (dry matter), which referred to the content of 5.20 \(\pm\) 0.46 mg/100 g f.w. It was thus practically in the range reported in the literature. The application of the pre-treatment, consisting of the immersion of raw carrot slices in EtOH for 60 and 180 s, resulted in an increase of the carotenoid content by 15 and 52%, respectively.