## 3 Results
### Content of Phenolic Compounds
#### 3.3.1 Content of Non-Anthocyanin Phenols
An approximately 20% lower content of phenolic compounds in the juice obtained from the mash after ultrasonic treatment at 50 \({}^{\circ}\)C compared to the enzymatic treatment for acerola mash (Pectinex Ultra SP-L preparation) was also noted by [PERSON] et al. [12]. [PERSON] et al. [25] indicate that the effectiveness of ultrasound largely depends on parameters, such as temperature, frequency and power. In the conducted studies, a beneficial effect of the use of temperature (50 \({}^{\circ}\)C) on the content of phenolic compounds was noted. Some researchers indicate that the most optimal extraction of phenolic compounds is with ultrasound at temperatures up to 60 \({}^{\circ}\)C [48]. They suggest that phenolic compounds can be hydrolyzed and oxidized at higher temperatures when they are extracted for a longer time [26]. The profile of phenolic compounds present in the raw material also seems to be an important issue. For instance, [PERSON] and [PERSON] [18] found that the most optimal temperature for the ultrasonic treatment of grapes is 74 \({}^{\circ}\)C. These findings may indicate an important role of the phenolic profile but also of the tissue structure of the raw material in the optimization of process parameters. The aforementioned authors noted a more favorable effect of ultrasonic mash treatment compared to enzymatic treatment. Thus, it seems that further research on the use of thermosonication for fruit mash processing in a wider range of temperatures should be conducted. In the case of the use of ultrasounds alone for mash treatment, as in the case of ascorbic acid, degradation of phenolic compounds by sonolysis or oxidation may play a significant role. Especially as non-anthocyanin phenols are often directly oxidized in enzymatic reactions. In this case, an increase in the content of the tested compound in the juice may also be associated with more effective deaeration of the mash. Procyanidins, catechin, quercetin, kaempfer, ellagic acid derivatives and p-coumaric acid were identified in the profile of non-anthocyanin phenols. Procyanidins accounted for 55-63% of the content of these compounds. The dominant share of these compounds was also noted by [PERSON] et al. [2] who examined different strawberry genotypes. In the tested samples, the highest yield of procyanidins was found for juices from mash after thermal treatment followed by enzymatic treatment. [PERSON] et al. [49] found an approximately 15% increase in procyanidins in strawberry pure under the influence of heat treatment used in the technological process. In turn, the effect of enzymatic treatment on the improvement of extractability of procyanidins into juice is described by [PERSON] et al. [50] for blackcurrant and by [PERSON] et al. [10] for lingonberry. In the case of p-coumaric acid, pectinolysis was the most effective. For catechins, the highest content in the juice was obtained after pectinolysis and vacuum-assisted pectinolysis. The latter method was also most effective for quercetin and ellagic acid derivatives. The highest content of kaempfer was as a result of thermosonication. The content of individual phenolic compounds in the juice can be determined both by improving the extractability of the tested compounds from the tissue and by the degrading effect. The literature data show that compounds, such as procyanidins, catechins, quercetin and ellagic acid derivatives,occurring largely in achene are strongly associated with the tissue matrix. Hence, the higher efficiency of their extraction as a result of the use of mash pectinolysis may result [51]. Only in the case of kaempfer, which is mainly located in the epidermis, a higher efficiency of sonication was noted [52]. In addition, some of these compounds, especially catechins, are good substrates in the process of enzymatic oxidation, which may cause their degradation during ultrasonic treatment of the mash.