## 3 Results and Discussions
### Ascorbic Acid Content  
An initial content of 42.7 \(\pm\) 0.2 mg ascorbic acid/100 g of pulp was found, similar to those reported by [PERSON] et al. [44] and [PERSON] et al. [30] in organic crops in Brazil (Table 4).  
A significant decrease (\(p\) < 0.05) in the content of ascorbic acid was observed in the treatments at 30 kHz for 10 and 20 min on day zero (Table 4). A small production of reactive species due to the lower degassing rate than the other treatments allows reactive species formation. In this way, aerobic oxidation could explain the ascorbic acid losses reflected in these two treatments, which agrees with the trend found in several juices and fresh fruit pulps processed by ultrasound [51], as the juice of _Physalis perwiviana_ L. (Uchuva) [39] in _Passiflora edulis_ f. _flazicarpa_ (yellow passion fruit) [52]. Ascorbic acid's oxidation can be caused by the addition of oxygen during the opening of the fruit and handling when working the pulp and by the formation of free radicals during the application of ultrasound, which can form reactive species such as H, OH, HO2, O, and H2O2, and therefore cause its oxidation immediately [51].  
On the contrary, there was a significant increase in ascorbic acid content in the treatments, reaching values of up to 49.1 \(\pm\) 3.1 mg ascorbic acid/100 g of pulp on day 8 of storage. The increase might be caused by the fruit's opening that begins to slowly release some organic acids present at the membranous sacs' level as a protection mechanism,  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Power (kHz)**} & \multirow{2}{*}{**Time (min)**} & \multicolumn{6}{c}{**Days after Treatment**} \\ \cline{3-8}  & & **0** & **4** & **8** & **12** & **16** & **20** \\ \hline Control & & 42.7 \(\pm\) 0.2 cB & 42.4 \(\pm\) 0.1 cA & 40.9 \(\pm\) 2.6 bA & 40.7 \(\pm\) 0.1 bB & 42.9 \(\pm\) 8.5 cD & 21.6 \(\pm\) 2.9 aA \\  & 10 & 39.4 \(\pm\) 1.1 bA & 49.7 \(\pm\) 4.9 dC & 48.5 \(\pm\) 1.5 dC & 43.8 \(\pm\) 4.4 cB & 42.0 \(\pm\) 0.2 cD & 22.1 \(\pm\) 3.0 aA \\
30 & 20 & 40.1 \(\pm\) 2.3 cA & 45.7 \(\pm\) 3.7 dB & 45.8 \(\pm\) 3.8 dB & 36.7 \(\pm\) 3.0 bA & 34.5 \(\pm\) 2.3 bA & 20.9 \(\pm\) 2.7 aA \\  & 30 & 42.9 \(\pm\) 0.7 cB & 46.6 \(\pm\) 4.7 dB & 48.7 \(\pm\) 2.0 dC & 41.0 \(\pm\) 2.1 bB & 38.7 \(\pm\) 2.4 bC & 23.0 \(\pm\) 2.6 aB \\  & 10 & 41.7 \(\pm\) 1.2 cB & 43.4 \(\pm\) 3.4 dA & 44.2 \(\pm\) 2.8 dB & 33.9 \(\pm\) 3.2 bA & 31.8 \(\pm\) 2.4 bA & 24.5 \(\pm\) 2.1 aB \\
40 & 20 & 42.0 \(\pm\) 1.7 cB & 46.9 \(\pm\) 5.8 dB & 49.1 \(\pm\) 3.1 dC & 40.3 \(\pm\) 1.5 bB & 38.3 \(\pm\) 3.8 bC & 24.1 \(\pm\) 2.8 aB \\  & 30 & 43.1 \(\pm\) 1.7 cC & 46.3 \(\pm\) 3.42 dB & 48.3 \(\pm\) 4.1 dC & 40.0 \(\pm\) 4.7 bB & 36.6 \(\pm\) 1.6 bB & 23.8 \(\pm\) 3.5 aB \\ \hline \hline \end{tabular} Data expressed as mean \(\pm\) standard deviation of three repetitions. In the same row, different lowercase letters indicate statistically significant differences between treatment days (\(p\) < 0.05). In the same column, different capital letters indicate statistically significant differences between the treatments (\(p\) < 0.05).  
\end{table}
Table 4: Ascorbic acid content (mg/100 g of pulp) during storage at 4 °C of the pulp of _Passiflora edulis_ f. _dulis_ Sims (_gulupa_) subjected to low-frequency ultrasound treatments.  
including ascorbic acid. From day 12, the content began to decrease, presenting the lowest values on day 20 of storage. In general, the 30 kHz treatments for 30 min and all the 40 kHz treatments showed the highest ascorbic acid values at the end of the storage period, which suggests that degassing is essential to prevent the oxidation of the pulp components.