# Effect of Extraction Method and Thermosonication on Apple Juice Quality
## 3 Results and Discussion
### Influence of Ultrasound Treatment on Microorganism Content in Apple Juice  
Juice preservation with the use of pasteurization (P) resulted in complete destruction of mesophilic microorganisms. During storage of pasteurized juice independent of storage temperature, the total microbial count was 0 cfu/mL (Tables 3 and 4). After treatment U1, i.e., at an intensity of 17.5 W cm\({}^{-2}\), in freshly extracted juice the microorganisms were deactivated. During storage of juice at 4 \({}^{\circ}\)C for 72 hours (3 days) their growth was not observed. After 120 hours (5 days) the total microorganism count was nonquantifiable for juice stored at 4 \({}^{\circ}\)C and 20 \({}^{\circ}\)C. Applying treatment U2 at an intensity of 25 W cm\({}^{-2}\) turned out to be efficient in terms of prolonging the shelf life of juice stored at 4 \({}^{\circ}\)C. Over 144 hours (7 days), the amount of microorganisms remained at a low acceptable level, and only after 216 hours (9 days) the quality of juice deteriorated drastically and the total microorganism count was nonquantifiable. The efficacy of ultrasound on microorganisms depends on the physicochemical properties of food, the volume of food being processed, the types of microorganisms, the treatment temperature, the power level, and the duration of ultrasound treatment [25; 42; 43]. The efficacy of treatment U2 (25 W cm\({}^{-2}\)) in the destruction of microorganisms in juice is associated with a synergistic effect. On the one hand, the microorganism destruction is associated with the phenomenon of cavitation and the effect of air bubbles on their cell walls (source); on the other hand, the juice temperature increased to 48.5 \({}^{\circ}\)C during sonication, above the lethal level [17]. This was confirmed by the study of [PERSON] and [PERSON] [44], who demonstrated that using only ultrasound to destroy microorganisms is insufficient and combined methods should be used for this purpose.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Device Type**} & \multicolumn{6}{c}{**Storage Time (h)**} \\ \cline{2-7}  & **Control** & **24** & **48** & **72** & **96** & **120** \\ \hline Decanter & 400 \(\pm\) 20a & 450 \(\pm\) 22a & 470 \(\pm\) 25a & 480 \(\pm\) 31a & 500 \(\pm\) 32a & nqf \\ \hline Twin-screw press & 80 \(\pm\) 7b & 240 \(\pm\) 11b & 300 \(\pm\) 27b & 320 \(\pm\) 28b & 350 \(\pm\) 27b & nqf \\ \hline Piston press & 40 \(\pm\) 6c & 80 \(\pm\) 7c & 100 \(\pm\) 7c & 120 \(\pm\) 8c & 150 \(\pm\) 8c & nqf \\ \hline \hline \end{tabular}
\end{table}
Table 1: Total number of mesophilic microorganisms (colony forming units (cfu)/mL) in apple juice obtained with various devices stored at 4 \({}^{\circ}\)C. Different letters in the same column indicate values significantly different at P \(<\) 0.05.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Device Type**} & \multicolumn{6}{c}{**Storage Time (h)**} \\ \cline{2-7}  & **Control** & **24** & **48** & **72** & **96** & **120** \\ \hline Decanter & 400 \(\pm\) 20a & 500 \(\pm\) 22a & nqf & nqf & nqf & nqf \\ \hline Twin-screw press & 80 \(\pm\) 7b & 300 \(\pm\) 15b & 500 \(\pm\) 27a & nqf & nqf & nqf \\ \hline Piston press & 40 \(\pm\) 6c & 70 \(\pm\) 7c & 400 \(\pm\) 25b & nqf & nqf & nqf \\ \hline \hline \end{tabular}
\end{table}
Table 2: Total number of mesophilic microorganisms (cfu/mL) in apple juice obtained with various devices stored at 20 \({}^{\circ}\)C. Different letters in the same column indicate values significantly different at P \(<\) 0.05.