## Results
### Volatile Organic Compounds

Table 2: _Cont._The PCA provides two principal components (PC), which together represent 98.2% of the total variance in VOCs profiles. The effects of cutting, sHWT temperature and duration of storage can be visualized by a scatter point plot (Figure 2A). Decreasing values of PC1 (representing 65.3% of total variance in VOCs profiles) can be associated with the effects of cutting, while increasing values are associated with storage time. Decreasing values of PC2 (representing 33.0% of total variance in VOCs profiles) can also be associated with cutting, and, beyond that, with the distinct effects of the various treatments. Interestingly, sHWT at 55 \({}^{\circ}\)C induced the highest alteration of the VOCs profile from that of intact apples (c.f. colored bars in Figure 2A). For both PCs, the impact of each single VOC on the total variance in the VOCs profiles can be identified as visualized in Figure 2B. Mostly, ethyl acetate (es1) and, to a much smaller extent, ethyl 2-methylbutanoate (es15) and ethanol (al1) are related to effects of the sHWT (PC2), but also to changes during storage (PC1). Cutting-induced changes in the VOCs profiles (both PC decreased) are mainly associated with 2-methylbutyl acetate (es5), but also with isobutyl acetate (es4), butyl acetate (es3) and hexyl acetate (es7). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Treatment** & **Reaction** & **VOCs** &
\begin{tabular}{c} **Aroma Threshold** \\ **Values (nL L\({}^{-1}\))** \\ \end{tabular} \\ \hline all sHWT & \(\uparrow\) & Ethanol & 8–900 \({}^{\text{a}}\)/\(>\)1 \(\times\) 10\({}^{5,\text{b}}\) \\  & \(\downarrow\) & Propyl acetate & 2000–11,000 \({}^{\text{a,b}}\) \\  & & Estragole & n/a \\ sHWT without cp & \(\uparrow\) & Ethanol & 8–900 \({}^{\text{a}}\)/\(>\)1 \(\times\) 10\({}^{5,\text{b}}\) \\ sHWT combined with cp & \(\uparrow\) & D-limonene & 4–229 \({}^{\text{a}}\) \\ only 55 \({}^{\circ}\)C sHWT & \(\uparrow\) & Ethyl 2-butenoate & n/a \\  & & 2-methyl-1-propanol & 360–3300 \({}^{\text{a}}\) \\  & & Ethyl acetate & 5–13,500 \({}^{\text{b}}\) \\  & & Ethyl 2-methylpropanoate & 0.01–1 \({}^{\text{a}}\) \\  & & Ethyl butyrate \({}^{\text{*}}\) & 0.1–18 \({}^{\text{a}}\) \\ only 55 \({}^{\circ}\)C sHWT & \(\uparrow\) & Ethyl 2-methylbutanoate \({}^{\text{*}}\) & 0.006–0.1 \({}^{\text{a,b}}\) \\ without cp & & Ethyl valerate & 1.5–5 \({}^{\text{a,b}}\) \\  & & Methyl hexanoate & 10–87 \({}^{\text{a}}\) \\  & & 2-butanone & n/a \\  & & Estragole & n/a \\  & & 1-penten-3-one & 400 \({}^{\text{a}}\) \\ only 55 \({}^{\circ}\)C sHWT & \(\downarrow\) & Ethyl acetate & 5–13,500 \({}^{\text{a,b}}\) \\ only 65 \({}^{\circ}\)C sHWT & \(\downarrow\) & Propyl acetate & 2000–11,000 \({}^{\text{a,b}}\) \\ \hline only sHWT at 65 \({}^{\circ}\)C or & & Ethyl propionate & 9–45 \({}^{\text{a}}\) \\ combined with cp & \(\downarrow\) & Ethyl hexanoate & 0.3–5 \({}^{\text{a}}\) \\  & & Methyl hexanoate & 10–87 \({}^{\text{a}}\) \\ \hline sHWT: short-term hot water treatment; cp: chemical prevention by applying organic acid dipping of fresh-cut slices; 55 \({}^{\circ}\)C/65 \({}^{\circ}\)C: sHWT at the specified temperature; green \(\uparrow\): increase; red \(\downarrow\): decrease. Given are aroma threshold values according to \({}^{\text{a}}\) [PERSON] [30] and \({}^{\text{b}}\) Dixon and Hewett [29]. \({}^{\text{*}}\) marked VOCs described as generally important “character impact” compounds in apples [29]. & 10–87 \({}^{\text{a}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Treatment-specific qualitative changes in the emissions of relevant VOCs and corresponding aroma threshold values of fresh-cut apple slices stored in sugar syrup at 4 \({}^{\circ}\)C for up to 13 days.