## Results and Discussion
### Volatilome of Apples after Storage  
Volatile compounds are of high importance for the odor of apples. In addition to texture, acidity and sweetness, the behavior of volatile compounds is a measure for the biochemical changes occurring in the fruit upon storage as the volatilome of the stored apples is affected by the storage conditions [53]. The general reduction of volatiles during controlled atmosphere storage--with or without MCP application--was described previously [55]. The formation of volatiles is determined by the activity of several enzyme systems that are more or less affected by the reduction of fruit respiration and ethylene biosynthesis. A previous study also reported different post-storage recovery rates of the fruits with respect to their biochemical activities showing higher aroma compound formation for RA storage than for CA or MCP conditions [56]. In this study, the volatilome of the highly ripe apples was analyzed after six months of postharvest storage under different storage conditions and compared to those of the same apples that were analyzed immediately after the harvest. A total of 52 compounds were identified as primary aroma compounds (i.e., 13 alcohols, six aldehydes, 22 esters, four ketones and seven other compounds) and 50 different compounds as secondary aroma compounds (i.e., 12 alcohols, six aldehydes, 22 esters, four ketones and six other compounds). A graphic representation of the cumulative relative concentrations of different compound classes and storage techniques is given in Figure 1. The detailed results on the semi-quantitative data of the fruit volatiles (primary and secondary flavor compounds) are given in Table 2. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Primary Aroma Compounds**} & \multicolumn{6}{c}{**Secondary Aroma Compounds**} \\ \hline \multirow{3}{*}{**Compound Name a**} & **RI** & **RI** & **Fresh d** & **CA d** & **MCP d** & **RA d** & **Fresh d** & **CA d** & **MCP d** & **RA d** \\  & **(exp.) b** & **(lit.) c** & **[ug/kg]** & [ug/kg] & [ug/kg] & [ug/kg] & [ug/kg] & [ug/L] & [ug/L] & [ug/L] & [ug/L] \\ \hline \multicolumn{6}{c}{_Alcohids_} \\ \multicolumn{6}{c}{2-Propanol} & 508 & 506 & 1.17 A & 0.33 B & 0.34 B & 0.25 B & 0.92 B & 0.98 B & 1.94 A & 1.50 AB \\ \multicolumn{6}{c}{1-Propanol} & 565 & 558 & 22.7 A & 0.19 C & 0.15 C & 6.59 C & 23.5 B & 3.48 C & 0.3 C & 44.6 A \\ \multicolumn{6}{c}{1-Propanol, 2-methyl-1-Butanol} & 632 & 635 & 28.2 A & 8.81 B & 2.12 C & 9.85 C & n.d. & n.d. & n.d. & n.d. \\ \multicolumn{6}{c}{1-Butanol} & 668 & 670 & 777 A & 75.4 C & 2.30 D & 364 D & 772.89 & 475 BC & 96.9 C & 1850 A \\ \multicolumn{6}{c}{1-Butanol, 2-methyl-1-Butanol, 767} & 740 & 738 & 876 A & 153.7 B & 82.5 C & 94.1 C & 703 B & 825 A & 456 C & 500 C \\ \multicolumn{6}{c}{1-Pentanol} & 767 & 771 & 121.8 A & 4.50 C & 0.39 D & 6.90 D & 121.9 A & 30.9 B & 3.58 C & 40.4 B \\ \multicolumn{6}{c}{2-Buten-1-ol,ol} & 774 & n.a. & n.d. D & 17.2 A & 6.46 B & 1.86 C & 10.4 C & 108 A & 55.1 B & 10.2 C \\ \multicolumn{6}{c}{2-Hexen-1-ol, (_E_)-} & 866 & 867 & 23.6 A & 2.97 B & 1.69 C & 2.76 C & 2.61 A & 27 B & 32.0 B & 32.0 B \\ \multicolumn{6}{c}{1-Hexanol} & 869 & 870 & 763 A & 55.6 C & 4.71 D & 82.1 D & 737 A & 323 C & 143 D & 537 B \\ \multicolumn{6}{c}{1-Heptanol} & 968 & 972 & 6.55 A & 0.58 C & 0.21 D & 1.63 D & 6.74 B & 3.83 C & 1.57 D & 10.6 A \\ \multicolumn{6}{c}{1-Hexanol, 2-ethyl-1-Hexanol, 1029} & 1031 & n.d. D & 0.46 C & 0.36 C & 0.52 C & 3.53 AB & 3.32 AB & 2.92 B & 3.70 A \\ \multicolumn{6}{c}{1-Octanol} & 1069 & 1070 & n.d. D & 0.39 C & 0.08 C & 1.63 C & 12.63 A & 0.79 C & 0.15 C & 6.81 B \\ \multicolumn{6}{c}{1-Decanol} & 1273 & 1272 & n.d. C & 0.24 B & 0.15 B & 0.40 B & 1.01 A & 4.14 A & 2.8 A & 8.3 A \\ \hline \hline \end{tabular}
\end{table}