## Results  
### Volatile Arroma Composition  
From the GC-MS analysis of clear and cloudy juice produced from McIntosh (Figure 1) and Honeycrisp (Figure 2) apples, the 14 most abundant volatile aroma compounds were identified (Table 1). The volatile compounds from McIntosh juice were composed of about 42% aldehydes,37% esters, and 19% alcohols (Figure 3A). The major aldehyde detected in McIntosh juice was 2-methyl-4-pentenal (38.4%) with a minor content of (E)-2-hexenal (3.4%) (Figure 3A). The major esters detected in McIntosh juice included ethyl butanoate, butyl butanoate, hexyl butanoate, and 2-methyl butyl acetate, which contributed 11.8%, 8.1%, 7.8%, and 2.8% of the total volatile compounds, respectively (Figure 3A). Unidentified branched-chain alcohol and 2-hexen-1-ol, which comprised 12.6% and 6.0% of the total volatiles, were the major alcohols detected in the McIntosh juice (Figure 3A).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Volatile Compounds**} & \multirow{2}{*}{
\begin{tabular}{c} **Retention** \\ **Time (min)** \\ \end{tabular} } & \multicolumn{2}{c}{**Experimental**} & \multirow{2}{*}{**Odor Property**} & \multirow{2}{*}{**Odor Threshold**} \\  & **Time (min)** & & **Retention** \\  & **Index (RI) a  & **Odor Property** & **(mg/L)** \\ \hline \multicolumn{5}{c}{_Esters_} \\ Ethyl acetate & 6.83 & 898 & Ether like [2] & 7.50 [12] \\ Ethyl butanoate & 10.15 & 1049 & Sweet fruity [13] & 0.001 [14] \\ Butyl acetate & 10.91 & 1087 & Sweet fruity [13] & 0.066 [12,14] \\
2-Methyl butyl acetate & 11.83 & 1137 & Fresh [13] & 0.011 [14] \\ Butyl butanoate & 13.46 & 1233 & Fresh [13] & 0.10 [14] \\ Hexyl acetate & 14.32 & 1287 & Sweet fruity [13] & 0.002 [14] \\ Hexyl butanoate & 16.41 & 1433 & & \\ _Aldehydes_ & & & & \\
2-(E)-hexenal & 13.64 & 1244 & Green apple like [2] & 0.011 [12] \\
2-Methyl-4-pentenal & 15.49 & 1367 & Desirable, green grass, fruity [15] & \\ _Alcohols_ & & & & \\ Ethanol & 7.88 & 944 & Sweet [2] & 716 [12] \\ (Z)-2-hexen-1-ol & 11.09 & 1096 & Fresh leaf green [13] & 0.07 [16] \\ Unidentified branched-chain alcohol & 16.56 & 1444 & & \\ _Acids_ & & & & \\ Ethyl & 10.43 & 1063 & & \\
2-methylbutanoic acid & 10.43 & 1063 & & \\ _Hydrocarbon_ & & & & \\ Alkene I & 13.16 & 1214 & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Major volatile compounds isolated from clear and cloudy apple juice of McIntosh and Honeycrisp apples.  
Figure 3: The relative abundance of volatile compounds identified in fresh, clear, and cloudy apple juice from McIntosh (**A**) and Honeycrisp (**B**) apples, as well as from whole McIntosh (**C**) and Honeycrisp (**D**) apples stored for 4 months under controlled atmosphere (CA) or regular atmosphere (RA) conditions and harvested at commercial or late maturity stage. The value for each bar represents the mean of 48 samples each with three biological replicates.  
The aroma volatiles in Honeycrisp juice were dominated by esters, which comprised 78.9% of the total volatiles followed by aldehydes (11.8%) and alcohols (8.7%) (Figure 3B). The major esters found in Honeycrisp juice were butyl acetate (31.3%), 2-methyl butyl acetate (22.9%), ethyl acetate (10.3%), and hexyl acetate (8.0%) (Figure 3B). As in McIntosh, the major aldehyde in Honeycrisp juice was 2-methyl-4-pentenal (10.4%) with a minor amount of (E)-2-hexenal (1.4%) (Figure 3B). The unidentified branched-chain alcohol (5.7%) and 2-hexen-1-ol (2.1%) were the major alcohols detected in Honeycrisp juice. In both cultivars, ethanol was a minor constituent, accounting for \(<\)1% of the total volatile compounds (Figure 3A,B).