## 3 Results and Discussion
### Odorant Addition Experiment  
A series of controlled odorant addition experiments was conducted to further validate the contribution of key differential aroma active compounds. As indicated by the QDA results (Figure 1), the primary flavor differences between FPJ0 and the frozen-treated samples were characterized by grassy, fruity, floral, and woody attributes. Consequently, these four sensory attributes were selected for evaluating the aroma profiles of the samples, with the fresh sample FPJ0 as the control. The three frozen-treated samples were utilized as carriers for odorant addition experiments. Compound selection was based on two essential criteria: (1) OAV and VIP scores exceeding 1.0, and (2) concentration changes after freezing that correlated with the observed alterations in the aroma attributes mentioned above. While nonanal and hexanal satisfied the first criterion (OAV/VIP > 1), their concentration  
Figure 5: OPLS-DA analysis of FPJ and frozen juices. (**A**) Cross-validation of the OPLS-DA model. (**B**) VIP scores obtained from OPLS-DA analysis of FPJ and frozen juices. profiles showed a significant increase post-freezing, which contrasted with the depletion pattern of our target compounds and the diminishing trends of the associated sensory attributes. Consequently, these compounds were excluded from subsequent analyses. Finally, three individual key aroma active compounds (hexanol, (_Z_)-3-hexen-1-ol and \(\beta\)-myrcene) and their mixtures were sequentially added to the frozen samples (FPJ\({}_{--}\)20 \({}^{\circ}\)C, FPJ\({}_{--}\)40 \({}^{\circ}\)C, and FPJ\({}_{--}\)80 \({}^{\circ}\)C) at concentrations corresponding to their natural differences from FPJ0. The results are shown in Figure 6. The addition of these volatiles remarkably enhanced one or more sensory attributes of the frozen-treated samples. For example, the addition of (_Z_)-3-hexen-1-ol resulted in a significant enhancement of grassy and fruity notes (_p_ < 0.001). Specifically, the grassy scores in three frozen-treated samples (FPJ\({}_{--}\)20 \({}^{\circ}\)C, FPJ\({}_{--}\)40 \({}^{\circ}\)C, and FPJ\({}_{--}\)80 \({}^{\circ}\)C) increased by 10.69%, 8.03%, and 8.04%, respectively. The intensity of the fruity attribute raised by 19.72%, 9.27%, and 11.55% after adding (_Z_)-3-hexen-1-ol, respectively. Additionally, the incorporation of hexanol into the frozen-treated juices also significantly increased the grassy attribute (_p_ < 0.001), with increases of 28.23%, 10.69%, and 12.53%, with the corresponding frozen-treated samples (FPJ\({}_{--}\)20 \({}^{\circ}\)C, FPJ\({}_{--}\)40 \({}^{\circ}\)C, and FPJ\({}_{--}\)80 \({}^{\circ}\)C) as controls, respectively. \(\beta\)-Myrcene, a volatile of interest for its woody characteristics, also resulted in significant increases in woody scores by 38.38%, 29.91%, and 13.15% in the three frozen-treated PJ samples, respectively. Further, the frozen-treated PJ samples with the three key aroma volatiles added (hexanol, (_Z_)-3-hexen-1-ol, and \(\beta\)-myrcene) resulted in scores of 5.24 (FPJ\({}_{--}\)20 \({}^{\circ}\)C), 5.25 (FPJ\({}_{--}\)40 \({}^{\circ}\)C), and 5.24 (FPJ\({}_{--}\)80 \({}^{\circ}\)C) for the grassy note; 2.53 (FPJ\({}_{--}\)20 \({}^{\circ}\)C), 2.54 (FPJ\({}_{--}\)40 \({}^{\circ}\)C), and 2.56 (FPJ\({}_{--}\)80 \({}^{\circ}\)C) for the woody note; and 5.65 (FPJ\({}_{--}\)20 \({}^{\circ}\)C), 5.64 (FPJ\({}_{--}\)40 \({}^{\circ}\)C), and 5.66 (FPJ\({}_{--}\)80 \({}^{\circ}\)C) for the fruity note. These scores represented increases of 40.07%, 20.34%, and 10.76% for the grassy note; 40.04%, 30.09%, and 14.64% for the woody note; and 19.3%, 8.88%, and 23.79% for the fruity note in the corresponding added groups. Compared to the fresh sample FPJ0, the added frozen PJs exhibited minimal differences in grassy, woody, and fruity notes. These findings indicated that (_Z_)-3-hexen-1-ol, \(\beta\)-myrcene, and hexanol could partly restore the grassy, fruity, and woody attributes of the frozen samples.