# Effect of Seasoning Addition on Volatile Composition and Sensory Properties of Steved Pork
## 3 Results and Discussion
### Relationship between Sensory Evaluation and Odour-Active Compounds  
PLSR was employed to establish the relationship between the five sensory descriptors of the fresh and stewed pork and the odour-active compounds analysed by GC-MS/O and GC \(\times\) GC-TOFMS, and the correlation coefficient between them was expressed in the heat map. As shown in Figure 5a, most of the \(X\)-matrix (contribution ratios of the odour-active compounds) and \(Y\)-matrix (intensities of the sensory attributes) are loaded around the circle (\(r^{2}=100\%\), \(r^{2}=\) represent the degree of interpretation). The model quality (Q\({}^{2}=0.846\)) \(\geq 0.50\) indicated that they were well explained by the PLSR model. The first two components explained 74.0% of \(X\)-matrix and 92.7% of \(Y\)-matrix. The dots corresponding to sample SP\({}_{1}\) and SP\({}_{2}\) had overlap in the second quadrant, and the samples points of SP\({}_{3}\), SP\({}_{4}\), SP\({}_{5}\) and SP\({}_{6}\) were close in the fourth quadrant, and as well as FP was  
Figure 4: The odour sensory profiles of the fresh and stewed pork. Asterisks indicate significant (**\(p\leq 0.01\); ***\(p\leq 0.001\)) differences of means in descriptor intensities. FP, fresh pork; SP1, stewed pork with water; SP2: stewed pork in water and salt; SP3: stewed pork in water, salt and spices; SP4: stewed pork in water, salt, spices and soy sauce; SP5: stewed pork in water, salt, spices, soy sauce and sugar; SP6: stewed pork in water, salt, spices, soy sauce, sugar and cooking wine.  
found in the third quadrant. So, the fresh and stewed pork samples can be divided into three group and this result was consistent with previous PCA plots (Figure 2a). According to Figure 5a,b, it can be observed that SP\({}_{3}\), SP\({}_{4}\), SP\({}_{5}\), and SP\({}_{6}\) were characterized by soy sauce, caramel and spicy odour because of their short distance, and the three aroma attributes aforementioned were positively correlated with pentanal, benzeneacetaldehyde, 1,8-cineole, 1-hydroxyprom-2-one, D-limonene, ethyl acetate, eugenol, methanethiol, and dimethyl trisulfide with a high correlation coefficient (0.60 \(\leq\) r \(\leq\) 0.92). On the contrary, the soy sauce, caramel and spicy notes located in the right side of the loading plot were strongly and negatively correlated with some aldehydes (heptanal, nonanal, (_E_)-oct-2-enal, (_E_)-non-2-enal, (_E_)-dec-2-enal, (_E_,_E_)-2,4-nonadienal, undec-2-enal and (_E_,_E_)-2,4-nonadienal) and unsaturated alcohols like (_E_)-oct-2-en-1-ol. SP\({}_{1}\) and SP\({}_{2}\) on the upper left side of loading plot were mainly descriptive fatty and meaty odour, which were in accordance with the descriptive sensory analysis. These two attributes were highly associated with hexanal, oct-1-en-3-ol and 2-pentylfuruan. Moreover, FP was located far from these flavour attributions and most volatiles, which indicated that there was not the unique flavour of the fresh pork.  
Figure 5: _Cont_.  
Figure 5: _Cont._  
Figure 5: (**a**) PLSR loading for the odour attributes (Y variables) and the odour-active compounds of the fresh and stewed pork (X variables). (**b**) Heat map illustrating the Pearson correlation between descriptor intensities and proportion of OAVs of the odour-active compounds calculated by PLSR. The green circle dots represent 7 pork samples, the red circle dots represent 5 aroma attributes and the purple triangle dots represent 29 odour-active compounds.