## 3 Results and Discussion
### Volatile Analysis
#### 3.2.1 Effects of Storage, PEF Processing, and Cuts on Volatile Composition  
PEF-Treated Chilled Samples  
Principal Components Analysis (PCA) provides an overview of how storage, PEF processing, and different meat cuts interacted in a 2-dimensional product space. Figure 4a shows that different meat cuts did not have any significant effect on volatile composition. Interestingly, factor 1 (F1) differentiated control samples from PEF processed samples stored for 7 days. In addition, factor (F2) differentiated the samples in terms of effects of storage. Figure 4a explained 66.74% variance and showed that PEF-treated samples were separated along F1 from control samples. Positive scores along F1 were correlated with PEF processed samples stored for 7 days. Chilled samples that were subjected to both PEF processing and 7 days storage were associated with 2-heptanone (3), 3-methyl-butanal (6), hexanal (8), heptanal (9), 2-ethylfuran (12), pyridine (15), methyl-pyrazine (17), 2-ethyl-3-methyl-pyrazine (18), 3-ethyl-2,5-dimethyl-pyrazine (19), 3,5-diethyl-2-methyl-pyrazine (20), dimethyl disulphide (22), and dimethyl trisulphide (24). Pyrazines are generally associated with non-enzymatic browning, which generally possesses roasted, nut-like notes [11]. Aldehydes like 3-methyl-butanal (6), hexanal (8), and heptanal (9) were another major class of volatiles that was associated with both PEF processing and 7-days storage. The presence of aldehydes has been associated with lipid oxidation in meat. For example, hexanal occur in meat during flavour formation and lipid oxidation and heptanal arises from the oxidation of oleic acid [12; 13]. The volatile, 3-methylbutanal (6) described as being malty and fatty has been reported to be an important volatile compound in cooked beef [12] and goat [14] that can contribute to roasted beef flavour [12]. In addition, [PERSON] et al. [15] reported that 3-methylbutanal was found in high concentrations in longer aged hands. Sulphur volatile compounds are derived from sulphur containing amino acid degradation [16]. The potent sulphur-containing compounds can be formed from the  
Figure 4: Principal Component Analysis Biplot of volatile profiles of PEF and non-PEF treated cooked chilled with 66.74% variance explained (**a**) and frozen-thaved with 77.56% variance explained (**b**) lamb meat of different cuts. Sd = Shoulder; Rib = Rib; L = Loin; K = Knuckle; R = Rump; S = Shank; T = Topside; C: control; P: PEF; 0 = 0 days storage; 7 = 7 days storage/post-processing storage. VOC codes for Figure 4a correspond to Supplementary Table S2 for chilled samples, and codes in Figure 4b correspond to Supplementary Table S3 for frozen samples. reaction between cysteine and ribose when meat is cooked. Dimethyl sulphide, dimethyl trisulphide, and dimethyl disulphide have been detected in beef [17]. In contrast, negative scores along F1 were correlated with control samples that were stored for 7 days. Control samples that were subjected to 7 days storage were shown to be associated with 2,3-octanedione (2), 2-nonanone (4), 2-methyl-butanal (7), benzaldehyde (10), nonanal (11), 2-vinylfuran (13), 2-pentylfuran (14), pyrrole (16), thiophene (21), and 2-furanmethanethiol (23). Similarly, 2,3-octanedione and 2-pentyl-furan have been reported in chilled aged beef muscles for 7 or 14 days [18]. These volatiles are often associated with lipid oxidation and are affected by enhancement and aging in the various muscles. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [5] also reported that the relative concentration of the lipid oxidation product (2-pentylfuran) increased in non-PEF treated (control) shoulder and rib cuts of lamb meat with increased storage time. PEF processed and control chilled samples that were stored at 7 days storage had positive scores along F2 that were associated with 1-hexanol (1) and 2-methyl propanal (5), 2,3-octanedione (2) and thiophene (21).