## 3 Results and Discussion
### PLSR Correlations between Chemical Composition and Sensory Perception
#### 3.4.2 Frozen Samples  
The correlation biplot (Figure 6b) of PEF treated frozen lamb samples showed that juicy and meaty were associated with C14:0, C16:1, C20:0, and C24:0 that had high positive loadings along Dimension 2. Similar to chilled samples, the majority of saturated fatty acids were positively correlated with positive flavours like juicy and meaty. In accordance with the present results, saturated fatty acids such as C14:0 were associated with positive sensory perception (e.g., juiciness) of Korean Hanwoo beef frozen at \(-20\)\({}^{\circ}\)C [50]. Livery and bromed were associated with PUFA, MUFA, n-6, 18:1 cis-9, and 20:2 (n-6) on the negative loadings of Dimension 2. High concentrations of unsaturated fatty acids has been reported with formation of undesirable off-odours and flavours in meat due to lipid oxidation [51]. The presence of the aforementioned unsaturated fatty acids was also reported to be associated bloody, metallic, and livery flavours in beef loin samples [52]. The correlation biplot (Figure 6b) of PEF treated frozen lamb samples showed that amino acid measurements for frozen samples were correlated with oxidised, bromed, and livery flavour that had high negative loadings along Dimension 1. Browned and livery flavours were correlated with glycine, histidine, and proline. Glycine is an important compound in initial Maillard intermediates, which contribute to the formation of browned flavour in meat [53]. Proline has also been associated with browned flavour but is formed through the Amadori pathway [53]. In contrast, histidine plays a huge role in myoglobin structure and function. More specifically, distal histidine may interact with bound oxygen, which alters myoglobin structure and stability [54]. These changes are correlated with livery flavour, an off-flavour in beef [38]. Oxidised flavour was correlated with the presence of threonine, isoleucine, tyrosine, and phenylalanine. Interestingly, an increase of the aforementioned amino acids was shown to be associated with off-tastes such as acidity in dried meat products [55] and bitterness in some meat cuts [56]. The correlation biplot (Figure 6b) of PEF treated frozen lamb samples showed that livery and browned flavours were associated with flavour volatiles like dimethyl disulphide, 2-methyl-butanal, and heptanal, similar to chilled samples. Dipropyl disulphide and dipropyl trisulphide resulted in sharp rancid flavour and pungent smell in frozen pork dumplings [57]. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [27] further found that aldehydes like 2-methylpropanal, 3-methylbutanal, and 2-methylbutanal contributed negatively to lamb flavour because of their association with lipid oxidation [52], similar to present results. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [5] reported that browned and the livery flavours were correlated with PEF treated frozen-thawed shoulder cut on the 0 days of storage that had high concentrations of 2-heptanone and 2,3-octandione. Furthermore, oxidised flavour was mainly associated with 2-pentylfuran, and 2-ethyl-3-methyl pyrazine. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [5] also reported that PEF treated frozen-thawed shoulder cut of lamb was associated with 2-pentylfuran and 2-methylpropanal and 3-methylbutanal in loin cut stored for 7 days that were correlated with oxidised flavour. A correlation biplot showing how fatty acids, amino acids, and volatile composition of PEF treated frozen lamb samples were correlated to sensory attributes is shown in Figure 6b. Meaty and juicy attributes had high positive loadings along Dimension 1. These attributes were mainly associated with the presence of volatiles, especially 2-nonanone, 2-pentylfuran, pyrrole, methyl pyrazine, 2-ethyl-3-methyl pyrazine, and thiophene, instead of fatty acids. This is because the principal reaction in frozen raw and cooked meat is lipid oxidation that releases volatiles that contribute to flavour [37].