Differences between unfrozen and 2-years frozen pork were significant (Table 3) when
comparing the percentage of intramuscular fat (IMF) and concentrations of most individual
3
fatty acids in the IMF. The intramuscular fat of loin was significantly (P≤0.001) higher in 2-
years frozen than unfrozen pork. It could be due to the concentration of fat in muscle by water
losses that occur after thawing. On the other hand, the proportion of palmitic acid (C16:0),
stearic acid (C18:0), oleic acid (C18:1 n-9) and total saturated (SFA) and monounsaturated
fatty acids (MUFA) were significantly higher in 2-years frozen pork. However, proportions of
n-6 polyunsaturated fatty acid (PUFA), such as linoleic acid (C18:2) and arachidonic acid
(C20:4), and proportions of n-3 PUFA, such as α-linolenic acid (C18:3) and eicosapentaenoic
acid, EPA (C20:5), were significantly lower after freezing. Therefore, the total PUFA
percentage was lower in 2-years frozen pork. The muscle content of phospholipids (PL) is
relatively constant and contains mainly polyunsaturated fatty acids [11]. Awad et al. [12]
found that a considerable decrease in the PL content was evident as the frozen storage time of
muscle progressed. This drop can be accounted for the enzymic hydrolysis of PL
concentration during the frozen storage and it could be related to this drop in total PUFA
percentage.