One of the most important characteristic of technological quality of pork is lipidic profile. Meat products containing soft fat show quality defects, such as insufficient drying, oily appearance, rancidity development and lack of cohesiveness between muscle and adipose tissue on cutting. The aim of this research was to determine how dietary CLA supplementation of pigs affects the physical properties, fatty acid composition and melting and crystallization behaviour of fat in an attempt to explain the effect of elevated CLA levels on technological properties of backfat. For this, 48 (Large White x Duroc) gilts, with an average of 35 kg of body weight, were randomly distributed into four groups of twelve pigs each. The groups were then randomly assigned to one of the four dietary treatments that consisted of a control diet containing 1% sunflower oil (SFO), a diet containing 0.75% SFO + 0.25% CLA, a diet containing 0.5% SFO + 0.5% CLA and a diet containing 1% CLA.
Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ± 11% overall decrease in unsaturated fatty acids and a ± 5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ± 14ºC to ± 18ºC for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ± 26ºC for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ± 37ºC to ± 43ºC and ± 45ºC, respectively. The presence of β′-crystals of C18:0–C16:0–C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. The elevated CLA levels in subcutaneous fat resulted in improved technological properties of the backfat, as were demonstrated by an increase in backfat hardness, decrease in iodine value, increase in SFA, decrease in MUFA, increase in C18:0/C18:2c9c12 ratio.
It is concluded that the most important fat quality parameters are affected by 0.25% of dietary CLA inclusion. An inclusion level of 0.25% would be therefore considered as optimal from a fat quality point of view.
Bothma, C., Hugo, A., Osthoff, G., Joubert, C.C., Swarts, J.C. and de Kock, H.L. (2014). Effect of dietary conjugated linoleic acid supplementation on the technological quality of backfat of pigs. Meat Science 97; 277–286 http://dx.doi.org/10.1016/j.meatsci.2014.02.002