The effect of dietary omega-3 fatty acids with specific reference to Echium seed oil on pork quality
Van Wyngaard, Barbara Elizabeth
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The objective of this study was to determine the effect of Echium seed oil, together with other n-3 containing oils, on the levels of long chain n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA), eicosapentanoic acid (EPA) and docosahexaenoic acid (DHA) deposited in the animal tissue. Further, to determine the effect of these experimental diets on animal production and meat quality under commercial production conditions. The study also included the manufacturing of processed meat products from experimental animals and determining the chemical and sensory stability of such products. Sixty Landrace x Large White crossbred pigs, with an average weight of ± 30 kg, were randomly divided into five treatment groups. These treatments comprised of a control diet, supplemented with 1% palm oil (BergaFat HPL-160) and four experimental diets supplemented with one of 1% soya oil, 1% linseed oil, 1% fish oil and 1% Echium oil. Pigs were fed until the average live weight was ± 110 kg. Growth performance (weight increase, ADG and FCR) showed no significant differences between treatments. The only differences in carcass characteristics were the linseed treatment which demonstrated a smaller shoulder circumference and thinner backfat thickness compared to the other treatments. Backfat from the control had the best technological properties as it had lower levels of PUFA and a lower double bond index (DBI) compared to the other treatments. The Echium treatment had the highest levels of stearidonic acid (SDA) (mg/100g tissue) in the back-, belly fat and muscle. In all three these tissues the Echium treatment also had higher levels of EPA and DPA, however it was still significantly lower than the levels in the tissue of the fish oil treatment. In both the back- and belly fat, the Echium had no effect on the levels of DHA, however in the muscle it did increase the levels of DHA. The levels of EPA, DPA and DHA was the highest in the fish oil treatment, however the Echium treatment had significantly higher levels than the other treatments. There were no problems with lipid stability in either the fresh or frozen pork and values were far below the threshold value. A trained panel was unable to detect any sensory differences between the Echium treatment and the control. Processed meat products are more susceptible to lipid oxidation and increasing the levels of PUFA normally causes accelerated rancidity problems. In general pork bangers had very high TBARS and the Echium treatment had the highest values. The high TBARS values had a clear influence on the sensory properties as the bangers from the Echium treatment scored the lowest for taste, aftertaste and overall acceptability. Bacon did not have any problems with either the lipid stability or sensory properties, due to the anti-oxidative action of nitrite and the preservative effect of smoking. TBARS values for all treatments from the salami were all below the threshold value were rancidity could be detected. Under the US Food and Drug Administration guidelines the meat from Echium oil treatment in this study can be labelled as a source of EPA, DPA and DHA as it contributed more than 10% to the daily recommendation. Pork products (bangers, bacon and salami) manufactured from meat of the Echium treatment can be labelled an excellent source of total n-3 PUFA as they contribute 91.5, 34.08 and 41.1% respectively. Therefore, pork and pork products from animals fed Echium oil can be considered functional foods as it will have a positive effect on human health. South African pig producers may therefore consider using Echium oil to improve the healthiness of their pork and marketing it as a health food.