The stability of fatty acids in yoghurts produced from bulk milk samples intentionally selected according to dairy production systems

The fatty acid (FA) composition of milk fat can be positively influenced by the modification of dairy farming and the possible selection of raw material for processing. The question arises as to whether the benefits of a better FA composition will be maintained even after processing dairy products. Thus, the aim was to obtain a more favourable FA composition by a targeted selection of cow's milk (grazing vs stabled herds) and then compare FAs of milk and fermented product (yoghurt). Bulk tank milk of grazing herds had significantly better FA composition than milk of stabled herds (for example, C16:0 28.07% vs 32.27%, P < 0.001; C18:3n-3 0.83% vs 0.41%, P < 0.001; C18:2 cis-9, trans-11 (conjugated linoleic acid; CLA) 1.02% vs 0.41%, P < 0.01). The differences between the FAs in milk and yoghurt samples were negligible (in relative values from 0.04% to 5.21%). The correlations between milk and yoghurt for nutritionally important FAs were high, from 0.925 0 (C18:2n-6) to 0.998 8 (CLA; both P < 0.001). The minimal effect of milk fermentation on the original FA composition of milk fat was found. In conclusion, systematic selection of raw cow's milk or modification of farming conditions can also provide a nutritionally desirable composition of final dairy products.