Fatty acid composition, rheological and thermal properties of butter from sheep's and omega-3 cow's milks

In this study, the compositional, rheological, thermal and textural properties of omega-3 cow's butter (OCB), conventional cow's butter (CCB) and sheep’s butter (SB) were evaluated. The fatty acid composition of SB showed a relatively high content of the short chain fatty acids (SCFA) compared with that of cow's butters and higher levels of CLA and omega 3 fatty acids in OCB were observed. Regarding to the firmness, at refrigeration temperature (5 °C), SB was much firmer than CCB and OCB, but as a function of temperature, it was softened much quicker. However, at temperatures around 18°C it was already softer than the latter. From dynamic rheological data, it was found that butter samples display solid-like viscoelastic behavior since the values of G ׳ were much higher than those of G″ with a low dependence on frequency. The values of G ׳ and G″ also decreased in butters containing more percentage of unsaturated fatty acids. The temperature effect on the viscosity followed an Arrhenius-type relationship and OCB had a less activation energy than others, indicating that the butter containing high SCFA was more sensitive to temperature changes. Through differential scanning calorimetery, the thermal behavior of the butters during melting was analyzed.