Dynamic viscoelastic characterisation of ostrich-meat yor (Thai sausage) following pressure, temperature and holding time regimes.

Ostrich-meat yor (Thai sausage) was pressurized at 200, 400 and 600MPa, with 40 and 50°C for 40 or 60min, subsequently, the products were assessed by stress control rheometry. Two types of viscoelastic measurement were made. The first was an oscillatory analysis performed at a frequency range of 0.01-10Hz using a stress of 30Pa. Secondly, creep and recovery testing was performed with an initial load of 30Pa for 300s, unloaded recovery 900s. Finally, the products were subjected to sensory evaluation using a 9-point hedonic scale. To support the rheological measurement, SDS-PAGE electrophoretic analysis was also applied. The viscoelastic characterisation of all treated ostrich-meat yor showed that G' was larger than G″ with small tan δ values (0.23) and the difference between G' and G″ of each plot was relatively one log cycle. These indicated solid-like behaviour with the predominance of an elastic component. Whereas all creep curves of the treated samples were best characterised by a four-element "Burgers" model in which the J(0) data and retardation time (λ(ret)) suggested that increasing pressure levels, temperature and holding time significantly affected the viscoelastic properties of the samples. The electrophoregrams indicated that these structural changes which might be associated with the formation of hydrophobic interactions and disulphide bonding. Most sensory attributes of the pressure treated products received higher scores than conventionally steamed products.