Oxygen transfer rate, can play an important role in the scale-up and economy of many microbial processes and values of the volumetric oxygen transfer coefficient (k(L)a) for specific fermentation culture media need to be evaluated and correlated to obtain the appropriate design tools. The purpose of this work was to determinate the values of k(L)a in yeast broths (Trigonopsis variabilis) in a mechanically-stirred, sparger-aerated and baffled reactor, the most common fermenter type, over a wide range of superficial air velocities impeller rotational speeds and geometric parameters. Three different mixing vessels (2, 5 and 15 litres) were used in order to consider the effect of the fermenter scale-up on k(L)a. Once k(L)a data are obtained, several empirical and theoretical correlations were used to fit the experimental data. A new correlation is proposed (k(L)a=3.2.10(-3)(P/V)(0.35) (U-sg)(0.41)) based on the power input per unit volume of liquid (P/V) and the superficial gas velocity (U-sg). The correlation improves the prediction of k(L)a values in culture media with respect to other generic correlations, mainly because early correlations were developed for strong coalescent and non-coalescent fluids, whereas the medium used in this work and in most the yeast broths behaves as a typical Newtonian, slightly non-coalescence fluid, due to the moderate presence of mineral salts.