Characterization of common wheat flours through glutopeal analysis and kieffer test

Many rheological tests have been proposed to predict flour performance during baking. The most important procedures are performed by using well known equipment such as Farinograph, Estensograph or Alveograph, which provide reliable results, well correlated with the quality of the final products. Despite the diffusion of these methods, some other rheological tests have recently been proposed with the aim of reducing the sample amount and, in some cases, also the testing time. The focus of the present research is to evaluate the possibility of using two different procedures, the GlutoPeak and the Kieffer tests, as alternative approaches to characterize flours in particular when samples are available only in small quantities, as in breeding programs. GlutoPeak gives a measure of protein aggregation during intense mechanical action, whereas the Kieffer test provides information on the stretching properties of dough. In this research, 87 samples of wheat flours, provided by five different industrial mills and characterized by different final uses, were analyzed. Flours were evaluated both by means of empirical conventional methods (Farinograph, Estensograph, Mixolab and Alveograph) and through the other two novel approaches. The results of the conventional tests indicated a large degree of variability in the rheological properties of the flour samples. In particular, the farinographic water absorption ranged from a minimum of 48.5% to a maximum of 63.2%, the stability from 2.5 min to 28.8 min, the alveographic W from 40x10-4 J to 494x10-4 J and P/L from 0.24 to 1.45. As regards the estensographic test, considering the curves after 90 min, samples were characterized by maximum resistance values between 48 and 897 BU and extensibility between 38 and 222 mm. Similarly, a wide variability characterized the results of GlutoPeak and Kieffer tests. Maximum torque of GLutoPeak curve, index of gluten ability to aggregate, were significantly correlated (p<0.05) to the flour absorption capacity and stability obtained with the Farinograph. Significant correlations (p<0.05) were also obtained between the maximum force registered during the elongation test performed with the Kieffer device as well as both estensographic total energy and maximum resistance. The overall results indicate that the Glutopeak and Kieffer tests can be used to integrate the information obtained by conventional rheological tests to better define flour baking aptitude or even replace them in breeding programs, where a throughput improvement is needed and samples are available only in small quantities.