Quality evaluation of OS wheat cultivars

The quality of wheat is to large extent controlled by the quantity and quality of the gluten protein. A variety of tests exist which indirectly estimate the quantity and quality of the gluten in wheat and flour. These methods include manual physico-chemical tests such as SDS sedimentation volume and the Zeleny test, and instrumental rheological methods such as the farinograph, mixograph, alveograph and extensograph. For breeding purpose, it would be important to have a fast and reilable method for gluten quality selections. A rapid method for determining both the quantity and quality of wet gluten is gluten index method which propose by Perten. This test involves preparing gluten from wheat or flour using the Glutomatic instrument. In this study, we determined the gluten index and various wheat quality parameters of OS winter wheat cultivars and there relationship during three years. Quality characteristics: grain protein content, Zeleny sedimentation test, wet gluten, gluten index, farinograph and extensograph properties of OS wheat cultivars were evaluated of 15 winter wheat cultivars selected at Agricultural Institute, Osijek, Croatia. The means ranges of variability and correlation of quality parameters determined on wheat samples from 1996, 1997 and 1998 harvest years. The total protein contents of OS wheat cultivar ranged from 11.82 to 13.54% (cultivar Sofija and Golubica, respectively). Sedimentation value ranged from 26.5 to 67.0 ml (cultivar Edita and Golubica respectively). The quantity of gluten expresed as wet gluten ranged from 24.5 to 37.2% (cultivar Sofija and Golubica, respectively). The gluten index as a quality measure of gluten indicated that 80% investigated OS wheat cultivars were bread ones. The gluten index in these cultivars varied between 60 to 90. Other cultivars which had gluten index >90 possessed strong gluten and were used as improvers. The lowest variability in determinate parameters of all cultivars was for total protein content. Good positive correlation was found between total protein and wet gluten, sedimentation value and many pharinographic properties. Wet gluten and sedimentation value and many pharinographic properties were good correlated. Gluten index was correlated positively with area, extensographic resistance and ratio resistance/ extensibility. Results of this investigation have shown that Gluten index is a simple and rapid method that can give more information about quality of wheat gluten than wet gluten determination only.