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Rheological Characterization of a new cereal called Tritordeum
Tritordeum is a new natural cereal. It is combination of durum wheat (Triticum durum) and wild barley (Hordeum chilense) native to Chile and Argentina. It is the first newly-created cereal suitable for human consumption. Tritordeum is not a GMO and has numerous nutritional benefits (lower content in immunogenic gliadins which are associated with celiac disease, higher level of lutein and dietary fibers compared to standard wheat). It is also suitable for a wide range of cereal-based products (bread, biscuit…). First commercialized in 2006, the rheological properties of Tritordeum are not fully understood yet which makes the quality control of this cereal very complicated. This study aims to evaluate the rheological properties of Tritordeum flour thanks to the Alveolab instrument.
MATERIAL AND METHODS
Agrasys S.L. (the company that owns the exclusive rights of Tritordeum exploitation) supplied three samples of Tritordeum flours with different baking qualities: (Figure 1)
• Flour A gives excellent baking results
• Flour B is acceptable
• Flour C gives unacceptable results in bread application
The baking test used to analyze those flours is a little different compared to the standard baking test for wheat flour. The reason is that the Tritordeum gluten network is weaker than standard bread wheat gluten. Based on the baker’s experience in bread making, it was observed that a lower mixing speed and less hydrated dough enables the baker to achieve better gas retention and less relaxation.
These samples were tested according to both the Alveograph AACC 54-30.08 standard method and a new one called "Tritordeum protocol". This method is conducted at 45 % hydration with a slower mixing speed (40 rpm instead of 60). All analyses were made in duplicate to evaluate the repeatability of the new method. The repeatability of the results is evaluated thanks to the standard deviation between two results from the same flour.
RESULTS & DISCUSSION
The results show that both protocols allow the assessment of Tritordeum flour. The samples are well discriminated (Figures 2 and 3) and the results are consistent with the baking quality of the flours. The higher the W value, the better the baking quality; and the higher the Elasticity Index (Ie), the better the baking quality (Figures 4 and 5 respectively).
However, the Tritordeum protocol gives results closer to the baking performance:
• Since Tritordeum flour contains less gluten protein, reducing the mixing speed creates less damage of the weaker gluten network ("W" values are between 107 and 227 instead of 38 and 135). Consequently the results are more representative of the quality of the tested flour.
• The new protocol gives better repeatability (Table 2): this means standard deviations between 2 runs of the same flour are on average 3 times lower: 2.6 with the Tritordeum protocol instead of 8 with the standard protocol ("W" value). This can be explained by the fact that the dough during the test is very sticky and difficult to handle with the standard protocol but much more consistent and easier to handle with the Tritordeum protocol.
• Finally, the results are more discriminated (better visual separation of the curves from different samples) and so more in line with the baking quality of the flours. For example, the higher the "Ie" parameter, the better the behavior of the flour during process (7.6% for an unacceptable baking quality flour, 37.6% for an excellent baking quality flour).
Rheological properties of Tritordeum doughs can be evaluated and the baking quality of such products can be predicted thanks to the new Alveograph "Tritordeum protocol". This protocol works with 45% hydration (15% basis) and a lower mixing speed. It has been developed to reduce gluten damage during the kneading step and to improve dough consistency, leading to higher repeatability of the test and better discrimination of flours. "Tritordeum protocol" is recommended as the protocol to analyze Tritordeum flours.