Scholarly record

EFFECTS OF GRAPE SEEDS FLOUR ADDITION ON WHEAT FLOUR DOUGH RHEOLOGICAL PROPERTIES

MSc. Eng. Madalina Iuga, Assoc. Prof. Dr. Eng. Silvia MironeasA, Dr. Eng. Dumitru Zaharia, Assoc. Prof. Dr. Eng. Sorina Ropciuc, Prof. Dr. Eng. Costel Mironeasa

Abstract

Grape seed flour (GSF) is a viable ingredient used in bread-making to improve its nutritional value. Wheat flour bread is the most consumed bread, mainly produced from white flour which has a reduced nutritional value. In this study GSF from white wine pomace, at different particle sizes was used in wheat flour type 550 at levels from 3% to 9%. This type of wheat flour was of a strong one for bread making with a low deformation index which presented a low alpha amylase activity due to its falling number index value (354 s). The increasing of incorporation levels of GSF from 3 to 9% (w/w flour basis) led to a decrease of falling number index related to particle sizes. The effects of GSF incorporation in wheat flour on dough rheological properties were determined by using empirical and fundamental test methods. The rheofermentometer device was used as empirical method in order to investigate dough rheological properties during fermentation process, gas retained capacity, all these being essential for the final bread volume. The results showed that the retention gas coefficient increased significantly with GSF levels increase from 3% to 9%, with significant differences of the impact of particle size on rheological properties during fermentation. Regarding the fundamental test methods, the frequency sweep tests and temperature sweep tests were applied by using a Haake dynamic rheometer. The linear viscoelastic region (LVR) of wheat-grape seed composite flour dough was evaluated by performing a strain sweep (0.01%-10%) at standard frequency of 1 Hz. The results showed that the dynamic rheological parameters, the storage modulus (G'), the loss modulus (G'') and the loss tangent (tan ?) were affected by the particle size and addition level of GSF. Also, the GSF addition influenced the thermal properties, initial and final gelatinization temperatures of wheat-grape seeds flour dough.

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