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Impact of rice varieties and milling processes on rice flour and final bakery products quality
S. BRYAN (1), O. Le Brun (2), M. Berra (2), G. Véricel (2), A. Dubat (2) (1) Chopin Technologies, Olathe, KS, U.S.A.; (2) Chopin Technologies, Villeneuve-La-Garenne, France.

The way rice is consumed is changing constantly. Originally it was only as cooked grain but now rice is also consumed in many other forms. For example, in Japan, rice and wheat flours are combined to create breads with lighter and moister texture. The food industry must adapt to the evolving consumer tastes. It must create new methods for the selection and quality control of rice products. The objective of this study is to contribute to the development of new methods by evaluating the impact of the milling process on both rice flour quality (composition, particle size distribution and rheological properties) and the final bread product quality (volume and hardness). Six rice samples (representing different varieties) were milled using two different processes (roll mills and jet mills). Samples were both tempered and untampered. The flours were analyzed for amylose content, particle size distribution and rheological behavior (using a Mixolab) plus the bread making potential of the finished flours. Mixolab and bread making tests were made using mixtures of rice (30%) and wheat (70%) flours. Amylose content varied from 12% to 32% and was mainly impacted by variety. Particle size was strongly dependent on milling and tempering combinations with average particle sizes varying from 43 µm from untampered dry jet milling to 130 µm from untampered roll milling. Specific bread volume varied from 3.5 ml/g to 4.1 ml/g and presented good correlation (r2 = 0.61) with dough stability (Mixolab C1-Cs). Bread firmness varied from 3000 g to 6000 g and is correlated (r2 = 0.50) with starch gelatinization (Mixolab C3-C2). In the end, these results confirm the necessity to control the rice flour production process to control final bakery product quality. Laboratory analysis, using devices like the Mixolab, are essential to achieve this objective.