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Production of Novel Rice Flour Fractions
mm
by Michael Southan
February 2006 RIRDC Publication No W05/196 RIRDC Project No BRE-3A
Commercial rice flour produced in Australia is differentiated by range of particle size and physical grain type. However, large variations in flour performance could exist if the variety mix in the long grain and medium grain classes significantly changes. The physico-chemical properties of rice flour produced from individual varieties has not been investigated. Substantial new market opportunities for the rice industry could be exploited by understanding the performance of individual rice varieties in the flour milling process and marketing rice flour more specifically by matching the functional properties of the rice flour to the requirements of existing and new rice food products.
The objectives of this project were to:
Amaroo, Doongara,
Illabong and Langi were milled on the BRI Australia Pilot Mill to flour
with a particle size of less than 100 µm. Doongara produced the greatest
amount of flour with an average flour yield of 80.9% compared with Illabong
at 55.8%, Amaroo at 53.3% and Langi at 47.1% flour yield.
The physical and functional properties of the flour streams were different. 1st break flour of Doongara was coarser than the flour from Amaroo, Illabong and Langi but for the reduction flours Doongara flour was finer than Amaroo, Illabong and Langi.
Amaroo had the highest level of starch damage across most of the flour streams and Illabong the lowest. 1st break roll flours for all varieties across both seasons had the highest protein contents.
Doongara and Amaroo 1st break roll flours had the highest oil levels. Flour paste viscosities for cooked flours for 1st break flours from Amaroo and Doongara were lower than for the last reduction roll (F) flours. These differences in viscosity were not due to differences in protein content of the flours. Doongara flours were higher in amylose content than Amaroo flours and the amylose content and cooked flour textures for both varieties increased with increasing number of grinding passages.
The break roll flours which are only a small proportion of the total flour produced in the milling process have substantially different functional properties from the reduction flours. All these properties make the break flours very attractive as high value rice flours with potentially improved nutritional and functional properties for specific food applications.
These new flour types will potentially increase the value of the rice industry by expanding the rice value adding chain. Currently, rice flour production is approximately 40,000 tonnes per year. If sales or value of rice flour could be doubled, just by supplying new types of flour for new products the added value could be equivalent to $30 million.
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