Milling method can improve functional properties of rice flour, study

Rice is increasingly being used in processed foods such as bread, tortillas, beverages and puddings in part to respond to rising demand for gluten-free products.

But knowledge about the functional properties of different rice flours significantly lags that of wheat flour.

A team from the US Agricultural Research Service and the Dale Bumper National Rice Research Centre found that the method for milling rice flour may significantly alter the functional properties of rice-based foods.

Texture tests Writing in an early online edition of the Journal of Food Science, the team said that making rice bread with a commercially produced long-grain rice flour resulted in a poor texture.

The bread "collapsed more than loaves made from pin milled flour" , they report.

The bread had "a lower specific volume and undesirable texture", including large holes in the slices.

The difference emerged even though the commercial rice flour had similar amylose and protein contents to flour made in the researchers' laboratory by pin and Udy milling of the same second-head long-grain rice.

The better result with pin-milled flour is thought to be thanks to the more uniform particle size.

In the other two flours tested, commercial rice flour and Udy milled flour, " the excessive amount of fines affected their functional properties", reported Kadan and his colleagues.

The commercial flour was milled by a proprietary method using a combination of a hammermill, 1st pass and a turbo mill, 2nd pass.

"The milling methods have important effects on the functional properties of rice flour and hence their usage in novel foods," concluded the researchers.

"The pin mill imparts more uniform particle size and therefore is more suitable for developing novel rice foods."

Gluten-free market Novel rice foods make up a sizeable portion of the fast growing gluten-free foods market.

In 2001, it was valued at $210m, and has grown at a compound annual growth rate of 27 percent since then, to reach $696.4m in 2006.

The market is estimated to continue to grow at 25 percent per year until 2010.

However even though awareness of coeliac disease is increasing, technical challenges remain a major barrier to the development of successful gluten-free products.

This, and a lack of investment in product development, is holding back the market's potential, according to a Euromonitor report out last year.

"For mainstream manufacturers and retailers, it is important to realise that foods for intolerances are no longer niche," said Simone Baroke, health and wellness products analyst at the firm.

Producing high margin specialist foods may also help users of rice ingredients recoup the rising costs of rice, already up 66 per cent in the first three months of this year.

Source: Effects of Milling on Functional Properties of Rice Flour R.S. Kadan, R.J. Bryant, and J.A. Miller Published article online: 11-Apr-2008 doi: 10.1111/j.1750-3841.2008.00720.x