White Rice Flour
What is White Rice Flour?
It is a flour produced from grinding polished white rice without the bran layer.
Rice flour is very common in parts of the world where rice is more of a staple ingredient than is wheat or wheat flour. In the 1980’s, it was introduced to the western part of the world, where it became a primary ingredient in many processed foods in the baking industry. Of the world’s total rice production, 90% is grown and consumed in Asia.1
White rice flour has around 7–10% protein, 75–82% carbohydrates, 0.7–1% fat.3 White rice flour milling removes the fat and micronutrient-rich bran layers. Therefore, 75–90% of vitamins B1, B6, E, and niacin are removed in this process.1 The iron level is brought down from 2.6 mg/100 g to as low as 0.4–0.6 mg/100 g.1 Iron is considered one of the most limited micronutrients in diets based mainly on polished rice. White rice flour is enriched with vitamins and minerals to meet the nutrient requirements. Rice flour is gluten-free; therefore, individuals with celiac disease can safely consume it.
It is often used as a healthier alternative to wheat flour because it is easier to digest and richer in fiber. However, because it is gluten-free, it is not able to produce the same quality and variety of products as seen in wheat flour breads and other products. It is a popular substitute for wheat flour with the addition of other flours, starches, gums, and enzymes to help mimic a gluten matrix.
Rice is first dehulled, then tempered and milled to remove its bran, then enriched. To produce more nutritious white rice flour, a process of partial boiling (parboiling) is used. The process entails soaking the rice, then heating and drying it after or before it is dehulled. During the parboiling process, thiamin migrates from the rice pericarp into the endosperm.2
Because rice posses unique nutritional, hypoallergenic, colorless, and bland taste properties, it is used in baby foods and puddings. Its role in development of foods for gluten-intolerant patients especially has been increasing. But the use of rice flour in breadmaking is still limited because rice proteins are unable to retain the gas produced during the fermentation process.
Here are several methods to enhance the quality of gluten-free products made with rice flour:
- Add transglutaminase: Rice proteins are polymerised through the transglutaminase reaction, providing a protein network necessary for holding the gas produced in fermentation. With the addition of 1% transglutaminase in the presence of 2% hydroxypropylmethylcellulose (HPMC), rice bread’s specific volume increases and its crumb becomes softer.4
- Add hydrocolloids: HPMC has been found to be the most suitable hydrocolloid, and yields rice bread with a specific volume comparable to that of wheat bread. HPMC is able to provide rice flour dough with film-forming and CO2 -entrapping properties. Other hydrocolloids like CMC and xanthan gum can’t replace HPMC by providing similar gas-retaining and film-forming properties. HPMC has been used at levels of 3.5–5.3%.5 Its usage level can be lowered by adding glucose oxidase.5
- Use modified rice flour: Bread prepared with phosphorylated rice flour showed a reduction in hardness in both 21oC and −24oC storage temperatures. Phosphorylation also shows an effect on rice bread volume and crumb appearance and color.6
Rice flour is GRAS regulated by FDA in article 21CFR170.30 of the Code of Federal Regulations.7
- Steiger, G., et al. “Fortification of rice: technologies and nutrients.” Annals of the New York Academy of Sciences, 2014, pp. 29–39, doi:10.1111/NYAS.12418.
- Delcour, J.A., and R.C. Hoseney. “Chapter 10 Rice and Oat Processing.” Principles of Cereal Science and Technology, 3rd ed., AACC International Inc., 2010, pp. 156–157.
- Verma, D.K., and P.S. Prem. “Proximate Composition, Mineral Content and Fatty Acids Analyses of Aromatic and Non-Aromatic Indian Rice.” Rice Science, vol. 24, no. 1, 2017, pp. 21–31, doi:10.1016/j.rsci.2016.05.005.
- Gujral, H.S., and M.R. Cristina. “Functionality of Rice Flour Modified with a Microbial Transglutaminase.” Journal of Cereal Science, vol. 39, no. 2, 2004, pp. 225–230, doi:10.1016/j.jcs.2003.10.004.
- Gujral, H.S., and M.R. Cristina. “Improvement of the Breadmaking Quality of Rice Flour by Glucose Oxidase.” Food Research International, vol. 37, no. 1, 2004, pp. 75–81, doi:10.1016/j.foodres.2003.08.001.
- Kringel, D.H., et al. “Influence of Phosphorylated Rice Flour on the Quality of Gluten-free Bread.” International Journal of Food Science & Technology, vol. 52, no. 5, 2017, pp. 1291–1298, doi:10.1111/ijfs.13376.
- US Food and Drug Administration. “21CFR170.30 – Code of Federal Regulations Title 21.” Accessdata.fda.gov, www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfCFR/CFRSearch.cfm?fr=170.30. Accessed 29 Aug. 2017.