New parboiling method saves water, improves nutrient content in rice
By Fred Miller
U of A System Division of Agriculture
- New parboil method saves water, improves nutrient content
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FAYETTEVILLE, Ark. — Food scientists at the Arkansas Agricultural Experiment Station have developed a new parboiling process that reduces water use up to 75 percent and improves nutrient content in rice.
Annegret Jannasch, a food science graduate student in Dale Bumpers College of Agricultural, Food and Life Sciences at the University of Arkansas, developed the new parboiling method for her graduate thesis research. She works with Ya-Jane Wang, professor of food science for the experiment station and Bumpers College.
The Arkansas Agricultural Experiment Station is the research arm of the University of Arkansas System Division of Agriculture.
Lack of nutrition
Rice is a staple food for billions of people around the world, Jannasch said. “Many people, especially in Africa and southeast Asia depend on rice for up to 70 percent of their daily calorie intake.
“But a diet of only rice can result in hidden hunger,” Jannasch said. Rice is deficient in many important micronutrients.
“Iron, calcium, folic acid and vitamin A play important roles in human health,” Jannasch said. “Iron is a key component of hemoglobin, which carries oxygen around the body in the blood. Calcium helps fight osteoporosis, high blood pressure and colon cancer.”
Jannasch added that inadequate intake of folic acid increases risks of birth defects and vitamin A deficiency can weaken the immune system.
“Where rice is the primary food, micronutrient deficiency disorders are widespread,” Wang said.
Rice can be fortified with inexpensive essential nutrients, Wang said, but current technologies — dusting the grains with a nutrient powder, adding a waxy coating of nutrients and extrusion of reconstituted grains — all have drawbacks, Wang said. Nutrients are lost during cooking and the fortification processes make the taste, color or texture of the rice less acceptable to consumers.
Jannasch investigated parboiling as a method for fortifying rice. “It’s estimated that 15 to 20 percent of the world’s milled rice is consumed as parboiled rice,” Jannasch said.
Parboiling offers higher nutrient retention rates than other methods and retains more favorable flavor and texture characteristics, Jannasch said. It’s an easy, three-step process — soaking the rice in a nutrient-enriched bath, steaming the rice and then drying it.
“But existing parboiling methods also use excess water that can present an environmental hazard if discarded without treatment,” she said. High volumes of water may also be unavailable in many arid regions.
Jannasch investigated a reduced-water parboiling process that places rice and a nutrient-enriched water bath in vacuum-sealed bags. The sealed bags are then soaked in a water bath to apply pressure that helps the nutrients migrate into the rice endosperm.
Jannasch and Wang analyzed the reduced water prepared rice for nutrient content and quality issues and compared it with fortified rice parboiled in the conventional, excess water method. They also compared nutrient and soluble solids in wastewater.
The reduced-water parboiled rice compared favorably for nutrition and quality, Jannasch said. It also reduced water use by 75 percent and wastewater volume by up to 89 percent.
“This method was efficient for fortifying parboiled rice with essential micronutrients and had minimal effects on rice quality,” Jannasch said.
Taking it to the world
Oxfam America commissioned the division to pilot test limited water parboiling process at community scale for use in Burkina Faso, an African nation with limited water resources, in 2020. Jannasch has developed a system of placing sealed vacuum bags of rice and enriched water baths in a 55-gallon drum for soaking in boiled water before steaming and drying.
An OxFam spokesperson said Jannasch and the experiment station team worked with the Oxfam team in Burkina Faso, a local research partner from the University of Ouagadougou and local women cooperatives that specialize in rice parboiling. The ongoing pilot testing seeks to evaluate utilization of this process using locally appropriate technology. The peer review for the pilot testing in Burkina Faso is forthcoming and the results are preliminary.
The method can be used for producing nutrient-fortified parboiled rice in local communities with limited water resources. Not only does the process use less water than conventional parboiling, Jannasch said, but both the nutrient baths and the water in the soaking tanks can be reused to fortify and parboil more rice, to conserve even more water.
To learn more about Division of Agriculture research, visit the Arkansas Agricultural Experiment Station website: https://aaes.uada.edu/. Follow us on Twitter at @ArkAgResearch and Instagram at @ArkAgResearch.
About the Division of Agriculture
The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land grant education system.
The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on five system campuses.
The University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services without regard to race, color, sex, gender identity, sexual orientation, national origin, religion, age, disability, marital or veteran status, genetic information, or any other legally protected status, and is an Affirmative Action/Equal Opportunity Employer.
Oxfam is a global organization that fights inequality to end poverty and injustice. We offer lifesaving support in times of crisis and advocate for economic justice, gender equality, and climate action. We demand equal rights and equal treatment so that everyone can thrive, not just survive.
The Inclusive and Resilient Food Systems team at Oxfam America seeks to promote food systems that are more nourishing, equitable, regenerative, and resilient. They believe that the way food gets from our farms to our tables can be equitable, nourishing, and sustainable, and that there can be plenty for everyone, even in the face of climate change. To achieve this, the Food Systems team works with farmers, food entrepreneurs, workers and their communities to increase their power, livelihoods and resilience; educate consumers to harness their voice to influence changes; advocate and/or partner with government and private sector actors for systemic changes; and contribute in influencing the debate on our global food system through a host of public fora and evidence generation.
Media Contact: Fred Miller
U of A System Division of Agriculture
Arkansas Agricultural Experiment Station