New research into the protein quality of cultivated wild rice grown in Minnesota, sponsored by the Agricultural Utilization Research Institute (AURI), has the potential to open up new markets and new uses for one of Minnesota’s most iconic crops.
AURI partnered with researchers at the University of Minnesota’s Department of Food Science and Nutrition, the Minnesota Department of Agriculture and the Minnesota Cultivated Wild Rice Council on the project.
Researchers set out to answer three key questions to provide data on the nutritional characteristics of wild rice, its effect on the microbiome and help explain why the product hardens when cooked with sweeteners. Participants say the data gathered is useful for wild rice farmers and marketers who wish to capitalize on the popularity of plant protein-based diets and show that wild rice has health benefits for consumers suffering from a variety of health issues.
There were three main objectives. The first was to determine the protein quality of cultivated wild rice, compared to brown rice, using the protein digestibility-corrected amino acid score (PDCAAS) method. The second was to determine the large intestinal microbial profile, or the gut microbiome of a cultivated wild rice diet compared to a brown rice diet. The third was to investigate why wild rice hardens when cooked with a sweetener like sugar.
The study consisted of feeding rats. One group received cultivated wild rice and a control group received brown rice. At the end of the first stage of the trial, researchers switched diets of each group.
Researchers then collected the rats’ feces and tested for nitrogen levels to determine protein absorption rates in each group. Determining how well the rats could absorb the protein provides researchers with a PDCAAS score. The PDCAAS score is recognized by the U.S. Food and Drug Administration and required in order to make a protein claim on food products.
The results of the study were positive, said Dan Gallagher, a professor of nutrition at the University of Minnesota.
Both wild rice and brown rice had good PDCAAS scores for plant protein sources and had better protein nutritional qualities when compared to other common grains like wheat and barley. Brown and wild rice also had higher PDCAAS scores when compared to common legumes.
The protein quality of cultivated wild rice is very strong, however, the PDCASS score was impacted due to a lower level of the amino acid lysine. Overall, cultivated wild rice and brown rice have equivalent protein qualities.
There is potential to increase the PDCAAS score of cultivated wild rice using alternative cooking methods. Further, when combined in a food product with other common protein sources like peas and lentils, the overall PDCAAS score of a food product would meet the FDA standards of a good source of protein.
Further, the study showed that in a high fat diet, wild rice greatly reduced cholesterol and total fat in the liver of rats. Liver fat is an early indicator of non-alcoholic fatty liver disease, a serious and growing health issue.
Researchers also concluded that a wild rice diet changed the bacteria profile of the rats and has a positive influence on the microbiome.
There were two observations related to the hardening of wild rice when cooked. First, moisture loss is a main driver for the hardening of wild rice. However, new packaging and cooking methods of cultivated wild rice could help reduce the moisture loss and the hardening of the rice in sucrose.
The research is important and presents many opportunities and further avenues of study.
Peter Imle is a cultivated wild rice farmer in northwest Minnesota. He said it is time for the wild rice industry to update its nutritional data as consumers’ trends now favor diets with more plant proteins and whole grains.
“Part of the story we hope to tell about wild rice is that it is a healthy protein alternative when compared to other products, but in order to do that, we needed data to support that claim. Now that we have that PDCAAS score it is going to help the industry going forward. It is important for producers and marketers to have this information to inform consumers. This is a great start,” Imle said.
Cultivated wild rice is a significant industry in Minnesota. Wild rice is the state grain, and it is the only cereal grain native to North America. Minnesota is the world’s largest producer of wild rice.
The Red Lake Nation, for example, operates the fifth largest cultivated wild rice farm in the state,” said Beth Nelson, president of the Minnesota Cultivated Wild Rice Council.
“From an economic standpoint, wild rice generates $58.4 million for the state’s economy and 641 jobs annually. Growing wild rice also brings much needed income to some of the poorest counties in Minnesota.
Wild rice production is environmentally sustainable, and the grain is GMO free, gluten free and rich in antioxidants. It is also an excellent source of a healthy diet. In addition to being high in protein, a single serving provides more than half of the daily recommended whole grains, all nine of the essential amino acids and is low in calories. It also serves as an extender in ground beef to reduce fat and cholesterol, improve taste and lengthen frozen storage life. “It really is a super food,” Nelson said.
Wild rice is also capital and labor intensive to grow, and the amount of farmable land is finite, said Imle. Cultivated wild rice is grown by a small network of producers when compared to large commodities like corn and soybeans.
Grower groups often allocate funding for production or marketing research which is why collaborative studies like this one with AURI are so important to the industry, Imle said. The council focuses on research that improves productivity and the consumer experience with cultivated wild rice.
“That is where our focus has been from the beginning and where the majority of our check off dollars go,” said Imle.
“A project like this with a rat feeding study is very expensive. We are fortunate to have something like AURI in our state. AURI does a great job of filling a niche when a group like ours wants to try something that is a little outside the mainstream. Having an organization to partner with like AURI and its resources means we can investigate some of these issues.”
In addition to the protein quantity data, the study also shows cultivated wild rice has the potential to help in a growing health concern, said Gallagher.
“Non-alcoholic fatty liver disease is fairly common in people that are overweight and in people with diabetes. It is a very serious health concern and there is no drug treatment available currently. It is important to try to find a dietary approach that can help combat this issue, especially in high fat diets. If cultivated wild rice can be one of the solutions, that is something we want to pursue,” he said.
Gallagher said additional research into the large intestinal bacteria from a wild rice diet is especially exciting. This research was able to prove a wild rice diet changes the bacteria profile, but more research is needed to identify how much the profile changed and what kinds of new bacteria a wild rice diet produces.
“That is significant. Past studies have demonstrated associations with particular bacteria profiles and various health conditions. Issues like colon cancer and even mental depression can be related to the bacteria profile in an individual’s large intestine,” Gallaher said.
Nelson said the study originated after the council received an inquiry from a food producer asking for wild rice’s protein score. The company was exploring using wild rice as an ingredient in cereal bars. The council worked with its producers to refine the request into a formal research project and then contacted AURI to find funding to supplement the council’s check off dollars. Ultimately, the council applied for a grant through AURI’s Ag Innovation Partnership project. AURI’s Lolly Occhino, senior food scientist, and Michael Sparby, commercialization director, worked with the council and the University of Minnesota on this project. Additional dollars came from the Minnesota Department of Agriculture.
“This project just shows that we can accomplish so much more when we can collaborate and work together than we can independently,” said Nelson, president of the Cultivated Wild Rice Council. “AURI and all the partners were excellent to work with on this project.”
AURI has a long-standing relationship with the Cultivated Wild Rice Council and was eager to continue that work with this important research.
“Wild rice plays a significant role in Minnesota’s agricultural community, its past, present and its future. It is a very important crop in our state and adds value to the economy. Any time we can spotlight the industry, assist the producers and potentially find new uses for wild rice, it is a great opportunity for AURI to contribute,” said Occhino.