Picture delicious, warm pizza. Look closely and you’ll possibly
notice tiny pieces of leaves in the rich, red tomato sauce. You probably
never notice them, but they add an aroma and a zesty flavor, and research
is underway to improve them.
“The idea with the oregano research is to look at the composition
and the amount of oil in the leaves,” said Nurhan Dunford, an oilseed
chemist at the Oklahoma State University Food and Agricultural Products
Research and Technology Center, or FAPC.
The oregano plant has many uses for its oil or leaves, including enhancing
breads, meats, chili, salad dressings, Italian and Mexican foods, cosmetics,
pain relievers, fragrances and chewing gum. Pizza, however, is the food
item commonly associated with oregano. The herb is often paired with garlic
or other strong-flavored herbs.
“[Oregano] works well with foods that already have a fairly strong flavor, or something you’re mixing other strong flavors with, like garlic,” said Barbara Brown, food specialist at OSU. “This is why we see it in pizza sauces. The garlic and the peppers already have strong flavors. It would probably not work well with a mild flavored fish. It would be too pronounced and that’s all you’d taste.”
Most of the oregano sold in the United States is grown in Mexico.
For nearly 10 years, Ramon Silva Vazquez has studied oregano at the Federal
Research Center for Natural Resources, or CIReNA, located in Chihuahua,
Mexico. He recently completed a one-year sabbatical from CIReNA to study
at FAPC.
Silva Vazquez, the head of the oregano research program at CIReNA, began
his interest in oregano because researchers in Mexico believed wild oregano
was becoming extinct.
“That area’s soil is very poor, and the people were abusing the plants,” said Silva Vazquez. “They were cutting the plants for an extra income from the wild plant. I began the research on oregano because I wanted to save the wild plant and try to reproduce the plant.”
At CIReNA, Silva Vazquez researched ways to save the wild plant. He harvested seeds from wild plants and planted a new oregano crop. This was very difficult to do, he said.
“The first research project was trying to pretreat the seeds from the wild plant,” said Silva Vazquez. “Only 18 percent of the seeds would germinate. We used different controlled conditions to try to increase germination.”
With the pretreating method Silva Vazquez developed for the seeds, 86 percent now will germinate. It took three years to get approximately 200 acres to grow using the harvested seeds. Although the oregano plant can adapt to other areas, work continues today to adapt the plant to the desert soil in Chihuahua.
“We harvested the seeds from the wild plant to grow more,” said Silva Vazquez. “The most important thing was to start growing it. We are still working on adapting the plant to the soil in Mexico.”
The next step in the research was removing the oregano oil from the leaves. Once removed, the oil is in a crude form. Crude oregano oil contains hundreds of compounds, each emphasized to perform a certain task. The oregano must be refined through a process called hydrodistillation, which removes the undesirable components of the oil, said Dunford.
A company in the United States expressed to CIReNA an interest for oil containing higher percentages than normally found of the two most important components in oregano oil, thymol and carvacrol.
“They are looking at the bioactive compounds or compounds that contribute to the food or to their product,” said Dunford.
In Mexico, Silva Vazquez tested the effects of water stress to research changes in the percentages of these compounds. He also looked at ways the water amount affects the oil composition in the leaves.
The equipment at CIReNA was not as accurate as he needed. Silva Vazquez said he heard about FAPC from his younger brother, Jose Lorenzo Silva Vazquez, who attended OSU.
The elder Silva Vazquez contacted Dunford about researching in her laboratories at FAPC. Dunford had more accurate equipment than he had access to in Mexico, and he could better control the variables at FAPC, he said.
He came to FAPC and used the equipment, some of which Dunford designed. His year spent at FAPC and his research were funded by a group of oregano producers in Mexico.
Dunford and Silva Vazquez worked together using FAPC’s equipment to separate the components of the oil harvested from leaves in Mexico. They then tested the effects water had during the growth process on each of the components.
He learned using FAPC’s equipment allowed him to increase percentages of thymol and carvacrol naturally.
However, upon comparing the results to the plants grown in Mexico, Dunford and Silva Vazquez learned a few things were not done properly.
“Their experiments were done in the field, in the open,” said
Dunford, “so they didn’t have really good control of the amount
of water the plant gets. It all evaporates out, and they were trying to
limit the amount of water one plant gets, but if it rains what are you
going to do? That plant is going to get water.”
Dunford and Silva Vazquez started a new test and grew oregano plants at
OSU plant and soil sciences greenhouses where they could better control
the variables. They extracted the oil and compared the results with the
previous outcome.
Oregano leaves are small. They are a couple of inches in length. It takes a lot of leaves to make a small amount of oil. This, in addition to its many uses, makes the oil valuable.
“Right now the only thing we are selling is the dried leaves, but the research here is to extract the oil and the different components of the oil,” said Silva Vazquez. “All of them have different properties.”
Silva Vazquez and Dunford plan to find a way to sell the components of the oil individually. This is important because each component serves a specific need for different companies.
He said his goal in his research is to develop wild plants so that the people in the desert region of Chihuahua can produce a value-added product to make a profit.
Silva Vazquez and Dunford continue to work together long distance to look into the probabilities of other uses for oregano.
Dunford said she would like to make the technology and knowledge gained from this research available to Oklahoma products.
“We can use that technology for other plants such as cedar or other herbs,” said Dunford. “For example, we have a client interested in lemon balm oil, which is very similar to oregano oil. This year they are going to grow one acre of lemon balm plants. They are going to use the same technology to help them extract the oil from lemon balm. It’s all really interconnected.”
Although this international research does not directly involve Oklahoma at this time, working through this technology with oregano can lead to future benefits for Oklahoma agricultural products. This could create more products locally produced for the consumer in addition to revenue for the Oklahoma producer.
So next time you eat a slice of pizza, take a moment to look closely and appreciate the value of the flavor and the work and effort going into improving every bite you take.