Blueberries are one of the most popular and nutritious fruits in the world, but they are also prone to spoilage by fungal pathogens, especially gray mold.
This causes significant economic losses and food waste for farmers and consumers alike.
However, a new study has found that a natural extract from sunflower stems could prevent blueberries from rotting and extend their shelf life.
Sunflower Stems: A Source of Antifungal Compounds
ANATOLII STEPANOV/AFP via Getty Images
Sunflowers are widely cultivated for their seeds and oil, but their flower stems, or receptacles, are usually discarded as waste.
However, researchers from the University of Chinese Academy of Sciences, Beijing, discovered that these receptacles contain chemical compounds that can fight against fungal infections in plants.
These compounds are called diterpenoids, and they have various biological activities, such as anti-inflammatory, anticancer, and antiviral effects.
The researchers extracted 17 diterpenoids from sunflower stems, including four new ones that have not been reported before.
They tested the antifungal activity of these compounds against gray mold, which is caused by the fungus Botrytis cinerea.
This fungus is one of the most common and destructive pathogens that infect fruits and vegetables, such as strawberries, grapes, tomatoes, and lettuce.
The researchers found that most of the diterpenoids showed activity against gray mold, and four of them were particularly effective at destroying the plasma membrane of the fungal cells, causing them to leak and preventing them from forming biofilms.
To test the potential application of sunflower extract in the food industry, the researchers conducted an experiment with blueberries, which are highly susceptible to gray mold after harvest.
They briefly wetted blueberries with the sunflower extract, then dried them and injected them with gray mold spores, then observed the berries for six days and compared them with untreated control berries.
The results showed that the sunflower extract protected almost half of the berries from mold growth, while all of the control berries were covered with fuzzy mold.
The researchers concluded that sunflower extract could be used as a natural biocontrol agent to prevent post-harvest disease in fruits.
They suggested that this could be a way to avoid the toxicity and resistance associated with chemical fungicides.
Moreover, they noted that sunflower extract could be a valuable source of novel diterpenoids for further research and development.
The study was published in the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society.
The authors acknowledged support from various funding sources in China.
Sunflower Oil: A Healthy Byproduct of Sunflower Stems
Besides producing antifungal compounds, sunflower stems can also be used to make sunflower oil, which is a healthy and versatile cooking oil.
Sunflower oil is extracted from the seeds of the sunflower plant, which are rich in unsaturated fats and vitamin E.
These nutrients have various benefits for human health, such as lowering cholesterol levels, boosting immunity, reducing inflammation, and protecting skin from damage.
Sunflower oil can be used for frying, baking, salad dressing, or as a substitute for butter or margarine. It has a mild flavor and a high smoke point, which means it can withstand high temperatures without burning or losing its quality.
However, not all sunflower oils are the same; some may have been processed with chemicals or heat that can reduce their nutritional value or increase their trans fat content.
Therefore, it is advisable to choose organic, cold-pressed sunflower oil that has not been refined or bleached.
