BEIJING, Nov. 20 (Xinhua) -- Blueberries are tart, juicy but do not last very long once they have been picked, so it is best to eat them quickly before they turn into mush. All this could change, however, as a new study found that compounds from sunflower crop waste could prevent rotting in the gem-like fruit, helping prolong its shelf life.

Led by researchers from Kunming Institute of Botany under the Chinese Academy of Sciences, the study focused on sunflower stems, which are generally considered to be a waste product.

Previous experiments show the stems are resistant to many plant diseases, so researchers decided to explore whether the stems might have components responsible for this protective effect, and whether they could be used to fight fungal plant pathogens in fruit, as a way to avoid the toxicity and resistance associated with chemical fungicides.

The researchers used chemicals to prepare extracts from sunflower stems. They then isolated and identified the components in these extracts. They found 17 diterpenoids, most of which showed activity against gray mold. Four of the compounds -- including two of the newly identified ones -- were effective at destroying the plasma membrane of this fungus, causing its cells to leak and preventing it from forming biofilms.

In another test, the researchers wet blueberries with the stem extracts, then dried the fruits and injected them with mold. Over a period of six days, the extracts protected almost half the berries from mold growth.

The study results were published in the Journal of Agricultural and Food Chemistry, a publication of the American Chemical Society. The researchers suggest that the food industry could use the natural antifungal compounds to protect against post-harvest diseases.