Phytochemical Composition of the Fruits and Seed Oil of Mespilus germanica from Guba

In the quiet corners of Azerbaijan's forests, a wild tree known as the German medlar grows in dense thickets, its small, cone-shaped fruits hidden among the leaves. For centuries, local people have gathered these fruits, waiting for the first frost to soften their sharp, astringent taste before turning them into jams or traditional sauces. Beyond the kitchen, this plant has long held a place in folk medicine, used to soothe stomach troubles and support kidney health. Modern science approaches such plants with a different kind of curiosity, seeking to understand exactly what makes them work. This involves looking at the chemical building blocks inside the fruit and seeds, identifying the specific nutrients and protective compounds that give them their power. By measuring these ingredients, researchers can determine not just if a plant is useful, but how it might be best processed to keep those valuable properties intact for food or medicine.

A team of researchers from Azerbaijan set out to map the chemical landscape of the German medlar growing in the Guba district, a region known for its rich biodiversity. They wanted to move beyond general knowledge and provide a precise inventory of what is inside these wild fruits, from the sugary pulp to the hard seeds at their core. The team collected fresh fruits in late autumn, carefully separating the soft flesh from the seeds to study each part individually. Their goal was twofold: to create a detailed nutritional profile of the fruit and to test a modern method for extracting oil from the seeds without damaging the delicate compounds inside.

The analysis of the fruit pulp revealed a substance packed with energy and protective chemicals. When the water was removed from the fruit, the remaining dry mass was dominated by soluble carbohydrates, which make up about forty-one percent of the weight. These sugars provide the fruit's energy value. The pulp also contained a significant amount of fat, nearly eighteen percent, and a solid portion of protein-like substances. Perhaps most interesting was the presence of P-active compounds, a group of plant chemicals known for strengthening blood vessels and acting as antioxidants. The researchers found that the pulp was especially rich in catechins, a type of antioxidant. In the dry fruit, these compounds existed in two forms: free forms and condensed forms, with the condensed versions making up the largest group. Alongside these were chlorogenic acids and other protective molecules that help the plant survive in the wild and may offer similar benefits to humans. The fruit also proved to be a good source of minerals, particularly potassium, which is vital for heart function, as well as iron and magnesium.

Turning their attention to the seeds, the researchers explored how to get the most oil out of them while keeping it pure. The seeds are hard and difficult to process, so the team first dried and ground them into a fine powder. They then used a technique called supercritical fluid extraction, which uses carbon dioxide gas under high pressure and specific temperatures to pull the oil out of the powder. This method is preferred because it avoids the use of harsh chemical solvents that can alter the oil's quality. The team tested various conditions to find the perfect balance. They discovered that raising the temperature too high actually reduced the amount of oil they could get, likely because the heat changed how the oil dissolved in the gas. Instead, they found the best results came from keeping the temperature at a moderate forty degrees Celsius.

The pressure and time were the next variables to solve. The researchers found that running the extraction for four hours at a pressure of two hundred atmospheres yielded the maximum amount of oil without pulling out unwanted heavy waxes or paraffins that could clog the pores if used on skin. While they could extract oil faster by using a higher pressure of two hundred and eighty atmospheres, this speed came at a cost: it began to pull out those unwanted heavy fractions, lowering the quality of the final product. The oil obtained under the optimal conditions was a clear, viscous liquid with a pleasant orange color and a strong, characteristic scent. It was remarkably pure, with very low levels of free acids and almost no signs of oxidation, meaning it was fresh and stable.

When the team analyzed the fatty acids inside this oil, they found it was composed mostly of linoleic acid, which made up over seventy percent of the total, followed by oleic acid at about seventeen percent. This specific mix classifies the oil as a semi-drying oil, which means it absorbs well into the skin without leaving a greasy film. The oil was also loaded with natural antioxidants, including tocopherols, which are forms of vitamin E, and carotenoids. These components suggest the oil could be valuable for protecting the skin and fighting cellular damage. The leftover solid material from the seeds, after the oil was removed, was not waste; it still contained useful antioxidants that could be used as a food or animal feed additive.

The study concludes that the wild German medlar of the Guba region is a resource of significant nutritional and chemical value. The fruit pulp offers a rich source of sugars, minerals, and protective plant compounds, while the seeds yield a high-quality oil with a unique fatty acid profile. The researchers demonstrated that by using careful, low-temperature extraction methods, it is possible to produce a premium oil that retains its natural benefits. This work supports the idea that local wild plants can be integrated into small-scale production for functional foods and cosmetics, turning a traditional forest resource into a modern, eco-friendly product. The findings suggest that with the right processing, the full potential of these wild fruits and seeds can be unlocked for health and nutrition.