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Why ripe strawberries smell so distinctive 

Scientists from the Technische Universitat Munchen (TUM) have identified the compound that gives ripe strawberries their characteristic caramel-like aroma. 

According to the scientists, the smell of a fresh strawberry is the result of around a dozen different aroma compounds and one of these plays a particularly important role: HDMF (4-hydroxy-2,5-dimethyl-3(2H)-furanone), which is also known under the brand name Furaneol.  “A ripe strawberry has a particularly high concentration of this compound – up to 50 milligrams per kilo – which lies a far above the odor threshold. This compound gives the ripe fruit its characteristic caramel-like aroma,” Prof. Wilfried Schwab, head of Biotechnology of Natural Products at TUM, who has spent many years researching the biological structure of this substance, explained. 

HDMF is also found in pineapples and tomatoes. In plants, the aroma develops in a multi-step pathway from the from the fruit sugar fructose. 

“We were particularly interested in the biocatalytic process that leads up to the final compound,” said Prof. Arne Skerra from the TUM Chair of Biological Chemistry.

In this process, a molecule precursor binds to the FaEO enzyme (Fragaria x ananassa enone oxidoreductase), which converts it into the final product, namely HDMF. 

The TUM scientists were able to map this reaction path in detail. To understand how enzymes catalyze the biosynthesis of these new metabolic products, the research team took advantage of X-ray structural analysis. This allowed them to view the 3D structure of the molecules.
Living close to major road may damage kidney function

Scientists have found that people, who live closer to a major road, may have their kidney function impaired. 

The scientists based their findings on more than 1100 adults who had sustained a stroke between 1999 and 2004 and had been admitted to hospital in the greater Boston area of Massachusetts in the US. 

On admission, each patient’s serum creatinine was measured. This is a by-product of muscle metabolism and is filtered out of the body by the kidney, known as the glomerular filtration rate or GFR. The GFR is therefore an indicator of the health of the kidneys and how well they are working. 50 percent patients lived within 1 km of a major road, with the rest living between 1 and 10 km away. After taking account of influential factors, like age, sex, race, smoking, underlying conditions, treatment for heart conditions, and neighbourhood affluence, patients who lived closest to a major road had the lowest GFR.
Salt levels in fast food still ‘dangerously’ high

Despite calls from public and health agencies for the food industry to voluntarily reduce sodium levels, a study has found that the processed food and fast food still have dangerously high salt levels. The new Northwestern Medicine study conducted with the Center for Science in the Public Interest, assessed that the sodium content in selected processed foods and in fast-food restaurants in 2005, 2008 and 20011. 

The study found that between 2005 and 2011, the sodium content in 402 processed foods went down by about 3.5 percent, while the sodium content in 78 fast-food restaurant products went up by 2.6 percent. 

Although some products showed decreases of at least 30 percent, a greater number of products showed increases of at least 30 percent. 

Stephen Havas, M.D., corresponding author of the paper and a research professor of preventive medicine at Northwestern University Feinberg School of Medicine, said that the voluntary approach has failed. 

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