The Smell of Dark Chocolate, Demystified

Chocolate is one of the most-consumed treats around the world, and the smell alone is usually enough to evoke strong cravings from even the most disciplined eaters. Much like a fine wine, high-quality dark chocolate has a multi-layered scent and flavor, with notes of vanilla, banana or vinegar. Now, researchers report in ACS’ Journal of Agricultural and Food Chemistry which substances — and how much of them — make up this heavenly aroma.

Flavor is more than just what the tongue tastes — smell also plays a key role, with many compounds working together to create a unique sensory experience. Although nearly 600 compounds have been identified in chocolate over the last century, only a fraction of them are known to contribute to the aroma. Previous studies have identified compounds responsible for the scent of milk and dark chocolates, but it’s been unclear how much of each component is needed to make something smell specifically like dark chocolate. To uncover this olfactory mystery, Carolin Seyfried and Michael Granvogl decided to build the scent from scratch for the first time using state-of-the-art methods.

The researchers purchased two types of dark chocolate, each with a distinguishable aroma, from a local grocery store. With aroma extract dilution analysis, they identified the volatile compounds that likely contributed to the bars’ scents. Next, they measured the amounts of the compounds with stable isotope dilution analysis. Some of these substances, such as the violet-scented β-ionone, were quantified for the first time in chocolate. Finally, using these data, the team reconstructed the aromas of the two dark chocolates, which smelled very similar to the original bars, according to a trained sensory panel. The researchers say this finding shows that the essential aroma compounds in chocolate were correctly identified and quantitated.

The findings were pblished in the Journal of Agricultural and Food Chemistry.

Source: American Chemical Society

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Study: Smelling Dysfunction Found Associated with Impaired Cognition

In a large population-based study of randomly selected participants in Germany, researchers found that participants aged 65-74 years with olfactory dysfunction showed impaired cognitive performance. Interestingly, this strong association was not present in younger (55-64 years) or older (75-86 years) participants. Additionally, the effect was more present in women than men.

In neurodegenerative diseases like Parkinson’s and Alzheimer’s disease (AD), olfactory function is diminished. Further, olfactory dysfunction precedes the onset of cognitive impairment within AD, which highlights its potential as biomarker for early, preclinical diagnosis. Several studies suggest that olfactory dysfunction predicts progression from normal cognitive functioning to mild cognitive impairment and AD. There is little evidence for this association concerning different age stages and gender differences.

The Heinz Nixdorf Recall (Risk Factors, Evaluation of Coronary Calcium and Lifestyle) study is an observational, population-based, prospective study that examined 4,814 participants (baseline: 45-75 years; 50% men) in the metropolitan Ruhr Area. Participants returned for two examinations every five years. For this analysis, 2,640 participants from the third examination were divided into anosmics (lack of olfactory function), hyposmics (impaired olfactory function) and normosmics (normal olfactory function) according to their Sniffin’ Sticks Screening test scores. To examine age- and gender-specific associations, stratified analyses for gender and three age groups were conducted. Men and women differed significantly in their olfactory function. Women had higher scores on the olfactory test. Particularly, middle-aged anosmic male and female participants showed worst performance in several cognitive tests. No associations were seen in younger and older adults. There was a quantitative association in all age groups as anosmics performed worse than hyposmics and hyposmics performed worse than normosmics in all subtests.

The found association in the middle-aged group might occur because this age band between 65-74 years is critical for the onset of age-related cognitive and olfactory decline. Regarding the older age group, the association may be covered by other risk factors occurring in this age band like hypertension, diabetes or coronary artery disease. The pathology potentially causing olfactory and cognitive impairment mainly occurs after the age of 65. Thus, the young-aged groups are cognitively healthier and are less often anosmics. This might account for the missing associations in this age group. Nevertheless, cognitive performance was reflected by the decrement in olfactory function in all age groups. Participants with worst olfactory function showed worst cognitive performance and vice versa. More distinct effects were found for women compared to men. General differences in olfactory function between men and women can be the cause of this result. At this point we cannot conclude clinical implications regarding gender.

This is the first study reporting on age-specific associations of olfactory function and cognitive performance in the general population. Testing olfactory function is an easy and inexpensive way to detect dysfunctions and can help to identify individuals at risk of cognitive decline. Assessing olfactory function may be an appropriate marker to detect persons at risk of cognitive decline, especially in a crucial age stage between 65 and 74 years.

Source: EurekAlert!

Why Wagyu Beef Smell So Good?

For about $150 per pound, dedicated carnivores and food connoisseurs alike can get their forks on a luxury: Wagyu beef. Its trademark marbled flesh and soft texture have launched the meat into caviar-like status. And because its fat has a melting point lower than the average human body temperature, it melts in your mouth. The vast majority of the beef comes from Japanese Black cattle.

Part of its allure is the smell — a unique sweet, coconut-like aroma. New research from the Journal of Agricultural and Food Chemistry pinpoints 16 compounds that give it this distinct smell, 10 of which are newly associated with the meat. The strongest element: compounds derived from fatty acid.

Satsuki Inagaki, the lead author, says that while the smell of the beef is important, scientists weren’t sure what was behind it. The paper points out that a previous study identified one compound that that played a large role in the beef’s smell, but that there was a potential flaw in the study: the meat wasn’t cooked to an optimal temperature.

In the recent research, conducted through Ogawa & Company, Ltd., the researchers analyzed several beef samples — along with Wagyu they looked at grass-fed Australian beef and U.S. beef as comparisons.

Alone, these compounds are not necessarily special. Inagaki says that some are also found in foods like tea, beer, citrus fruits, fennel and peanuts. The paper explains that one compound is associated with egg whites, and another with cooked chicken. What sets Wagyu beef apart from other foods, Inagaki explains, is the balance of these compounds.

The largest contributor to the Wagyu smell is a compound derived from fatty acid. There’s some logic to this — there’s a lot of fat in Wagyu beef. Looking at the flesh, or a photo of it at least, you can see flecks of fat in the meat. Stephen Smith, Texas A&M professor of meat science says, “To me, it’s a sea of white with a few flecks of red.” Smith explains that the cattle are bred and raised to have 30 to 40 percent fat in the muscle. He says that typical U.S. beef won’t even come close to that.

Iowa State University professor of animal science Joseph Sebranek explains, “It’s a genetic trait of these particular breeds of cattle to lay down more fat and give a different fatty acid composition.”

Smith adds that it’s also partially dietary — the animals are typically fed corn and are kept alive longer than other types of cattle. High quality U.S. beef is from animals likely fed for 16 to 18 months, he says, while Wagyu beef is fed for at least 30 months.

If you’re trying to sink your teeth into this beef in the U.S., good luck. Wagyu, Smith says, means “Japanese style cattle,” and hails from four Japanese breeds. There is “American Wagyu” from exported Japanese cattle, but it’s difficult to say just how purely Wagyu it is.

You also might see it referred to as “Kobe beef” in the U.S., which is actually a specific type of Wagyu beef produced only in a particular area of Japan. It’s unlikely you’ll find it in the U.S. — there are only about 3,000 cattle each year that are certifiable Kobe beef, and until 2012, it wasn’t shipped outside of Japan.

Why do you see restaurants advertising Kobe burgers then? Forbes.com writer Larry Olmstead wrote a popular series on Kobe beef. He explained on All Things Considered that under U.S. law, there aren’t any specific rules as to what qualifies as Kobe beef, “so we can call pretty much anything we want Kobe.”

To catch a whiff of this aromatic beef and a taste of its fatty acid, your best bet is probably to go to Japan.

Source: npr

Scientists Discover Anatomical Link for the Loss of Smell in Parkinson’s Disease

The first symptom of Parkinson’s disease is often an impaired sense of smell. This neurodegenerative disease primarily causes irreparable damage to nerve cells in a brain area involved in movement control. How it affects the olfactory system has been unclear. Researchers at the Max Planck Research Unit for Neurogenetics in Frankfurt and the University of Auckland in New Zealand have now carried out a study comparing the olfactory bulbs of individuals with and without Parkinson’s disease. The researchers found that the total volume occupied by the functional units in the olfactory bulb – the so-called glomeruli – is in Parkinson’s cases only half that in normal individuals. Moreover, the distribution of the glomeruli within the olfactory bulb is altered in Parkinson’s cases.

Nine out of ten patients with Parkinson’s disease suffer from defects of the sense of smell in the early stages of the disease – often years before the appearance of the motor symptoms that are characteristic of the disease. The motor symptoms are caused by a loss of nerve cells in the region of the substantia nigra in the brain that is responsible for controlling movement. What causes this cell death has not yet been fully clarified, but a key role appears to be played by Lewy bodies. These are inclusions, inside the cells, that contain a misfolded, defective version of the alpha-synuclein protein. Lewy bodies are found in the olfactory bulb before they appear in the substantia nigra.

The so-called olfactory vector hypothesis for Parkinson’s disease proposes that environmental factors, such as viruses, heavy metals or pesticides, are risk factors or even causes of the condition. No other sensory system than the olfactory system is in such close contact with the external environment – the inhaled air. The hypothesis posits that the disease-causing agent is introduced from the nasal cavity into the olfactory bulb, where Parkinson’s disease is triggered and gradually spreads through other parts of the brain.

Source: MAX-PLANCK-GESELLSCHAFT

Failing Sense of Smell Tied to Dementia Risk

Older adults who’ve lost their sense of smell appear to have an increased risk of dementia, a new study suggests.

The long-term study included nearly 3,000 participants, aged 57 to 85, who were tested on their ability to identify five common odors.

At least four of the five odors were correctly identified by 78 percent of the participants, the researchers found. In addition, 14 percent identified three of the odors, 5 percent identified only two of the odors, 2 percent identified only one, and 1 percent could not identify any of the odors.

Five years after the test, the participants who weren’t able to identify at least four of the five odors were more than twice as likely to have dementia, compared to those with a normal sense of smell, the researchers said.

Nearly all of the participants who couldn’t identify a single odor had been diagnosed with dementia, along with 80 percent of those who identified only one or two of the five odors, according to the report.

“These results show that the sense of smell is closely connected with brain function and health,” study lead author Dr. Jayant Pinto, an ENT (ear, nose and throat) specialist at the University of Chicago, said in a university news release.

“We think a decline in the ability to smell, specifically, but also sensory function more broadly, may be an important early sign, marking people at greater risk for dementia,” Pinto explained.

“We need to understand the underlying mechanisms, so we can understand neurodegenerative disease and, hopefully, develop new treatments and preventative interventions,” Pinto said.

The study’s co-author, Martha McClintock, an expert in olfactory (sense of smell) and pheromonal (chemical secretion) communication, noted that the olfactory system also has stem cells that self-regenerate.

So, McClintock explained, “a decrease in the ability to smell may signal a decrease in the brain’s ability to rebuild key components that are declining with age, leading to the pathological changes of many different dementias.” McClintock is a professor of psychology at the University of Chicago.

Although the researchers found an association between an inability to identify odors and development of dementia, they couldn’t prove a cause-and-effect relationship.

The study was published Sept. 29 in the Journal of the American Geriatrics Society.

In an accompanying journal editorial, Dr. Stephen Thielke, from the Puget Sound Veterans Affairs Medical Center in Washington, added a cautionary note.

Loss of the sense of smell may be easier to measure over time than loss of mental function, which could allow for earlier assessment of brain changes, he said. “But none of this supports that smell testing would be a useful tool for predicting the onset of dementia,” Thielke said in the news release.

Source: HealthDay


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