Newsletter: April 17, 2018

Researched and written weekly by the editorial team of Food Technology magazine, the IFTNEXT Newsletter explores what are, arguably, the next big things in the science of food through original reporting of scientific breakthroughs, leading-edge technology, novel food components, and transdisciplinary R&D.

HopsHops compounds may deliver a brain boost
New research suggests that a derivative of the same chemical compound found in beer has the potential to improve cognitive function in people with metabolic syndrome, a common health condition associated with cognitive dysfunction and dementia. 

The research, conducted at Oregon State University and Oregon Health & Science University, focused on a group of compounds found in hops, an essential ingredient in beer making. Researchers Fred Stevens and Jacob Raber worked with xanthohumol (XN), a prenylated flavonoid from hops, and two of its hydrogenated derivatives: DXN and TXN. 

It’s been known for some time that XN could be an effective treatment for metabolic syndrome, but there are problems associated with its use because it transforms into 8-prenylnaringenin (8-PN), which is an estrogenic metabolite. “We were always criticized about the potential side effects because 8-PN is one of the most potent phytoestrogens known in nature, and that’s not good news,” says Stevens, noting that taking XN over an extended period of time could lead to negative estrogenic side effects, such as promoting tumor growth.  

He theorized that hydrogenating the XN molecule would prevent the metabolic formation of 8-PN, thereby solving the estrogenicity problem associated with 8-PN. Test tube and cell culture tests showed that his theory was correct. Moreover, in mouse experiments, XN and its hydrogenated derivatives, DXN and TXN, improved glucose intolerance and insulin resistance and sensitivity to leptin, a hormone that helps control appetite and regulate energy expenditure—without producing adverse estrogenic effects. In fact, the derivatives were even more effective than the original compounds. 

Raber says that it’s not possible to draw definitive conclusions about the effect of these compounds in humans, but it is possible to hypothesize that they would have the power to reverse and prevent cognitive impairments. Results of the study were published in the journal Scientific Reports. 

Stevens and Raber say that they are planning for follow-up research focused on the mechanisms involved in the beneficial effects of these compounds in the brain, including those that might involve the gut-liver-brain axis. 



Raw meatReal-time analysis allows rapid detection of meat fraud
Adulteration of meat products affects meat production around the globe and is usually intended for the purpose of economic gain. Researchers in Brazil have developed a fast testing method to determine whether certain meats are authentic or adulterated. 

“Typical cases involve the substitution of high-quality meat with meat from cheaper species without its declaration on [the] label,” says Lissandra Dalsecco of Universidad Federal de Minas Gerais in Brazil and lead author of the study describing the rapid test method. “Such adulterations are not always noticeable when buying or even consuming the product, especially in the case of processed meat.” Adulterated meat products cause massive recalls and significant drops in meat sales, resulting in great financial losses. A fast, reliable test to determine adulterated meats is therefore needed. “Besides the economic losses of paying more than the product actually costs, there are health and moral issues of mislabeled meat. Mislabeled products can hide allergens and cause severe reactions [in] sensitive people,” Dalsecco adds. Adulterated meat products can also cause followers of certain faiths to unknowingly violate religious tenets about meals. “It is therefore undesirable for people with religious or lifestyle restrictions to purchase or consume meat from unwanted species,” she says. 

Dalsecco and her colleagues developed a method to accurately detect 10 different animal species, based on the principles of real-time polymerase chain reaction (PCR) analysis, which is highly specific. DNA methods to identify species rely on the assumption that members from the same species have unique DNA sequences that are different from those found in other species. “These unique sequences can be obtained from any tissue of an individual (flesh, blood, skin, etc.), amplified by PCR, and then analyzed to determine the species of origin. The high specificity and sensitivity achieved by the PCR technique allows analysis of mixtures with more than one … species and the detection of traces of a species in a product with a very high accuracy,” Dalsecco reveals. “Our method achieved 100% accuracy when applied to meat mixtures containing at least 1% of a species within the 10 target species of the study.” 

She also says that their method guarantees the quality and safety of meat products for the entire food industry, improving consumer satisfaction as well as public health. The method is described in detail in the February 2018 issue of Journal of Food Science



SalmonellaDeactivating Salmonella at lower temperatures
Researchers at Penn State University have gained insight into how Salmonella bacteria can be killed at lower temperatures, opening the door to potential improvements in food safety and savings in energy. The study, published in Biophysical Journal, details how Aida Ebrahimi, assistant professor of electrical engineering at Penn State, and her team used droplet-based impedance sensing and fluorescent imaging to demonstrate that cell death under mild heat shocks is largely due to leakage of small cytoplasmic ions. 

As device engineers, the researchers developed a sensing technology with a very small footprint, capable of measuring changes in the electrical properties of solutions containing bacteria. Ebrahimi and her team used the sensors to study the response of cells to mild heat stress. “Our hypothesis was that under mild heat stress, Salmonella dies due to weakening of intermolecular interactions between lipids that comprise cell membrane,” she says. “As a result, cytoplasmic entities (small molecules) leak out of cells upon heating. Because these small molecules are mostly ionic, we expected an increase of the electrical conductance measured using our microsensor.” 

To validate the hypothesis, the researchers performed a set of experiments using wild-type and heat-resistant Salmonella, correlating the electrical results with fluorescence measurement and standard microbiology protocols. “The heat resistant cells required higher energy to make their cell membrane permeable enough to leak small molecules,” says Ebrahimi. Using specifically engineered strains of Salmonella (GFP-producing cells), the researchers also showed that “cell lysis does not happen under mild heat shock, i.e., the observed increase of conductance is indeed due to leakage of small species rather than larger molecules such as proteins.”  

The study helps address an important gap related to the biophysics of bacterial response to mild heat stress and has potential for applications in medical diagnostics and food safety. “Specifically in food safety, there are various benefits to using lower temperatures, including energy-cost improvement and retaining better nutritional quality,” says Ebrahimi. “More importantly, bacteria can develop resistance to heat shock, so it is important to know how they respond to heat shock in order to devise better treatment strategies.” 

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Published every Tuesday, this newsletter explores what are, arguably, the next big things in the science of food.