Every great bottle of wine begins with a humble fungal infection. Historically, winemakers relied on naturally occurring yeasts to convert grape sugars into alcohol; modern vintners typically buy one of just a few laboratory-grown strains. Now, to set their products apart, some of the best winemakers are revisiting nature’s lesser-used microbial engineers. Not all these strains can withstand industrial production processes and retain their efficacy—but a natural additive offers a possible solution, new research suggests.
Industrial growers produce yeast in the presence of oxygen, which can damage cell walls and other important proteins during a process called oxidation. This can make it harder for yeasts—which are dehydrated for shipping—to perform when winemakers revive them. Biochemist Emilia Matallana of the University of Valencia in Spain and her colleagues have been exploring practical ways to fend off such oxidation for years. After showing that pure antioxidants worked, they began searching for a more affordable natural source. They found it in argan, an olivelike fruit used for food and cosmetics. The trees it grows on are famously frequented by domesticated goats.
Matallana and her team treated three varieties of wine yeast (Saccharomyces cerevisiae) with argan oil, dehydrated them and later rehydrated them. The oil protected important proteins in the yeasts from oxidation and boosted wine fermentation, the researchers reported in a study published online in June in Innovative Food Science & Emerging Technologies.
Microbiologists are now interested in studying how and why each yeast strain responded to the argan oil as it did, says enologist Ramón González of the Institute of Grapevine and Wine Sciences in Logroño, Spain, who was not involved in the work. The oil may one day enable vintners to use a wider range of specialized yeasts, putting more varied wines on the menu. As for how the oil affected the wine’s taste, Matallana says it was “nothing weird.”
This story first appeared in the September 2018 issue of Scientific American: [html] [pdf].
Mexico kicked off 2017 with a 20 percent spike in gasoline prices, driven in part by the phasing out of subsidies. Some consumers set fires at gas stations—a response that highlights the backlash countries can face as they stop subsidizing carbon-based fuels and start encouraging climate-friendly alternatives. Now the Mexican government and stock market are experimenting with a gentler tool for discouraging carbon emissions: cap-and-trade. Mexico, which in 2012 passed the developing world’s first climate law, is well placed to set an example for other developing economies looking to shrink their carbon footprints.
For several days in late September 2015, heavy rains soaked the earth surrounding the district of El Cambray II in Guatemala. On the first night of the following month, steep slopes, long held in place by thick, tropical tree roots, suddenly gave way, burying hundreds of homes in mud up to 15 meters deep. At least 280 people died.
Officials had warned residents for years that the area was at risk, but a mixture of poverty and mistrust leads some of the poorest people in Central America and beyond to build and live on marginal land. Still, residents of El Cambray II might have been willing to temporarily evacuate, if they had received a credible and precise warning. And if such warnings were available worldwide, they could help reduce the 3,000 deaths attributed to landslides every year. Continue reading