Waste from Making Purple Corn Chips Yields a Natural Dye, Supplements, Kitty Litter

From the ACS Press Room Waste from Making Purple Corn Chips Yields a Natural Dye, Supplements, Kitty Litter

“Biorefinery Approach Applied to the Valorization of Purple Corn Cobs” ACS Sustainable Chemistry & Engineering

.The more colorful a food, the more nutritious it probably is. For example, purple corn contains compounds associated with a reduced risk of developing diabetes and heart disease. The cobs contain the same compounds but are typically thrown out. Now, researchers report a step-wise biorefinery approach in ACS Sustainable Chemistry & Engineering that uses the whole cob, producing a dye and a possible nutraceutical with the pigments, and an animal litter with the leftovers. Eating a rainbow of fruits and vegetables provides a variety of health benefits, with vitamins and nutrients stored within the plant’s colorproducing compounds. One group of compounds contributing distinct hues to food are anthocyanins — vibrant pigments desired as natural dyes that also have antioxidant and anti-inflammatory properties. Anthocyanins are found in purple corn’s kernels and the corncobs, which are

Researchers extracted pigment from purple corn cobs (right) for supplements and dyeing fabrics (top left), and tested the remaining grounds (bottom left) for animal litter.

typically discarded. Past attempts at repurposing cobs have involved harmful and expensive solvents to extract compounds. Water could be used as an eco-friendly and costeffective agent for this process, but it is not very efficient. And then the insoluble cob material is still left over as waste. So, Fabrizio Adani, Roberto Pilu, Patrizia De Nisi and colleagues wanted to extract beneficial pigments from purple corncobs with a multistep approach to make many value-added products, while also closing the loop with zero waste at the end. The researchers devised a biorefinery approach to extract anthocyanins from a new variety of purple corn they developed. First, ground-up corncobs and water were mixed and heated, removing 36% of the pigments compared to methods with acetone and ethanol solvents. The pigments from this step were used to dye cotton and wool fabrics. In the next step of the biorefinery method, the researchers removed an additional 33% of the anthocyanin content from the watertreated cobs with an ethanol mixture. These extracts showed antioxidant activity and antiinflammatory properties in cells in petri dishes and could be used in the future to develop nutraceutical supplements, the researchers say. Finally, the team found that the remaining insoluble purple grounds were similar to commercial corncob animal litter. In tests, the residual cob material was even more ab-

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From the ACS Press Room Cracking Open the Mystery of How Many Bubbles are in a Glass of Beer

“How Many CO2 Bubbles in a Glass of Beer?” ACS Omega

After pouring beer into a glass, streams of little bubbles appear and start to rise, forming a foamy head. As the bubbles burst, the released carbon dioxide gas imparts the beverage’s desirable tang. But just how many bubbles are in that drink? By examining various factors, researchers reporting in ACS Omega estimate between 200,000 and nearly 2 million of these tiny spheres can form in a gently poured lager. Worldwide, beer is one of the most popular alcoholic beverages. Lightly flavored lagers, which are especially well-liked, are produced through a cool fermentation process, converting the sugars in malted grains to alcohol and carbon dioxide. During commercial packaging, more carbonation can be added to get a desired level of fizziness. That’s why bottles and cans of beer hiss when opened and release micrometer-wide bubbles when poured into a mug. These bubbles are important sensory elements of beer tasting, similar to sparkling wines, because they transport flavor and scent compounds. The carbonation also can tickle the drinker’s nose. Gérard Liger-Belair had previously determined that about 1 million bubbles form in a flute of champagne, but scientists don’t know the number created and released by beer before it’s flat. So, Liger-Belair and Clara Cilindre wanted to find out. The researchers first measured the amount of carbon dioxide dissolved in a commercial lager just after pouring it into a tilted glass, such as a server would do to reduce its surface foam. Next, using this value and a standard tasting temperature of 42 F, they calculated that dissolved gas would spontaneously aggregate to form streams of bubbles wherever crevices and cavities in the glass were more than 1.4 µmwide. Then, high-speed photographs showed that the bubbles grew in volume as they floated to the surface, capturing and transporting additional dissolved gas to the air above the drink. As the remaining gas concentration decreased, the bubbling would eventually cease. The researchers estimated there could be between 200,000 and 2 million bubbles released before a half-pint of lager would go flat. Surprisingly, defects in a glass will influence beer and champagne differently, with more bubbles forming in beer compared with champagne when larger imperfections are present, the researchers say. The authors acknowledge funding from the French National Centre for Scientific Research (CNRS).