25-Jul-2017 - University of Illinois at Urbana-Champaign

Name that Scotch

Colorimetric recognition of aldehydes and ketones

Vodka tastes different from brandy, and connoisseurs can distinguish among different brands of whiskeys. The flavors of spirits result from a complex bouquet of volatile compounds. New colorimetric sensor arrays on disposable test-strips read by hand-held devices allow for their rapid, inexpensive, and sensitive identification by their chemical “fingerprints”. They are based on novel sensor arrays that detect and differentiate among a diverse range of aldehydes and ketones.

Many volatile compounds can now be detected quite well by “electronic noses” that were inspired by the olfactory receptors of animals and provide characteristic chemical fingerprints for scents and mixtures of scents. Because the binding of scent molecules must be reversible for the nose to be reusable, only weakly binding chemical receptors can be used, which limits sensitivity and selectivity. As an alternative, a team working with Kenneth S. Suslick has developed inexpensive, colorimetric, disposable test strips based on strong interactions between the sensors and the analyte molecules. Unlike electronic noses, a variety of chemically reactive dyes are arranged into a sensor array and are simply printed like “chemical ink”. Different analyte molecules bind to the individual reagent areas with different degrees of strength, causing the reagents to change color. The result is a characteristic pattern of color changes that can be detected and analyzed by common pattern recognition techniques with a hand-held device.

Inspired by classic spot tests used to indicate the presence of aldehydes and ketones through color changes in aniline and phenylhydrazine dyes, the researchers from the University of Illinois at Urbana-Champaign (USA) expanded the repertoire of their colorimetric sensor arrays. The new array was able to detect and differentiate numerous different aldehydes and ketones at concentrations below 0.0001 %.

This type of sensitive, fast, and inexpensive method for detecting volatile aldehydes and ketones is of use in many fields: from the detection of chemical toxins like formaldehyde, to safety and food inspections, and preventative screening. For example, detection of acetone and acetoacetate could indicate dangerous ketosis in diabetics. Substances like vanillin, diacetyl, and furfural, which are produced in the fermentation and ageing of beers and spirits, contribute significantly to their flavors.

To highlight potential applications for quality control in the food and beverage industries, the researchers developed a sensor array for spirits. It includes indicators for aldehydes and ketones as well as a number of other classes of substance such as carboxylic acids, sulfides, amines, and polyphenols, registering a broader palette of the aromatic compounds that make up the specific flavors of spirits. For the sophisticated consumer, this complex mixture, the bouquet, has to be just right to guarantee the quality of the beverage. It was possible to unequivocally distinguish whiskies from brandy or vodka and even among different brands of whiskeys, bourbons, and scotches.

University of Illinois at Urbana-Champaign

Request information now

Recommend news PDF version / Print

Share on

Facts, background information, dossiers
  • whisky
  • ketones
  • aldehydes
More about UIUC
  • News

    Growth factors in single cells counted for the first time

    Whether healthy or diseased, human cells exhibit behaviors and processes that are largely dictated by growth factor molecules, which bind to receptors on the cells. For example, growth factors tell the cells to divide, move, and when to die--a process known as apoptosis. When growth factor ... more

    Novel quantum dots enhance cell imaging

    A team of researchers from the University of Illinois at Urbana-Champaign and Mayo Clinic have engineered a new type of molecular probe that can measure and count RNA in cells and tissue without organic dyes. The probe is based on the conventional fluorescence in situ hybridization (FISH) t ... more

    New informatics tool makes the most of genomic data

    The rise of genomics, the shift from considering genes singly to collectively, is adding a new dimension to medical care; biomedical researchers hope to use the information contained in human genomes to make better predictions about individual health, including responses to therapeutic drug ... more

More about Angewandte Chemie
  • News

    A molecular shield for near-infrared fluorescent dyes

    Scientists can monitor biomolecular processes in live tissue by noninvasive optical methods, such as fluorescence imaging. However, the fluorescent dyes used for that purpose are often rather unstable, and photobleaching, lack of specificity, and poor pharmacokinetics are recurrent issues. ... more

    Staining Cycles with Black Holes

    In the treatment of tumors, microenvironment plays an important role. It often contains immune cells that are so changed that they promote tumor growth. In the journal Angewandte Chemie, scientists have introduced a method by which cell samples from tumors and their surroundings can rapidly ... more

    Amplification and imaging of microRNA as a biomarker to detect tumor development

    A good indicator of dysregulation in live cells is a change in their RNA expression. MicroRNA (miRNA), a special type of RNA, is considered a biomarker for carcinogenic cells. A team of scientists from China has found a way to amplify miRNA in live tumor cells for bioimaging. As they report ... more