Many love a combination of milk and coffee, creating the rich, creamy taste that makes your morning brew so special. This may sound like a simple combination, but researchers have in recent years got to the bottom of what exactly happens at the molecular level when milk and espresso collide. Using advanced infrared spectroscopy, a study published by the American Chemical Society (ACS) dived down to the microscopic dynamics of milk proteins in interaction with caffeine.  Even in that aromatic whirl of an espresso, surprisingly the proteins in milk remain resilient, at least enough to maintain their structure and mouthfeel. This discovery opens doors to new ways of understanding coffee’s complex chemistry—and here’s how.

The Milk-Coffee Interaction

Tobias Weidner and Fani Madzharova, the lead researchers for this study, studied how milk proteins and caffeine react in water and a coffee beverage. They recorded molecular snapshots using infrared spectroscopy, which shows that milk proteins retain their structural integrity. Even in a handmade cappuccino brimming with coffee-extracted compounds like chlorogenic acid, this resilience of milk proteins to preserve texture and taste was observed. However, this finding contradicts past suppositions that milk proteins could be subject to large changes in texture or digestibility with the contact of the active components of coffee.

How Infrared Spectroscopy Worked in the Study

Using 2D infrared spectroscopy, a powerful technique that reveals details about the vibrations and structures within molecules, the researchers looked at mixtures of milk, water, and caffeine. Through this method, they were able to see how milk proteins respond to caffeine on the molecular level. By seeing how these proteins behaved in different mixtures—from water solutions to a cappuccino—for example where the presence of caffeine did not change the shape or the dynamics of the proteins, they confirmed that these proteins did not radically alter behavior in response to the presence of an unwanted contaminant. With implications not only for coffee enthusiasts but also for food scientists exploring new milk and coffee beverages with desired texture and taste, this revelation.

Madzharova and Weidner (2024) investigated the correlation between center line slopes (CLS) for different chemical environments. They reported the CLS of the caffeine cross peak at (1695, 1645) cm⁻¹ in pure caffeine, milk with caffeine, and milk with caffeine minus milk difference spectra (red squares, blue circles, and black triangles, respectively) as a function of waiting time between the pump and probe pulses. Similarly, the CLS of the diagonal milk fat peak at (1745, 1745) cm⁻¹ was analyzed for pure milk, the milk-caffeine mixture, and milk with caffeine minus caffeine difference spectra (green squares, blue circles, and pink triangles, respectively), highlighting distinctions in molecular interactions and spectral shifts over time.

What are Milk Protein-Caffeine Interactions and Why Do They Matter?

For several reasons, it’s important to understand milk protein and caffeine interactions. They first influence the texture, taste and nutritional impact of coffee beverages. The robust milk proteins ensure that they continue to deposit a nice creamy mouthfeel, even in the presence of caffeine. In addition, these proteins could influence our body’s ability to absorb caffeine, meaning that how much caffeine is in our coffees affects how ‘kicked up’ we feel. The food and beverage industry may one day tailor coffee beverages to provide target flavors and caffeine release using these results.

MSE Supplies Tie-In: Infrared Spectroscopy Solutions

An extensive range of Spectroscopy Solutions from MSE Supplies are designed to support pioneering research across several disciplines including food science, material science, and chemistry. Laboratory Spectrometers of high precision allow researchers to see molecular interactions in a new level of detail, as in the recent investigation of milk and caffeine interactions. MSE Supplies is a line of tools that provide reliable insights at the molecular level so scientists can perform their research and discovery with the advanced capabilities they need.

FTIR Spectrometers (Fourier Transform Infrared Spectrometers) are used for molecular structure analysis and NIR Spectrometers (Near-Infrared Spectrometers) for capturing subtle chemical compositions in complicated samples are among our specialized spectroscopy solutions. In addition to FTIR and NIR options, MSE Supplies provides a range of spectroscopy technologies including UV-Vis Spectrometers and Raman Spectroscopy Solutions to meet a range of analytical needs. It triforces our comprehensive portfolio that allows researchers and industry experts to reach precise, reproducible results across applications to get to the frontier of their work.

This molecular exploration of milk proteins and caffeine has taught us that there’s a whole lot of chemistry in a simple cup of coffee. The study enables the understanding of the stability and behavior of milk proteins in coffee, holding the promise for potential food and beverage innovation. Similar tools like infrared spectroscopy offer limitless possibilities for future beverage engineering as our love for coffee.

MSE Supplies' advanced spectroscopy tools take your molecular spectroscopy to the next level. Visit our website; there you will be able to get a full overview of our product offerings; call us and speak with our experts to find the best solutions for your research, or follow us on Linkedin for some industry insights, product updates, and research tips!

Source: 

1. American Chemical Society. (2024, June 6). How milk proteins interact with caffeine in espresso. ScienceDaily. Retrieved October 28, 2024 from www.sciencedaily.com/releases/2024/06/240606152210.htm
2. Fani Madzharova, Tobias Weidner. Structure and Dynamics of Milk Proteins Interacting with Caffeine and Espresso Determined by Two-Dimensional Infrared Spectroscopy. ACS Food Science & Technology, 2024; DOI: 10.1021/acsfoodscitech.4c00070