September is National Italian Cheese Month! Did you know that there are over 450 varieties of Italian cheeses? The most popular in the United States is mozzarella- the average American eats 11 pounds of this soft, melty cheese in a year! 1
Raman spectroscopy has been routinely used to monitor the quality of foods such as cheese and other dairy products.2-4 Some Italian cheeses such as Parmigiano-Reggiano are certified with protected designation of origin (PDO) status, which identifies products that are manufactured in a specific geographical area using the recognized knowledge of local producers and ingredients from the region concerned. Products labeled as PDO are often susceptible to counterfeiting for economic gain. Using Raman spectroscopy, we can develop analytical models to authenticate PDO products, and potentially identify fake ones.
Figure 1 shows Raman spectra from multiple Italian cheeses collected using an i-Raman Plus 785 system. The bands observed could potentially be used to monitor fat and protein content in cheeses.
Food products are often quite heterogeneous. Figure 2 shows the Raman spectra collected from two different spots on Parmigiano-Reggiano cheese. Although they are both from the same piece of cheese, they are quite distinct from each other! The purple spectrum was collected from a small, crystalline spot; the brown spectrum was collected from a spot with a smooth surface. The purple spectrum is consistent with Raman signal from L-tyrosine. Tyrosine is an amino acid that crystallizes on the interior of common hard cheeses. These tyrosine crystals contribute to the delicious flavor and crunchiness of Parmigiano-Reggiano cheese!
1. National DayCalendar: National Italian Cheese Month-September. https://nationaldaycalendar.com/national-italian-cheese-month-september/ (accessed September 20, 2021). 2. M. K. Nieuwoudt, S. E. Holroyd, C. M. McGoverin, M. C. Simpson, and D. E. Williams, J. Dairy Sci. 99, 1-11 (2016). 3. S. Liu, A. Kannegulla, X. Kong, R. Sun, Y. Liu, R. Wang, Q. Yu, and A. Wang, Spectrochim. Acta A Mol. Biomol. Spectrosc. 231, 118130 (2020). 4. M. Li Vigni, C. Durante, S. Michelini, M. Nocetti, and M. Cocchi, Foods. 9, 1563 (2020). 5. Z-Y. Zhang, Journal of Spectroscopy. 2020, 7 pages (2020).