Acoustic properties of Chihuahua, manchego, and panela type cheeses, applying ultrasonic spectroscopy

In Mexico, there is a wide variety of cheeses which are produced according to their region of origin. The most common are the type cheeses: aged, white, Cotija, Chihuahua, fresh, mexican manchego, Oaxaca, panela and cottage cheese, to mention a few examples. From which, most are made from cow's milk, and in some cases from goat's or sheep's milk, depending on its type. However, it is very important to determine their qualitative and quantitative properties, as well as nutritional ones through the biological, physical and chemical characterizations that food has, applying various sources of stimulation such as acoustic, electrical, magnetic, mechanical, nuclear, optical, thermal, etc. In this paper, a study to determine the acoustic properties of Chihuahua, manchego and panela cheeses, applying acoustic spectroscopy in the ultrasound spectrum is presented. The products were purchased at a local store in the capital city of Chihuahua. The echoscope block of the GAMPT® acoustic tomograph with acoustic sensors at 2MHz was used to measure the acoustic phase velocity depending on the thickness, with a quasi-regular temperature of 16^oC of the environment. The method applied was by transmission with normal incidence. Measurements were performed in triplicate. The volumetric density and acoustic impedance of the cheeses as well as the rheological properties were determined by indirect method. The results show that the acoustic phase velocity of the Chihuahua, Manchego and Panela cheeses were VAF_Chi ≈ 1221.47m/s, VAF_man ≈ 1436.06m/s y VAF_pan ≈ 1142.28m/s, respectively. The volumetric density of the Chihuahua, Manchego and panela cheeses were r_Chi ≈ 1.1577gr/cm³, r_man ≈ 1.1138gr/cm³ y r_pan ≈ 1.7095gr/cm³ a 12.1^oC, respectively. In addition, the acoustic transmittance was explored, where a great attenuation was presented in all the products. It is possible that at a frequency of 2MHz the propagation of the wave through the cheese samples is attenuated as a sum of the absorption and scattering of the wave itself within the cheese structure.