Thermal imaging for estimating melting point in cheese: A cost-effective alternative to rheology

The melting characteristics of cheese play a pivotal role in determining functional performance in various applications. Measuring the meltability and melting point of cheese is a challenge and requires sophisticated equipment, a laboratory setup, and personnel training, and the cost can be prohibitive. Over the years, many tests have been developed to determine the meltability or melting point of cheese. Currently, the melting point of cheese is measured using a specialized instrument, a rheometer for dynamic stress rheology values, to calculate the transition temperature (tan δ). It measures the transition of cheese from the solid to the viscous phase as the cheese is heated. However, the test is time-consuming. A thermal infrared (IR) image camera and software analysis can be used to quickly measure cheese's meltability and melting point. The study was designed to develop a method to estimate the melting point of cheese using a thermal imaging camera, providing a more practical and cost-effective alternative to conventional rheological analysis. Commercial samples of cheeses, including natural Cheddar and various processed cheese slices, were procured from the market. The samples were analyzed for meltability using the tube melt, Schreiber melt, and rheological (G', G″, and tan δ) tests. The thermal IR image camera test method was developed, and the data were processed using software to determine the melting point. The experiment was conducted in triplicate using different lots of cheese. The collected data were statistically analyzed using RStudio. The melt temperature points from the thermal image camera after 1 min were then correlated with the rheological analysis, and the R² was calculated. The melt characteristics differed significantly according to cheese type. The melting points (tan δ) obtained using a rheometer for cheeses varied between 46.66°C and 64.33°C, and the corresponding values from image analysis were between 48.07°C and 64.61°C. The R² values for the correlations ranged from 0.804 to 0.813, demonstrating a strong relationship between the rheological and image analysis methods. Additionally, thermal images identify the cheese's melting point and heat distribution. The detailed interpretation aids researchers in understanding the thermal properties and structural changes during melting, while also providing sales professionals with informative visual representations to effectively showcase product quality and performance. In conclusion, the study demonstrated that a thermal imaging method provides a practical, quick, and cost-effective approach for estimating the melting point in cheese compared with conventional rheological analysis and can be used on-site.