Investigation of the effect of microwave and ultrasound applications on the extraction of nitrogenous substances in the cheese

Cheese undergoes physical, sensory, biochemical, and microbiological changes during ripening. The determination of cheese ripening is generally based on changes in nitrogenous compounds, which are typically extracted using pH 4.6/4.4 or water-based methods. This study investigates the applicability of innovative techniques such as ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) as alternatives to conventional methods for extracting nitrogenous compounds in cheese. MAE was performed at 90 W power with extraction times of 30, 40, 50, and 60 seconds, while UAE was conducted at a constant 60 amplitude (A) and 52 W power for 1, 5, 10, and 15 minutes. Conventional extraction requires a water bath for 1 hour; therefore, this study aimed to reduce extraction time while maintaining or improving extraction efficiency. Aged white cheese obtained from the market was used as a sample. The nitrogen content soluble in water, pH 4.6 buffer, and 12% TCA was determined, alongside peptide profiles analyzed by Urea-PAGE electrophoresis and high-performance liquid chromatography (HPLC), and total free amino acid content measured spectrophotometrically. MAE at 50 seconds achieved a 98.67% yield compared to the control, but efficiency decreased to 97.12% at 60 seconds. UAE provided a 93.25% yield at 1 minute but dropped to 70.91% at 15 minutes. In conclusion, both methods effectively reduced extraction time compared to conventional techniques; however, MAE proved to be more efficient than UAE.