Quality Control During Processing of Feta Cheese—NIR Application

This work examines the possibility of using near infrared (NIR) spectroscopic method for the production process control of the traditional Greek feta cheese. A NIR apparatus (Instalab 600-Dickey–John) was employed. Moisture, fat and protein determinations were selected as calibration set for the instrument. Samples were drawn from well-defined critical points of production. In all the samples conventional chemical methods were applied for the quantitative determination of the above ingredients. Results were compared with the respective data from NIR apparatus. All data were processed by a suitable computer program so that the calibration constants could be calculated and then stored in the apparatus. Their accuracy was verified using an independent set of analyzed samples. Because the NIR apparatus used in this work was not suitable for liquid products, a novel technique was developed using “quartz fine granular washed and calcined GR” (pro analysi). This technique proved to be reliable with a significant accuracy. From this study it can be concluded that NIR technique can be applied successfully for the on-line quality control of the feta cheese production. The reliability, significant reduction of human errors, precision and quickness of NIR spectroscopy experienced during this work, support the implementation of this method.