Optimization of process variables on physicochemical properties of milk during an innovative refractance window concentration

Abstract

An innovative refractance window (RW) concentrator was developed and used to concentrate milk samples at temperatures of 50–70°C and pressures of 0.4–0.8 bar. Optimum process conditions were found through response surface methodology to compare RW at optimal conditions with the conventional concentration (CC). Also, the effects of process parameters and their interactions on the RW process and product specifications were analyzed. According to the results, optimal RW conditions were a pressure of 0.4 bar and a temperature of 69.1°C. Besides, the energy efficiency and overall heat transfer coefficient of RW at optimal conditions were higher than those of CC by 125.2% and 15.3%, respectively. Compared to CC, RW reduced the concentration-time by 60.8% and minimized the changes in the chemical composition and color of the milk. RW process was found to be a time- and energy-saving concentration technique that can produce concentrated milk with improved quality. Practical applications Alternative concentration techniques that can reduce energy consumption and processing time while guaranteeing the quality retention of the product might be considered by the food industry. The innovative RW milk concentration method that was developed in the present study showed to be a promising time- and energy- saving concentration technique. This method was able to retain the quality characteristics of milk during the concentration process. Also, the optimization information provided in the present study can be used for developing upscaled units that can be used for the commercial concentration process of milk.