The development of an auto-analyzer device for fast and economic analysis of pH, total acidity and fat ratio improving the food safety and quality in dairy industry

In this study; A new simultaneous method measuring total acidity and pH of milk is described. Three composite pH electrodes in different composition and production phase were tested. Potentiometric performance characteristics of the pH electrodes in the stagnant environment were examined by using a computer-controlled multi channel potentiometer system. The best potantiometric performance was obtained from the electrode prepared by combining 12.50% treated trimethylhydroquinone, 12.50% untreated trimethylhydroquinone, 25% graphite and 50% polymethyl methacrylate. A flow-cell has been designed for pH and reference electrodes for the sequential injection analysis. Three different miniature columns were applied in the flow-line to improve the efficiency of total acidity measurement in the sequential injection analysis system. Some main parameters such as volume of injection, flow-rate of carrier, length of miniature column, length of tubing as they are asumed highly influential in simultaneous measurement of total acidity, pH and fat ratio analyses were examined for the optimization. During the trials, mobile phase concentration and sampling rate were also taken into account to obtain best titration peak curve. The mini boutirometer designed for the flow system is integrated into the system. Finally the developed sequential injection analysis system was applied to different milk samples for total acidity, pH and total fat ratio analyses. Results obtained by both methods were analyzed by SPSS software. The obtained results by the developed method were compared with the results obtained by classical titration method and found to be compatible with each other. pH results of milk samples that they are simultaneously measured in the system developed were also compared with the results obtained by a commercial glass pH electrode. The obtained pH results were also found to be compatible with each other. Fat ratio results of milk samples that are obtained by Gerber method, fount to be compatible with each other. In sight of obtained data, the method developed in the present study will ensure some advantages such as economy, fast and pricise measurement of pH, total acidity and fat ratio simultaneously in low volume milk samples, and might have potential to replace by the conventional methods.