Evaluation of thermal and nonthermal treatment of margarine: Pasteurization process efficiency, kinetics of microbial destruction, and changes in thermophysical characteristics

Abstract

The objective of this study was the thermophysical characterization and microbial evaluation of the commercial margarine production process. Thermal destruction of Escherichia coli (K-12) was characterized between 60 and 70°C with a decimal reduction time (D value) between 4.44 and 0.22 min and a Z value of 7.72°C. Pulsed light treatment as a nonthermal alternative was used for comparison; however, the effectiveness was very weak with a 90% surface decontamination yield after 20 s of high-intensity pulsed light treatment. Rheological studies showed a two-stage flow behavior due to the melting phenomenon of margarine and the use of the Arrhenius model yielded an activation energy of 186.3 and 15.0 (kJ/mol) before and after a phase transition point at 36.6°C, respectively. The differential scanning calorimetric studies showed three main peaks related to the melting of unsaturated fats (−22.0°C), melting of brine phase (−6.1°C), and melting of saturated fats (31.3°C). The holding tube length was calculated based on the physical properties of margarine and different Reynolds numbers. Practical applications Margarine production is still a growing industry and nowadays many novel approaches are used for pasteurization purposes and hence the evaluation of process efficiency and product characterization is desirable. In this regard, the present work provides helpful data for te margarine production by adjusting a practical approach toward evaluating the thermal pasteurization efficiency. In addition, the evaluated thermophysical characterization of margarine presents a scientific basis for the research and development in terms of product formulation and thermal/nonthermal process adaptations.