Optimization of recombination of milk at different fat levels in a small volume universal disperser unit

Recombined milk (RM) can be prepared by blending of butteroil, skim milk powder and water and used for variety of purposes in dairy industry. The present work was undertaken to investigate the feasibility of a custom designed and fabricated universal disperser unit for the preparation of recombined milk. Water, SMP and butteroil were used to manufacture the recombined milk. Three levels of fat viz 1.5%, 3.0% and 4.5% were evaluated to study the effect of fat content on the recombination efficiency of the universal disperser using a high shear saw tooth impeller to impart the required shear and disperse the fat in water–SMP matrix to form a stable emulsion. Two independent parameters i.e. temperature at three different levels (20, 35 and 50 °C) and impeller speed (10,000, 15,000 and 20,000 rpm) were selected for the study. All operations were carried out in heating cum process vessel having working capacity of 3 L. The efficiency of the operation was judged based on the dependent parameters namely, mixing time, mixing index, creaming index, power consumption and overall acceptability. Experiments were designed as per RSM in Design Expert V.10.0 software and results obtained were optimized and predicted solutions were compared with observed data. From the study, the optimal combinations for preparation of recombined milk were obtained as 1.5% Fat RM (17,820 rpm, 48 °C), 3.0% Fat RM (15,701 rpm, 48 °C) and 4.5% Fat RM (15,459 rpm, 48 °C).