FRESH PERSPECTIVES
Figure 7 - Cycle after controlled nucleation using FreezeBooster technology. The primary drying time was reduced to 30 hours.
The combination of controlled nucleation with controlled heat fl ow during freezing resulted in lower product temperatures during primary drying due to lower cake resistance, thus allowing the shelf temperature to be increased and shorter primary drying times achieved.
Another powerful feature of measuring the heat fl ow is that the End of Primary Drying can be detected. As can be seen in Figures 9 and 10, the heat fl ux measurement was in direct agreement with the pressure
Figure 9 - Primary drying post-controlled nucleation and AccuFlux ice crystal growth control, shelf temperature was raised to -12°C. A 46.3% reduction in primary drying time.
Figure 8 - Cycle with controlled nucleation using FreezeBooster and then AccuFlux was used to control the crystal growth at an arbitrary level. The primary drying time was reduced to 28 hours. It is very important to note that the product temperature ran at 4° to 5°C lower. AccuFlux produced an ice crystal structure that had a far lower cake resistance.
Figure 10 - Further reduction in primary drying time using AccuFlux to control the shelf temperature based on the product temperature, which was calculated using the heat fl ux data. The result is a 53% reduction in overall primary drying time.
The ability to monitor and control the freezing process enables the operator to develop a fully controllable and repeatable ice and cake structure. Further testing and fi eld results will provide more information on the best heat fl ow control levels and profi les during freezing to produce the best pore structure and lowest cake resistance for a specifi c product. If desired, controlling the heat fl ow can also be used to produce a consistent collapsed structure as well.
73 American Pharmaceutical Review | Fresh Perspectives 2013
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92