flexibility, as seen in the Extru-Tech Model E975 Extrusion System, is well suited for these types of applications. Reference the April 2008 E975 issue of The Extru-Technician for further details.

Reduced cook levels (starch gelatinization)

Tip: An effort to maximize cook levels requires systematic testing. First you must preface the trials by determining where your extruder process management currently resides in relation to the water curve. As water initially is added into the feed and gradually increased, the feed will reach a point of maximum cook/expansion.

If more water is added from this point, a reduction in cook/expansion will be experienced as the water will have a cooling affect on the feed.

Figure 2 (p. 6) shows this water injection rate relative to the percent of starch gelatinization (cook), resulting in the water curve.

The final step is to adjust the water injection so the summation of total water and the additional moisture from the meat does not exceed the apex of your water curve. This procedure will render a good starting point. Performing a test run with varying levels of moisture around the apex will finalize and support the data collected.

Again, using the appropriately sized DCC with an advanced paddle configuration will help maximize retention time and residence time distribution to allow

Figure 2: Effect of water on gelatinization

100

90

Starch Gelatinization (%)

80

70

60

50

40

30

20

10

0

0

4 8 12 16

Water Injection (% to Feed Rate)

20

As water is initially added into the feed and gradually increased, the feed will reach a point of maximum cook/expansion. If more water then is added, a reduction in cook/expansion will be experienced as the water will have a cooling affect on the feed. This curve shows this water injection rate relative to the percent of starch gelatinization (cook).

September 2008 Extru-Technician 7