Methodology to determine destruction of bacterial spores during extrusion cooking

Likimani, T.A.; Sofos, J.N.; Maga, J.A.; Harper, J.M.

Methodology to determine destruction of bacterial spores during extrusion cooking

1990

Likimani, T.A. | Sofos, J.N. | Maga, J.A. | Harper, J.M.

A methodology was developed for determining destruction of bacterial spores during extrusion cooking in a single screw extruder. Procedures were developed for estimating processing time at different screw speeds and calculation of "D-" and "z-values." The proposed methodology evaluated destruction of Bacillus globigii spores in 18% moisture corn/soybean mixture (70/30%, w/w). "D-value" expressed on the basis of average time at mass temperature greater than 95 degrees C during extrusion was the most conservative estimate of spore sensitivity. Times ranged from 1.7 sec at 115 degrees C to 6.6 sec at 100 degrees C maximum mass temperatures. These "D-values" resulted in a "z-value" of 25.3 degrees C, similar to that reported for the same strain with dry heat.

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