Methodology to Determine Destruction of Bacterial Spores during Extrusion Cooking

Authors

  • T.A. LIKIMANI,

    1. Author Sofos is with the Dept. of Animal Sciences and Dept. of Food Science & Human Nutrition, Author Maga is with the Dept. of Food Science & Human Nutrition, and author Harper is Vice President for Research, Colorado State Univ., Fort Collins, CO 80523. Author Likimani's present address: Dept. of Food Technology & Nutrition, Univ of Nairobi, P.O. Box 29053, Kabete, Kanva.
    Search for more papers by this author
  • J.N. SOFOS,

    1. Author Sofos is with the Dept. of Animal Sciences and Dept. of Food Science & Human Nutrition, Author Maga is with the Dept. of Food Science & Human Nutrition, and author Harper is Vice President for Research, Colorado State Univ., Fort Collins, CO 80523. Author Likimani's present address: Dept. of Food Technology & Nutrition, Univ of Nairobi, P.O. Box 29053, Kabete, Kanva.
    Search for more papers by this author
  • J.A. MAGA,

    1. Author Sofos is with the Dept. of Animal Sciences and Dept. of Food Science & Human Nutrition, Author Maga is with the Dept. of Food Science & Human Nutrition, and author Harper is Vice President for Research, Colorado State Univ., Fort Collins, CO 80523. Author Likimani's present address: Dept. of Food Technology & Nutrition, Univ of Nairobi, P.O. Box 29053, Kabete, Kanva.
    Search for more papers by this author
  • J.M. HARPER

    1. Author Sofos is with the Dept. of Animal Sciences and Dept. of Food Science & Human Nutrition, Author Maga is with the Dept. of Food Science & Human Nutrition, and author Harper is Vice President for Research, Colorado State Univ., Fort Collins, CO 80523. Author Likimani's present address: Dept. of Food Technology & Nutrition, Univ of Nairobi, P.O. Box 29053, Kabete, Kanva.
    Search for more papers by this author

  • This work was supported by the Agricultural Experiment Station of Colorado State University and by the Swiss Development Cooperation.

ABSTRACT

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 >95°C during extrusion was the most conservative estimate of spore sensitivity. Times ranged from 1.7 sec at 115°C to 6.6 sec at 100°C maximum mass temperatures. These “D-values” resulted in a “z-value” of 25.3°C., similar to that reported for the same strain with dry heat.

Ancillary