Fundamental Food Microbiology, Third Edition - Fuad Fathir

CONTENTS
455
CHAPTER 32
Control by Heat
I. Introduction............................................................................................... 455
II. Objectives .................................................................................................456
III. Mechanism of Antimicrobial Action ........................................................457
IV. Influencing Factors ...................................................................................457
A. Nature of Food .................................................................................458
B. Nature of Microorganisms ...............................................................458
C. Nature of Process .............................................................................458
V. Mathematical Expressions ........................................................................459
A. Decimal Reduction Time (D Value) ................................................459
B. Thermal Death Time (TDT), Z Value, and F Value .........................460
VI. Methods ....................................................................................................461
A. Low-Heat Processing or Pasteurization ...........................................462
B. High-Heat-Processed Foods .............................................................463
C. Microwave Heating ..........................................................................464
VII. Conclusion ................................................................................................464
References............................................................................................................. 464
Questions ..............................................................................................................465
I. INTRODUCTION
The desirable effect of heat (from fire) on the taste of foods of animal and plant
origin, especially seeds, tubers, and roots, was probably accidentally discovered,
following a natural forest fire, by our ancestors long before civilization. They also
possibly recognized that heated foods did not spoil as rapidly as raw foods or cause
health hazards. Since then, particularly following the invention of pottery and ovens,
heat has been used to roast, boil, bake, and concentrate foods to improve taste and
to enhance shelf life (and probably safety). However, it was not until ca. 1810 that