Hurdle Technology in Food Preservation - Minimally Processed Foods - page 18

limit to stop all microbial process, thus only salt as a hurdle could be impossible to
implement due to the negative impact on health and sensory. For this reason , most
of the cases salt is used in combination with other hurdles. Most processed meat
products contain sodium chloride from 2.8 % in cooked sausages to 4.5 % in cured
meat products (Komarik et al. 1974 ) and have been maligned as a heavy salt con-
tributor to the diet. However, in many products salt in combination with other hur-
dles showed high potential.

2.3 Progress in Developing Guidelines

The stability guidelines are mainly based on the pH, water activity, and thermal
processing. FDA's Good Manufacturing Practice Regulations governing the pro-
cessing requirements and the classification of foods are shown in Fig. 2.1 (Johnston
and Lin 1987 ). Low acid (i.e. high pH) foods packaged in hermetically sealed con-
tainers must achieve commercial sterility conditions either by retorting or combined
treatment of pasteurization and water activity or a combined treatment of pasteuri-
zation and acidification. It could be seen that pH 4.6 and a w 0.85 are the critical
limits. In 1962 the US Public Health Service in the “Food Service Sanitation
Manual” issued the potentially hazardous food (PHF) as any perishable food which
consists in whole or in part of milk products, eggs, meat, poultry, fish or other ingre-
dients capable of supporting the rapid and progressive growth of infectious or toxi-
genic microorganisms. The progress of the definition of PHF is discussed in the
IFT/FDA Report (IFT/FDA 2003 ). FDA Food Code in 1999 defined PHF food as it

Fig. 2.1 FDA Good Manufacturing Practice Regulations governing processing requirements and
classification of foods (Adapted from Johnston and Lin 1987 )