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the stability and safety o f most preserved foods is based on the application o f

several preservation methods used in combinations, and this is true for foods o f

industrialized as well as of developing countries. More recetly, the underlying

principles o f the traditional food preservation methods have been defined (i.e., F,

t, aw, pH, Eh, competitive flora, various preservatives), and effective limits o f these

factors for microbial growth, survival, and death were established. Food

preservation and also food quality depend in most cases on the empirical and now

more often on the deliberate and intelligent application of combined preservative

factors, i.e. on so-called hurdle technology. It also became obvious that future

food preservation methods (i.e. the pulsed technologies, as well as irradiation) are

most effective in combination with additional hurdles. Thus, hurdle technology is

also the key o f food preservation in the future. Furthermore, basic aspects o f hurdle

technology (i.e. homeostasis, metabolic exhaustion, and stress reactions o f

microorga-nisms as well as multitarget preservation of food) have been recognized

to be o f fundamental importance for food preservation and are increasingly studied

in relation to hurdle technology.

Different aspects of improvements o f traditional foods and in the development

o f novel foods via hurdle technology have been covered recently in numerous

articles and book chapters. However, the book “Hurdle Technologies: Combination

Treatments for Food Stablity, Safety and Quality” is the first work on hurdle

technology in which all aspects, the possibilities and limitations o f hurdle

technology as well as the theoretical background, are comprehensively outlined

and evaluated (Leistner & Gould, 2002). This book has been published in 2002 by

Kluwer Academic/Plenum Publishers, New York, USA.

Predictive Microbiology (PM)

Use of predictive mathematical models, which forcast with aid of computers, the

behaviour of microorganisms in foods, has attracted much attention in the last decade,

especially in relation to food safety. Earlier models (e.g. for inactivation o f

microorganisms by heat) have been inactivation models. It is only in the last decades

that models have been developed for the growth of microorganisms in foods. These

kinetic growth models have targeted the major food poisoning microorganisms and

effects of the most common factors for food preservation (i.e., storage temperature,

pH, aw, and few preservatives). Since in many foods preservative factors (hurdles) are

active that are not (yet) covered by predictive microbiology the answers received with

the available models are often too conservative (“fail/safe”). Furthermore, these kinetic

models are of importance mainly for chilled foods with limited shelflives, but they are

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