The Hurdle Concept

摘要: In the past, in describing methods used for preservation of foods, general expressions like heating, drying, salting, acidifying, fermenting, etc., were used. After principles behind these measures became known, i.e., how to quantify heating by F values, drying water activity, acidifying pH and titratable acidity, treatments could be quantitatively expressed values F, awpH, Eh, etc. Subsequently, much work has been done define critical limits growth, survival, death significant microorganisms relation (see Tables 1-4 1-6, 1-8), such data have provided basis many improvements food techniques. However, it obvious that most foods not just one preservative factor is decisive microbial stability safety, but a combination factors. For example, was pointed out mild reduction awin with other processes or factors may employed produce foodstuffs are microbiologically stable without need extreme awthat necessary if this alone (Loncin, 1976). The called hurdles (Leistner & Rodel, 1976), so-called hurdle effect introduced (Leistner, 1978), widely accepted as an illustration complex interactions several inhibitory foods. It appreciated word “hurdle” might imply superficially asequenceof effects.However,the concept become well-understood include technique span whole range possible effects,include some sequential,but more act unison,and operation intrinsic,extrinsic,process-based,and implicit particular food(see chapter 1).From understanding effect,hurdle technology derived(Leistner,1985),which goal understand why certain safe stable,but improve quality optimization intelligent modification present.An additional step focus design on safety also sensory nutritional product,i.e.,ontotal quality(Leistner,1994a).This will describe detail developments,and mention further dimensions which explored future.