Hurdle technology is a method of ensuring thatpathogens infood products can be eliminated or controlled. This means the food products will be safe for consumption, and theirshelf life will be extended. Hurdle technology usually works by combining more than one approach. These approaches can be thought of as "hurdles" the pathogen has to overcome if it is to remain active in the food. The right combination of hurdles can ensure all pathogens are eliminated or rendered harmless in the final product.[1]
Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles which secures themicrobial safety and stability as well as theorganoleptic and nutritional quality and the economic viability offood products.[2] The organoleptic quality of the food refers to its sensory properties, that is its look, taste, smell and texture.
Examples of hurdles in afood system are high temperature during processing, low temperature during storage, increasing theacidity, lowering thewater activity orredox potential, or the presence ofpreservatives. According to the type of pathogens and how risky they are, the intensity of the hurdles can be adjusted individually to meet consumer preferences in an economical way, without compromising the safety of the product.[1]
Not all hurdles are used simultaneously or applied to every food product. Their effectiveness depends on the intensity of application—higher intensity improves microbial stability, while excessive intensity may negatively impact food quality. For example, traditional heat treatment methods like pasteurization can degrade thermolabile bioactive compounds in fruit juices, reducing their nutritional value. As an alternative, non-thermal preservation techniques based on the hurdle concept offer a promising solution, ensuring food safety while maintaining quality, nutritional integrity, and consumer appeal.[3]
Each hurdle aims to eliminate, inactivate or at least inhibit unwanted microorganisms. Common salt ororganic acids can be used as hurdles to control microbials in food. Many natural antimicrobials such asnisin,natamycin and otherbacteriocins also work well. As do essential oils derived from rosemary or thyme.[4][5]
| Principal hurdles used for food preservation (after Leistner, 1995)[6][7] | ||
|---|---|---|
| Parameter | Symbol | Application |
| High temperature | F | Heating |
| Low temperature | T | Chilling,freezing |
| Reducedwater activity | aw | Drying,curing,conserving |
| Increasedacidity | pH | Acid addition or formation (pickling) |
| Reducedredox potential | Eh | Removal of oxygen or addition ofantioxidants likeascorbate |
| Biopreservatives | Competitiveflora such asmicrobialfermentation | |
| Otherpreservatives | Sorbates,sulfites,nitrites | |
"Traditionally,fermented seafood products common in Japan, provide a typical example of hurdle technology. Fermentation ofsushi employs hurdles that favour growth of desirable bacteria but inhibit the growth of pathogens. The important hurdles in the early stages of fermentation are salt and vinegar. Raw fish is cured in salt (20–30%, w/w) for one month before being desalted and pickled in vinegar. The main target of these hurdles isC. botulinum. Growth oflactic acid bacteria during fermentation results in acid production from metabolism of added sugars and rice. The result is a pH hurdle important in controlling growth ofC. botulinum."[1]
| Types of hurdles used for food preservation (from Ohlsson and Bengtsson, 2002)[7][8] | ||
|---|---|---|
| Type of hurdle | Examples | |
| Physical | Aseptic packaging, electromagnetic energy (microwave, radio frequency, pulsed magnetic fields, high electric fields), high temperatures (blanching,pasteurization,sterilization,evaporation,extrusion,baking,frying),ionizing radiation, low temperature (chilling, freezing),modified atmospheres, packaging films (includingactive packaging, edible coatings), photodynamic inactivation,ultra-high pressures, ultrasonication, ultraviolet radiation | |
| Physicochemical | Carbon dioxide, ethanol,lactic acid,lactoperoxidase, low pH, lowredox potential, lowwater activity,Maillard reaction products, organic acids, oxygen, ozone, phenols, phosphates, salt, smoking, sodium nitrite/nitrate, sodium or potassium sulfite, spices and herbs,surface treatment agents | |
| Microbial | Antibiotics,bacteriocins, competitive flora, protective cultures | |
There can be significantsynergistic effects between hurdles. For example,Gram-positive bacteria include some of the more important spoilage bacteria, such asClostridium,Bacillus andListeria. A synergistic enhancement occurs ifnisin is used against these bacteria in combination with antioxidants, organic acids or other antimicrobials. Combining antimicrobial hurdles in an intelligent way means other hurdles can be reduced, yet the resulting food can have superior sensory qualities.
