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{{Short description|Food production safety method}}
'''Hurdle technology''' is a method of ensuring that [[pathogen]]s in [[food product]]s can be eliminated or controlled. This means the food products will be safe for consumption, and their [[shelf 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.<ref name="Alasalvar" />

Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles which secures the [[microbial]] safety and stability as well as the [[organoleptic]] and nutritional quality and the economic viability of [[food product]]s.<ref>Leistner I (2000) [http://envismadrasuniv.org/Physiology/pdf/Basic%20aspects%20of%20food%20preservation.pdf "Basic aspects of food preservation by hurdle technology"] ''International Journal of Food Microbiology'', '''55''':181–186.</ref> The organoleptic quality of the food refers to its sensory properties, that is its look, taste, smell and texture.

Examples of hurdles in a [[food system]] are high temperature during processing, low temperature during storage, increasing the [[acidity]], lowering the [[water activity]] or [[redox potential]], or the presence of [[preservative]]s. 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.<ref name="Alasalvar">Alasalvar C (2010) [https://books.google.com/books?id=l-APOWUVp-8C&pg=PT232&dq=%22hurdle+technology%22|%22hurdle+technologies%22&hl=en&ei=5GSFTaTGCJCSuAOj66zGCA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDgQ6AEwAg#v=onepage&q=%22hurdle%20technology%22|%22hurdle%20technologies%22&f=false ''Seafood Quality, Safety and Health Applications''] John Wiley and Sons, Page 203. {{ISBN|978-1-4051-8070-2}}.</ref>

==Hurdles==
Each hurdle aims to eliminate, inactivate or at least inhibit unwanted microorganisms. Common salt or [[organic acid]]s can be used as hurdles to control microbials in food. Many natural antimicrobials such as [[nisin]], [[natamycin]] and other [[bacteriocin]]s, and essential oils derived from rosemary or thyme, also work well.

{| class="wikitable"
|-
! colspan="3"  style="text-align:center; width:560px;"| Principal hurdles used for food preservation (after Leistner, 1995)<ref>Leistner L (1995) [https://books.google.com/books?id=6a_dbGRoiWIC&q=Principles+and+applications+of+hurdle+technology "Principles and applications of hurdle technology"] In Gould GW (Ed.) ''New Methods of Food Preservation'', Springer, pp. 1–21. {{ISBN|978-0-8342-1341-8}}.</ref><ref name="Lee">Lee S (2004) [http://www.internetjfs.org/articles/ijfsv4-3.pdf "Microbial Safety of Pickled Fruits and Vegetables and Hurdle Technology"] {{Webarchive|url=https://web.archive.org/web/20110901001910/http://www.internetjfs.org/articles/ijfsv4-3.pdf |date=2011-09-01 }} ''Internet Journal of Food Safety'', '''4''': 21–32.</ref>
|-
! Parameter
! Symbol
! Application
|-
| High temperature
| style="text-align:center;"| F
| Heating
|-
| Low temperature
| style="text-align:center;"| T
| [[Refrigeration|Chilling]], [[Frozen food|freezing]]
|-
| Reduced [[water activity]]
| style="text-align:center;"| a<sub>w</sub>
| [[Drying]], [[Curing (food preservation)|curing]], [[Conserve (condiment)|conserving]]
|-
| Increased [[acidity]]
| style="text-align:center;"| [[pH]]
| Acid addition or formation ([[pickling]])
|-
| Reduced [[redox potential]]
| style="text-align:center;"| E<sub>h </sub>
| Removal of oxygen or addition of [[antioxidants]] like [[ascorbate]]
|-
| [[Biopreservative]]s
|
| Competitive [[flora]] such as [[microbial]] [[Fermentation (food)|fermentation]]
|-
| Other [[preservative]]s
|
| [[Sorbate]]s, [[sulfite]]s, [[nitrite]]s
|}

"Traditionally, [[Fermentation (food)|fermented]] seafood products common in Japan, provide a typical example of hurdle technology. Fermentation of [[sushi]] 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 is ''[[C. botulinum]]''. Growth of [[lactic 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 of ''C. botulinum''."<ref name="Alasalvar" />

{| class="wikitable"
|-
! colspan="3"  style="text-align:center; width:560px;"| Types of hurdles used for food preservation (from Ohlsson and Bengtsson, 2002)<ref name="Lee" /><ref>Ohlsson T and Bengtsson N (2002) [https://books.google.com/books?id=0qw8lA1R9R0C&q=%22Minimal+Processing+Technologies+in+the+Food+Industry%22 "The hurdle concept"] ''Minimal Processing Technologies in the Food Industry'', Woodhead Publishing, pp. 175–195. {{ISBN|978-1-85573-547-7}}.</ref>
|-
! Type of hurdle
! Examples
|-
| Physical
| [[Aseptic]] packaging, electromagnetic energy (microwave, radio frequency, pulsed magnetic fields, high electric fields), high temperatures ([[Blanching (cooking)|blanching]], [[pasteurization]], [[Sterilization (microbiology)|sterilization]], [[evaporation]], [[Extrusion#Food|extrusion]], [[baking]], [[frying]]), [[ionizing radiation]], low temperature (chilling, freezing), [[Modified atmosphere/modified humidity packaging|modified atmospheres]], packaging films (including [[active packaging]], edible coatings), photodynamic inactivation, [[Pascalization|ultra-high pressures]], ultrasonication, ultraviolet radiation
|-
| Physicochemical
| Carbon dioxide, ethanol, [[lactic acid]], [[lactoperoxidase]], low pH, low [[redox potential]], low [[water 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]]
| [[Antibiotic]]s, [[bacteriocin]]s, competitive flora, protective cultures
|}

==Synergistic effects==
There can be significant [[synergistic]] effects between hurdles. For example, [[Gram-positive bacteria]] include some of the more important spoilage bacteria, such as ''[[Clostridium]]'', ''[[Bacillus]]'' and ''[[Listeria]]''. A synergistic enhancement occurs if [[nisin]] 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.

==See also==
* [[Biopreservation]]

==References==
{{reflist}}

{{food preservation}}

[[Category:Food preservation]]