7 TheLa~PanelPreliminao, Reporl:UK~ComemusConference on
P/antBia~.hno/ob'y 2.-4/~vember1994(19e;4),p. 3, 5cier, ce
Museum,london, UK8 ll~l.ayPanelPrelimiraryRelx~:UKNat~lCow*~em~ on
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November1994(1994),p. 10, Science
Maxseum, Londen,UK 12 Z-lo~dlxxe~tCozTm~egeOorton~ege~ui~o~d~Ug
(1993),HMSO,London,UK
ReviewHurdle technology was developed several years ago as a new
concept for the production of safe, stable, nutritious, tasty and
economical foods. It advocates the intelligent use of combinations
of different preservation factors or techniques ('hurdles') in
order to achieve multi-target, mild but reliable preservation
effects. Attractive applications have been identified in many food
areas. The present article briefly introduces the concept of hurdle
technology, presents potential applications and gives details on a
recently concluded study concerned with this topic and to which
scientists from 11 European countries have contributed.
Food preservation by hurdletechnology*Lothar Leistnerand
LeonG.M. Gorris
vative factors (hurdles) that any mict~3rganisms l~esent should
not be able to overcomet~-6. These hmdles may be temperatm~, water
activity (a,), pH, redox potential, preservatives, and soon. It
requites a c e n a ~ amonnt of effort from a micromganism to
overcome each hurdle. The 'higher" the hurdle, the greater the
effort (i.e. the The spoilage and poisoning of foods by
micrnorgenisms larger tbe number of orgenisms ueeded to overeome
it). is a problem that is not yet under adequate control, Some
hurdles, like pasteurization, can be high for a despite the range
of preservation techniques available large number of different
types of (e.g. freezing, blanching, pasteurizing and canning). In
whereas others, like salt content, have a less strong fact, the
current Consumer demand for more natural and effect or the effect
is limited in the range of types of fresh-like foods, which urges
food m~nufactorers to use microorganisms it effects. only mild
preservation techniques (e.g. refrigeration, The fact that a
combination of weservafive factors modi~ed-atmosphere packaging and
biocoaservation), influences the microbial stability and safety of
foods has should make this problem even greater. Thus, for the been
known for many centuries. Tbe coueopt is mole or benefit of food
manufacturers there is a strong need for less unconsciously used in
many traditional foods, esnew or improved mild l~..~-rvation
methods that allow pecinlly in the developing countries. It was
re-invented for the production c_ fresh-like, but stable and safe
some 15 years ago in the meat industry where the confoods. The
concept of hurdle technology is not new but seinus employment of
hurdles was found to be highly favonrable for the production of
shelf-stable sansages2. addresses this need in full '.2. Hurdle
technology (also called combined methods, The concept is now ready
to be iatxedueed for u ~ with combined processes, combination
preservation, combi- a much wider range of food products, including
fruits ve~, t,~-y products,dairy products, fish, nation techniques
or barrier technology) advocates the deliberate combination of
existing and novel preser- and so on. Several novel preservative
factors (e.g. vation techniques in order to establish a series of
preser- gas packaging, biueooservation, hacterincins,ultraldgh-
pressure treatment, edible coatings, etc.) that speciti*Revised
versiond an a~icle ~l~ished in 1994 in Vaed/n~m/dde~n- c~lly
fucilltate this development have been assessed7. ~chnotog~ 27(21),
15-17 [in Dutch] and AUTECNA4, 17-19 [in Hurdle technology is a
crucial concept for the mild Portuguese]. Weservation of foods, as
the hm'dles in a stable product concertedly control microbial
spoilage and food poisont e a r teMner is at the Federal Centre for
Meat Research, E.C. Baumannstrasse D-95326Kulmbach,Germany.L,'~
C~M.Gm'fis tag, leaving desiged fennentation processes unaffected.
20, (curespondin8 author) is at the Institm for/~mechnol~.~: Re~,.h
Because of their c o n c e n ~ sometimes synergistic ef(ATO-DLO),
BornseKeeg59, PO Box 17, NL-6700AA Waseningen,The fect. the
individual hurdles may be set at lower intensiNethedands
+31-8370-12260; (fax: e-mail:L.G~.CORRISt~TOAGRO.NU. ties than
would be required if only a single hurdle were Trends in Food
Science & Technoto~/FebruaTy 1995 [VoL 6i re.s, ~.~.r sc~e
L~ogZ4-Z2On~Og.SO 41
in Fig. la represents a food containing six hat'dles: high
temperature during processing (F value), low temperature during
storage (t value), low water activity (a~), acidity (pH) and low
redox potential (Ell), as well as preservatives (pres.) in the
Im~uct. Some of the microorganisms present can overcome a number of
hurdles but none can jump over all the hurdles used together. r~mp~
of ~hehm~ e f ~ A food pgodect is mlcrobiologically stable and safe
Thus the food is stable and safe. This example is only a beceme of
the presence of a set of hurdles ~ is theorelical case, because all
hurdles are depicted as havs p e c ~ for t~e pmicu~r product, in
terms of the naune ing the same intensity, which is rarely the case
in praeend suengt~ of t~e~r effecL T o g ~ , t~ese bpadles keep
rice. More likely, hurdles are of different intensity, as in
spoilage o~ pathogenic n ~ c m m ' g ~ m s under control the second
exemple (see Fig. lb), where a , and preservapH b c c a ~ Ibee
n~moorgmdsms cannot overcome ('jump fives m-e the main hurdles and
storage t e ~ , over') all of the hm'~es p~.eent. Exmnples of sets
of and Eh are minor hurdles. If there are only a few microhurdtes
are ~lustreted by Figs la-e. The example shown orgadsms l ~ n t at
the smt (see Rg. lc), fewer dilferent
used as the Weserva~ion t e c b ~ u e . The application of ~s
co~ ~ ~ v e n very s u c c e s s ~ as en appropda~e combin~on of
hurdles achieves microb~l stability and safety and also stabilizes
Ihe sensory, nutritive and eco~n~ ~ e s of a food~ .
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