Hurdle technology is a method for preserving fish and other food products by combining multiple preservation factors to control pathogens and extend shelf life. This approach addresses the challenges of microorganism resistance and ensures food safety while maintaining sensory and nutritional quality. Key hurdles include temperature control, reduced water activity, increased acidity, and the use of preservatives, all of which work together to inhibit microbial growth.

1. Hurdle Technology In
Fish Preservation…

2. NEED FOR HURDLE TECHNOLOGY
 The quality food and food product is very important to the people or consumer.
There are two important reasons because of which we need the hurdle technology
 1. Consumers are demanding for fresh, natural and minimally processed food
products.
 2. Ongoing trend has been eat out and to consume ready to eat food.
 Fish is Perishable commodity and is prone to deterioration. This deterioration can
be provoked by microorganisms and/or by a variety of physico-chemical reactions
that take place after harvesting. The priority of any preservation process however, is
to minimize the potential for the occurrence and growth of food spoilage and food
poisoning microorganisms.

3.  Since ages Man has been using various methods and factors to
control these microorganisms .
 Examples of factors are acidity (i.e. lowered pH); limitation of water
available for growth i.e. reduction in water activity; presence of
preservatives; high temperatures, and low temperatures, limitation
of nutrients; ultraviolet radiation etc.(These were used individually)
 Unfortunately, microorganisms have evolved different mechanisms
to resist the efficiency of these factors. These mechanisms, called
“Homeostatic mechanisms to ensure that key physiological
activities and parameters in the microorganism remain relatively
unchanged, even when the environment around the cell is different
and greatly perturbed. So, to be effective, the preservation factors
must overcome the microbial homeostatic resistance.

4. What is Hurdle Technology…?
 Hurdle technology is a method of ensuring that
pathogens in food products 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.
 The microbial safety and stability of most food are
based on an application of preservative factors called
hurdles.

5. Hurdle Technology…
 Hurdle technology has been defined by Lothar Leistner in 1976 as:-
Hurdle Technology is 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
products.

6. PRINCIPLE OF HURDLE
TECHNOLOGY
 The basic principle of hurdle technology is that preservative factor or
hurdles disturb the homeostasis of microorganism. Microorganisms should
not be able to jump over all the hurdles present in the food product.
 The preservative factors or hurdles prevent microorganisms from
multiplying and causing them to remain inactive or even die.
 The hurdle concept illustrate that complex interactions of temperature,
water activity, pH etc. are significant to the microbial stability.

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9.  Example 1 represents a food containing six hurdles: high temperature
during processing (F value), low temperature during storage (t value),
water activity (aw), acidity (pH), redox potential (Eh), and preservatives
(pres.). The micro-organisms present cannot overcome these hurdles, and
thus the food is microbiologically stable and safe.
 Example 2 Based on hurdles of different intensity. In this particular
product, the main hurdles are aw and preservatives, whereas other less
important
 Example 3 If only a few micro-organisms are present (‘at the start’), a few
or low number of hurdles will be sufficient for the stability of the product .
The super clean or aseptic packaging of perishable foods is based on this
principle.
 Example 4 If due to bad hygienic conditions, too many undesirable micro-
organisms are initially present, even the usual hurdles inherent to a
product may be unable to prevent spoilage or food poisoning.

10.  Example 5 A food rich in nutrients and vitamins, which could foster the
growth of micro-organisms (called the booster or trampoline effect), and
thus the hurdles in such a product must be enhanced, or otherwise be
overcome.
 Example 6 Illustrates the behavior of sub-lethally damaged organisms in
food. For instance, if the bacterial spores in a food are damaged sub-
lethally by heat, the vegetative cells derived from such spores will lack
vitality; therefore, they will be inhibited by fewer or lower hurdles.
 Example 7 In some foods, stability is achieved during processing by a
sequence of hurdles, which are important in different stages of a
fermentation or ripening process and lead to a stable final product. A
sequence of hurdles operates in fermented sausages, and probably in
ripened cheeses or fermented vegetables.
 Example 8 The possible synergistic effect of hurdles, which likely relates to
a multitarget disturbance of the homeostasis of micro-organisms in foods.

11. Potential Hurdles In
Food Preservation…
 HIGH TEMPERATURE (F)
 LOW TEMPERATURE (t)
 REDUCED WATER ACTIVITY (aw)
 INCREASED ACIDITY (pH)
 CONTROLLING THE OXYGEN LEVEL (Eh)
 USING PRESERVATIVES

12. Significance Of Hurdle Tech.
 Improves product quality and microbial safety.
 Saves Money, Energy & Several other Resources.
 Foods remains stable & safe, high in sensory & nutritive value due to
gentle process applied.
 Doesn't affect the integrity of food pieces (fruits).
 Applicable in both Large & Small Industries.
 Manufacture of new products according to the needof processors and
consumers.

13. By- Shubham Soni
College Of Fishery Science, Nagpur.
+91-8237637935

14. A] High Temperature
i) Pasteurization
 It is a mild heat treatment (e.g., 63°C for 30 min; 100°C for 12 sec)
 It increases the product quality.
 Increases shelf-life by destroying the vegetative pathogens (disease-
causing microbes)
 Reduces total microbial load,
 However, it does not destroy spores (dormant stage of some bacteria)
 It is usually combined with other hurdles (e.g., refrigeration)

15. ii) Sterilization
 Aims at Complete destruction of microorganisms
 severe heat treatment (equivalent to several min at 121.1°C)
 destroys the microbes and the spores (C.botulinum gets killed)
 gives "shelf-stable" product
 Disadvantage: some destructions to the nutrients, quality,colour, flavour,
texture etc.

16. iii) Blanching
 Blanching is a kind of pasteurization generally applied to fruits and
vegetables
 Primarily applied to inactivate the natural enzymes that might be present
in the product.
 Also helps to reduce the water activity.
 Commonly practiced when food is to be frozen
 depending on its severity, also destroys the Microbes
*Effect Of Heat On Vegetative Cells
 Vegetative cells are destroyed at temperatures of 60°C to 80°C
 Higher temperature may be needed for killing of thermophilic microorganisms
 Vegetative cells are killed in 10 minutes at 100°C and many spores in 30 minutes at 100°C

17. B] Low Temperature
i) Refrigeration
 It is a short-term preservation method (from days to weeks)
 Ideally temp ranges from 0°C to -4°C for most foods
 It slows down the microbial growth, respiration, enzymatic/chemical
reactions.
 Delivers high product quality (fresh, minimally processed product)
 *Disadvantage
This method cannot destroy Thermophilic Bacteria like C.botulinum

18. ii) Freezing
 long-term preservation (months to years) generally temp ranges from -
18°C to -20°C
 The quality of the product depends on the type of product, preservation
time,temperature.
 slows down the microbial growth, respiration & chemical reactions.
 The product being frozen needs proper packaging.

19. C] Reduced Water Activity (aw)
 Water activity is the available water in the food product which is required
for microbial growth and their metabolic and chemical reactions.
 Free water can be removed by, dehydration and freeze drying techniques.
 In general, the lower the aw the longer the shelf-life of the Product.
** pathogenic microorganisms cannot grow at aw < 0.86
yeast & moulds cannot grow at aw < 0.62
Recommended substances to reduce aw :-
• Glucose
• Fructose
• Sucrose
• NaCl, KCl

20. D] Increased Acidity (lowered pH)
 acidity slows down growth of spoilage organisms and pathogens.
 pathogens won't grow, spores won'tgerminate at pH<4.5
 above pH 4.5, must sterilize for shelf stability.
Recommended Substances to reduce pH:-
• Organic Acid-
• Acetic Acid (Vinegar)
• Citric Acid (Citrus Fruits)
• Malic Acid
• Tartaric Acid (Tamarind)
• Benzoic Acid
• Lactic Acid
• Propionic Acid
• Inorganic Acids etc.

21. E]CONTROLLING THE OXYGEN LEVEL
 Low oxygen inhibits growth of many spoilage organisms
 Using Air Tight Containers, Cans etc
 **Disadvantage
The Anaerobic Bacteria like C. botulinum may survive.
F] PRESERVATIVES
 Chemicals which inhibit the growth of bacteria, yeasts, moulds etc.
 used at low levels (mg/kg) for specific applications
 e.g., benzoate (soft drinks), propionate (bakedgoods), nitrites (meats fish
products), sulfites (wine), ascorbate (juices)

22. Competitive Microorganisms
 "good" bacteria inhibit the actions of "bad bacteria" (spoilers, pathogens).
Termed as Probiotics
These Mainly act by:-
 "crowding out"
 producing acid, lowering the pH thus creating Hostile Environment
 producing antibiotics (bacteriocins)
 e.g., lactic acid bacteria (sauerkraut, yogurt)
Carnobacterium divergens
Lactobacillus acidipiscis , Lactobacillus alimentarius

24. Dry Heat Sterilizer  160°C
** Sterilization
Methods
1.Steam
2.Dry heat
Front Loading Autoclave  121°C- 134°C

25. Salted and Dried FishFishes being Dried in Ratnagiri