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Hurdle technology
Hurdle technology uses a combination of preservation methods to make foods shelf-stable while maintaining quality and safety. It involves using multiple hurdles like reduced moisture, increased acidity, refrigeration, or addition of preservatives that microorganisms must overcome to grow. The hurdles work synergistically so that microbes cannot adapt to or overcome all of the preservation factors simultaneously. This allows foods to be processed more gently and minimally while still achieving a long shelf life.
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Hurdle technology
- 1. PALLVI DHOTRA ROLL No. 06 FOOD SCIENCE & TECHNOLOGY
- 2. Hurdle technology isthe combined use of several shelf- preservation methods to make a product shelf-stable, to improve quality and to provide additional safety. Also known as “combined method technology”. Leistner in 1976, introduced the term “hurdle effect”. NEED FOR HURDLE TECHNOLOGY Consumers are demanding for fresh, natural and minimally processed food products. Ongoing trend has been eat out and to consume ready to eat foods. New ecology routes for microbial growth have emerged. emerged.
- 3. Preservative factors orhurdles disturb the homeostasis of microorganisms. Microorganisms should not be able to “jump over” all the hurdles present in the food product. Preservative factors prevents microorganisms from multiplying and causing them to remain inactive or even die. The hurdle concept illustrates that complex interactions of temperature, water activity, pH etc are significant to the microbial stability.
- 4. High Temperature i. Pasteurization mild heat treatment (e.g., 63oC for 30 min; 100oC for 12 sec) high product quality destroys vegetative pathogens (disease-causing microbes) (disease- shelf- reduces total microbial load, increases shelf-life does not destroy spores (dormant stage of some bacteria) usually combined with other hurdles (e.g., refrigeration)
- 5. ii. Sterilization completedestruction of microorganisms severe heat treatment (equivalent to several min at 121.1oC) destroys spores gives "shelf-stable" product "shelf- some nutrient, quality destruction (colour, flavour, texture)
- 6. iii. Blanching blanchingis a kind of pasteurization generally applied to fruits and vegetables primarily applied to inactivate natural enzymes commonly practiced when food is to be frozen depending on its severity, also destroys microorganisms
- 7. Vegetative cells, aswell as, viruses are 60° 80° destroyed at temperature 60°C to 80°C Higher temperature may be needed for killing of thermophilic microorganisms Vegetative cells are killed in 10 minutes at 100° 100°C and many spores in 30 minutes at 100°C 100°
- 8. Low Temperature i. Refrigeration ideally 0oC to 4oC for most foods short- short-term preservation (days to weeks) high product quality (fresh, minimally processed, sous vide) slows down microbial growth, respiration, enzyme/chemical reactions some pathogens can grow (e.g., C. botulinum (type E), Listeria)
- 9. ii. Freezing generally-18oC to -30oC quality depends on product, time, temperature long- long-term preservation (months to years) stops microbial growth, respiration slows down chemical reactions must have good packaging
- 10. Reduced Water Activity(aw) aw is water "availability" water is required for microbial growth, enzyme/chemical reactions pathogenic microorganisms cannot grow at aw < 0.86 yeast & moulds cannot grow at aw <0.62 free water can be removed by concentration, dehydration and freeze drying in general, the lower the aw, the longer the storage life
- 11.
- 12. Increased Acidity (loweredpH) acidity slows down growth of spoilage organisms and pathogens pathogens won't grow, spores won't germinate at pH<4.5 (e.g., fruit juices, sauerkraut) above pH 4.5, must sterilize for shelf stability below pH 4.5, can pasteurize
- 13. Organic acids citricacid malic acid tartaric acid benzoic acid lactic acid propionic acid Inorganic acids by- Fermentation by- products
- 14. Controlling Oxygen lowoxygen inhibits growth of many spoilage organisms but: anaerobic conditions required by some pathogens (e.g., C. botulinum) Preservatives inhibit bacteria, yeasts, moulds used at low levels (mg/kg) for specific applications e.g., benzoate (soft drinks), propionate (baked goods), nitrites (meats), sulfites (wine), ascorbate (juices)
- 15. Sulphur dioxide andSulphites Nitrites and Nitrates Sorbates Propionates Sodium benzoate
- 16. Competitive Microorganisms "good"bacteria inhibit "bad" (spoilers, pathogens) May act by: by: "crowding out" producing acid producing antibiotics (bacteriocins) e.g., lactic acid bacteria (sauerkraut, yogurt)
- 17. Sequence of hurdlesensures stability at each stage. All hurdles decline with time except aw. Nitrite inhibits pathogens growth of other bacteria depletes oxygen acid- Low oxygen favours acid-producing competitive flora Acid decreases pH Aw hurdle gradually increases due to drying.
- 18. These products havepH > 4.5 and aw > 0.85. Should have to comply with the low-acid low- canned food regulations (i.e., commercial sterilization). However, for quality reasons, these products cannot be given a sterilization process. Instead, the spreads are stabilized by moderate levels of salt, decreased pH and moisture.
- 19. Improves product qualityand microbial safety. Save Money, Energy & Several other Resources. Foods remains stable & safe, high in sensory & nutritive value due to gentle process applied. Doesn't effects the integrity of food pieces (fruits). Applicable in both Large & Small Industries. Manufacture of new products according to the need of processors and consumers.
- 20. BOOKS- BOOKS- A textbook of food preservation - BY NEELAM KHETARPAL. Food microbiology - BY Food science – BY WEBSITES- WEBSITES- <http://www.ifrn.bbsrc.ac.uk/safety/comicro /Culture_25.pdf> <http://ars.usda.gov/Services/docs.htm?doci d=6786