Hurdle Technology for Preservation of Food
Author: Palshikar L. S.

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 in food is defined as the substance or the processing step or various preservation factors, inhibiting the growth of various microorganisms resulting in the death of microorganisms. 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. It promotes the deliberate combination of existing and novel preservation techniques in order to establish a series hurdle that any microorganisms present should not be able to overcome, therefore bacteria will not multiply. They will remain in lag phase or will die.

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 products.

"Traditionally, 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.

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.

Potential hurdles for use in preservation of food

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

Sr. No. Hurdle Example
1 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 (including active packaging , edible coatings), photodynamic inactivation, ultra-high pressures , ultrasonication, ultraviolet radiation
2 Physico-chemical hurdles 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 sulphite, spices and herbs, surface treatment agents, glucono-o-lactone, lactoperoxidase and lysozyme.
3 Microbially derived hurdles: Competitive flora, protective cultures, bacteriocins and antibiotics


Advantages of Hurdle Technology:

The technology leads to the development of high quality food that is shelf stable, with superior quality and with fresh like characters, further more this approach is not single-targeted but multi-targeted. There is every possibility that different hurdles will have an additive or synergistic effect in food. The concept of hurdle technology has proved extensively useful in optimization of traditional foods as well as development of novel products. For securing stable, safe and tasty foods, linkage between hurdle technology (used for food design), the HACCP concept (used for process control) and predictive microbiology (used for process refinement and food safety) is absolutely necessary.

Several methods such as freezing, canning, dehydration, chemical preservation etc. are commonly used for preserving foods. However, all these processes are based on a relatively few parameters or 'hurdles', combination of which decisively govern microbial stability and nutritional quality of almost all foods.

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.

References:

1. Principles of Food Processing Dr Shruti Sethi Scientist Division of Post Harvest
Technology, IARI
2. https://en.wikipedia.org/wiki/Hurdle_technology


About Author / Additional Info:
I am currently working as Assistant Professor at K. K. Wagh College of Agricultural Biotechnology, Nashik