Hurdle technology is a process by which every preservation parameter is used at an optimum level, in order to achieve maximum microbial inactivation by the amalgamation of two or more such parameters, so that damage to sensory properties of food is kept at a minimum. The process is mainly used for preservation and providing shelf stability to a product by laying hurdles that are difficult to be overcome by microorganisms causing food spoilage. The majority of foods rely on the application of a combination of preservative elements known as hurdles to maintain their microbiological safety and stability as well as their sensory and nutritional quality. Temperature (high or low), acidity (pH), water activity (aw), redox potential (Eh) and preservatives (sorbate, nitrite, & sulfite). Competitive microbes are the main barriers in food preservation (e.g. lactic acid bacteria) (Fig. 1) Singh, S., & Shalini, R. (2016); Tapia, M. S., Alzamora, S. M., & Chirife, J. (2020).
However, more than 60 potential hurdles for foods, which improve the stability / quality of the products. By an intelligent mix of hurdles, this technology aims to improve the total quality of foods. The hurdle technology has enough flexibility, since the hurdles are interchangeable. The application of this technology has to be planned at the stage of designing a food product. A good food technologist should rather than selecting preservation processes, select hurdles, so that a well-balanced combination of the hurdles is applied. The balance should show that even diminutive enhancements to various barriers could result in an overall significant improvement in the microbial stability of food. (De Corato, 2020; Pirozzi, et al. 2021)
It is important to select a proper combination of hurdles, so that an undesirable microorganism is unable to cross them and result in product failure. Products such as fermented sausage require a progressive sequence of hurdles. Hurdles are physical or chemical parameters that can be adjusted to ensure the microbial stability and safety of the foods.
These parameters are controlled at levels that inhibit or inactivate the microorganisms and thus render the food safe. The use of the deterring factors in combination can be advantageous principally by allowing the less extreme use of any single treatment. The hurdle concepts illustrate that complex interactions of hurdles are significant to the microbial stability of foods.
Example of the Hurdle Effect
Self-possessed, these hurdles keep spoilage or pathogenic microorganisms under control, as microorganisms cannot overcome (‘jump over’) all of the sprints present. The following example will illustrate the different cases of preservation of food by selecting six hurdles that are of high temperature during processing (F value), low temperature during storage (t value), water activity (aw), pH, Eh and preservatives Leistner, L., & Gould, G. W. (2002).
Case 1
Some of the microorganisms in the area can get past a few obstacles, but none of them can clear them all at once. Food is therefore steady and secure. Because all obstacles are portrayed as having the same intensity, which is rarely the case in actuality, this scenario is simply a theoretical one.
Case 2
The main obstacles in this situation are water activity and preservatives, whereas minor obstacles include storage temperature, pH and Eh. The typical sorts and numbers of organisms connected with such a product can be inhibited by these five obstacles.
Case 3
Figure (c) illustrates how a few obstacles are enough to ensure the stability of the product, if just a few microbes are present at first. This idea underscores the significant role of aseptic packaging of perishable foods.
Case 4
In this situation, these typical barriers are insufficient to stop food spoiling or food poisoning, if there are too many unwanted microbes present as a result of unsanitary surroundings.
Case 5
In this context, food is nutrient and vitamin-rich, which may permit the rapid proliferation of microbes over a short period of time. Therefore, in this instance, more difficult obstacles are required to ensure product stability.
Case 6
Given this, Microorganisms in food that have been sub-lethally harmed are demonstrated. If meat products contain bacterial species that have been sub-lethally damaged by heat, the vegetable cells formed from these spores (lack vitality), which are therefore already hindered by fewer or lower barriers.
References:
1. De Corato, U. (2020). Improving the shelf-life and quality of fresh and minimally-processed fruits and vegetables for a modern food industry: A comprehensive critical review from the traditional technologies into the most promising advancements. Critical Reviews in Food Science and Nutrition, 60(6), 940-975.
2. Leistner, L., & Gould, G. W. (2002). Hurdle Technologies: Combination Treatments for Food Stability, Safety and Quality: Combination Treatments for Food Stability, Safety, and Quality. Springer Science & Business Media.
3. Pirozzi, A., Pataro, G., Donsì, F., & Ferrari, G. (2021). Edible coating and pulsed light to increase the shelf life of food products. Food Engineering Reviews, 13(3), 544-569.
4. Singh, S., & Shalini, R. (2016). Effect of hurdle technology in food preservation: a review. Critical Reviews in Food Science and Nutrition, 56(4), 641-649.
5. Tapia, M. S., Alzamora, S. M., & Chirife, J. (2020). Effects of water activity (aw) on microbial stability as a hurdle in food preservation. Water activity in foods: Fundamentals and applications, 323-355.
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