“Hurdle Technology” is a technology that uses a combination of two or more preservation parameters at an optimum level in order to get a maximum lethality against micro-organisms without compromising with the nutritional and sensory qualities of food products. A wide range of preservation techniques is available e.g. freezing, blanching, pasteurizing and canning but the spoilage and poisoning of foods by microorganisms is a problem that is not yet under adequate control. Moreover, today’s consumer demands for more natural and fresh-like foods, that requires the use of only mild preservation techniques. Hence, for the benefit of food manufacturers and fulfill the requirement of the consumer, there is a strong need for new or improved mild preservation methods that allow for the production of fresh-like, but stable and safe food.This article would be primarily focussing on Hurdle Technology In Food Preservation
Hurdle Technology In Food Preservation
Types Of Hurdles
There are more than 60 potential hurdles those can be used for food preservation but the most important hurdles used are :
- Temperature(high or low)
- Water Activity (aw)
- Redox Potential (Eh)
- Chemical Preservatives ( Ex-nitrite, sorbate, sulfide)
- Competitive Microorganisms (Ex-lactic acid bacteria)
The preservation of almost all the foods is a result of combined application of several preservative methods (e.g., heating, chilling, drying, curing, conserving, acidification, oxygen-removal, fermenting, adding preservatives, etc.). These methods and their underlying principles (i.e., F, t, aw, pH, Eh, competitive flora, preservatives, etc.) have been applied since long back in our traditional foods empirically, but as the knowledge about these factors has increased, they are being applied intelligently using the concept of hurdle technology. Recently several novel preservative techniques (e.g. gas packaging, biopreservation, bacteriocins, ultra high-pressure treatment, edible coatings, etc.) have gained popularity to be used in combination with other traditional preservative factors(Hurdles).
Every hurdle could have both, positive or a negative effect on foods, depending on its intensity. For example, use of low temperature (chilling) below the critical limit of any food can lead to “chilling injury” whereas moderate chilling will be beneficial for their shelf life extension as it retards microbial growth. Similarly lowering the pH in fermented sausage inhibits the growth of pathogenic bacteria but lowering beyond the required limit can also impair the taste. Therefore a balanced intensity of any hurdle should be used for food preservation. The Too small intensity of hurdle should be strengthened and if it is detrimental to food quality, it should be lowered. This adjustment will provide a food that would be safe as well as will have a good quality by the use of hurdles in an optimal range.
Mechanism Of Food Preservation By Hurdle Technology
The whole mechanism of preservation of food by using the concept of hurdle technology is comprised of various responses those are given by any microorganism. The whole phenomenon can be understood by following:
- Homeostasis: Tendency of any organism to maintain its internal status is known as Homeostasis. The homeostasis of microorganisms plays a key role in food preservation. If any of the hurdles used in food disturbs the homeostasis of these microorganisms, they will not be able to multiply and will remain constant in number or will die before the re-establishment of homeostasis. Therefore, food preservation can be achieved by disturbing the homeostasis of microorganism, temporarily or permanently .
- Metabolic Exhaustion:Another important phenomenon for food preservation is Metabolic Exhaustion of microorganisms. As a response to the hurdles applied to foods, microorganisms try to repair their homeostasis, use up all their energy for this and become metabolically exhausted. This leads to an auto-sterilization of such foods. The foods which are preserved with the concept of hurdle technology and are microbiologically stable, become safer during storage at ambient temperature. The microbes can respond better to the hurdles at ambient temperature than at refrigeration and become metabolically exhausted.
- Stress Reactions: As a response of various hurdles e.g. heat, pH, aw , ethanol, oxidative compounds, etc. as well starvation, a stress shock protein is generated by some bacteria. These stress proteins may hamper food preservation and could turn out to be problematic for the application of hurdle technology if only one hurdle has been applied. If different stresses are received by the microorganism at the same time, the activation of genes for the synthesis of stress shock proteins, which help organisms to cope with stress situation, would be difficult. Synthesis of many stress shock proteins due to simultaneous exposure to different stresses will be very energy-consuming and would lead to metabolic exhaustion of the microorganism.
- Multi-Target Preservation:A combined effect could be achieved by hitting various targets within the microbial cell (e.g., cell membrane, DNA, enzyme systems, pH, aw, Eh) by using different hurdles simultaneously. This disturbs the homeostasis of the microorganisms present in several respects. In this case, the replenishment of homeostasis and activation of stress shock proteins becomes more difficult. Therefore, simultaneous application of different hurdles in a particular food would lead to optimal microbial stability.
The demand of the today’s consumer to enjoy the safe and nutritious food that is much more fresh like can be fulfilled using hurdle technology concept. The hurdles collectively control microbial spoilage and food poisoning leaving desired fermentation processes unaffected. The novel goal for optimal food preservation is the multi-target preservation of foods applying various hurdles those exhibit a synergistic effect. Hence, hurdle technology is used in industrialized as well as in developing countries for the gentle and effective preservation of foods using two or more hurdles to an optimal extent without compromising the sensory quality of the food. Thus, hurdle technology will also be the key to future food preservation.
Here is a visual depiction of the process of HURDLE TECHNOLOGY. See the video below,