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. This article would be throwing light on Hurdle technology for milk products.
As per the definition of hurdle is factor condition, or processing step that limits or retard / prevent microbial growth or reduces the microbial load but which by itself cannot keep microbiological hazard under control. Where hurdle technology is the combination of selected hurdles which keeps microbiological hazard and other micro organism under control with or without the combination of microbiocidal steps so as to obtain and retain the end product safety, sustainability.
|Low Temperature||Chilling and Freezing|
|Reduced water activity||Drying, Curing|
|Increased Acidity||Addition of acid|
In hurdle technology, hurdles are deliberately combined to improve the microbial stability and the referred to the auto-sterilization of stable, hurdle preserved foods. It has been observed that because of elevated temperature, which flavors and probably triggers microbial growth, vegetative cells, strain every possible repair mechanism to overcome the various hurdles present. Thus, because of such autosterilization, hurdle preserved foods that are microbiologically stable become even safer during storage, especially in ambient temperature.
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In the dairy industry, use of thermal pasteurization (TP) is the established food technology for commercial processing of milk. However, degradation of valuable nutrients in milk and its sensory characteristics occurs during TP due to substantial heat exposure. Pulsed electric fields (PEF) and microfiltration (MF) both represent emerging food processing technologies allowing gentle milk preservation at lower temperatures and shorter treatment times for similar, or better, microbial inactivation and shelf stability when applied in a hurdle approach compared to Thermal Processing.
MICROBIOCIDAL HURDLES THAT REDUCE MICROBIOLOGICAL LOAD | Hurdle Technology For Milk Products
The principles of the most common Hurdles within this category are:
- Bactofugation: The removal of microbial cells of high density from milk using high centrifugal forces.
- Competitive microflora: The reduction of the number of undesirable microorganisms by lowering the pH, consumption of nutrients, and production of bacterial antimicrobial substances (such as nisin, other bacteriocins and hydrogen peroxide). Usually, this Hurdle is applied by choice of starter cultures.
- Microfiltration: Removal of microbial cells, clumps and somatic cells by recirculation over a microfilter.
- Ripening (ageing): The holding for such time, at such temperature, and under such conditions as will result in the necessary biochemical and physical changes characterizing the cheese in question. When applied as a Hurdle, the multifactoral, complex system developing in cheese (pH, antagonistic flora, decreased water activity, metabolism of bacteriocins and organic acids) is utilized to influence the microenvironment in and on the food and consequently the composition of the microflora present.
- Thermization: The application to milk of a heat treatment of a lower intensity than pasteurization that aims at reducing the number of microorganisms. Thermized milk is alkaline phosphatase positive.
- High-pressure treatment: Application of high hydrostatic pressures (> 3000 Bar) to irreversibly damage the membranes of vegetative cells.
- Ultrasonication: The application of high intensity ultrasound (18-500 MHz) that cause cycles of compression and expansion as well as cavitation in microbial cells. Implosion of microscopic bubbles generates spots with very high pressures and temperatures able to destroy cells.
- Electromagnetic energy treatment: Electromagnetic energy results from high voltage electrical fields, which alternate their frequency millions of times per second (< 108 MHz). Examples are microwave energy (thermal effect), radio-frequency energy (non-thermal effects) or high electric field pulses (10 – 50 kV/cm, non-thermal effects). The treatment destroys cells by establishing pores in the cell walls due to the build up of electrical charges at the cell membrane.
- Low-intensity irradiation: The submission of beams of photons/electrons to destroy viable microorganisms.
Today public concern is toward minimal damage to food product with maximum protection of food to microorganism. So hurdle technology is the best way by which we can improve both of this characteristic. In dairy industry we can use this technique and improve quality as well as it is possible to make some value added product by this technique.