HURDLE TECHNOLOGY AN APPROACH TOWARDS FOOD PRESERVATION Divyanshi Mehta1 Somesh Sharma*2 12School of Bioengineering and Food Technology

Divyanshi Mehta1 Somesh Sharma*2
12School of Bioengineering and Food Technology, Shoolini University, Solan Himachal Pradesh India 173229
In the modern era of development, people demand for food with minimum changes in sensory and nutritional attributes, has led to the emergence of hurdle technoloy in the field of food technology. Hurdle technology is a new concept in the preserrvation of foods of plant as well as animal origin. This technology is used in many countries of the world including India. The factors used for food preservation are known as hurdles. A combinational hurdles such as heat, refrigeration, preservatives, irradiation etc. is applied to inhibit or eliminate the growth of microbes, which can either cause spoilage of food or result in food poisoning. Microbial activities account for more than 70% of food spoilage. Presence of active microorganisms in food causes rapid spoilage by directly destroying the nutrients present or by secretion of enzymes that will trigger many chemical reactions that will interfere with the chemical and sensory qualities of the food. It is imperative to use atleast two or three hurdles in the system to control organisms. Each hurdle puts the microorganisms in a hostile environment so that no multiplication can occur in the food, and thereby, extend the shelf life of the food products. It is petinent that right combination of hurdles can ensure the total freedom from microbes and therefore, secure microbial safety, stability, organoleptic, and nutritive quality of the food. Hurdle technology can deleiver the stable and ready to eat meat products to the mountaineers, and space scientists. The multi-targeted preservatin of foods could be an efficient approach in food processing industries. Attempts should be made to develop more hurdles, which can be safely and effectively used to enhance the quality and safety of various foods. It is recommended that hurdle technology may be an important key to food preservation in the future.

Food, Hurdle technology, Microbes, Preservation, Quality, Safety, Microbes
Since the time immemorial, man is dependant on food for survival. A variety of food from plant and animal origin including poultry, egg, fish and sea foods are consumed by humans for growth,health, pleasure and satisfaction besides satisfying nutritional needs Pal et al., 2014. Foods of animal origin are highly perishable. Several foods especially dairy products are susceptible to microbial spoilage due to unhygienic conditions adopted during the manufacturing, handling and packaging. It is estimated that one third of the total harvested foods are spoiled and lost before its is used Pal et al., 2014. Hence, the preservation of food is very important in order to avoid the huge financial lossed occuring due to deteriorative changes bought by microbial, chemical and physical process Pal et al., 2014. The main principle of preservation is to create unfavourable conditions for the growth of microorganisms im food. The conventional preservaton methods are based on single parameter that makes changes in sensory and nutritional quality of the food. However, hurdle technology brings minimum sensory and nutritional changes in the food that caused the product more valuable and acceptable than obtained by conventional ways Pal et al., 2014. Traditionally, fermented sea foods, which are commonly used in Japan, are a good example of hurdle technology.
Hurdle technology is defined as an intelligent combination of hurdles, some of the hurdles such as temperature, water activity, preservatives, competetive microorganisms and acidity. Various novel hurdles that are being applied in various food products includes ultra high pressure, edible coatings, ethanol, mallard reaction products Gayan et al., 2016 The basic cencept is to apply combinations of existing and novel preservation techniques (hurdles) in order to eliminate the growth of microorganisms which secures the microbial safety and stability as well as retains oraganoleptic quality, nutritional benefit, and economic viability of food products.The main theory of bringing hurdle technology up is severity of applying one preserving factor which can lead to degrade nutritional quality as a result of damages may occur to food substances. To have the wholesome foods accompanied and avoid undesirable changes attributed to non-effective methods (destructive methods), multi-hurdle approaches is considered as an appropriate alternative prior to increasing the intensity of a single hurdle factor i.e. combination of hurdles can emerge more synergistic affections, more reduction of pathogens along with more keeping nutrients.The microbial safety and stability of most foods are based on an application of preservation factors called “hurdles” and the techniques applying different hurdles is known as “hurdle technology” Pal et al., 2014. The safety is the attribute of a food, followed by other quality. The shelf life is a period during which a food product maintains its mirobiological safety and suitability at a specified storage temperature.

Food preservation is a process of maintaining the original quality or existing state of food by treatments that will prevent its spoilage or deterioration IFIS et al., 2009. It implies putting microorganisms in a hostile environment in order to cause their death Oladapo et al., 2014. One of the major advances in buman history was the ability to preserve food. It was the prerequisite to man settling down in one place , instead of moving from place to place in the never ending hunt for fresh food. The earliest preservation technologies dveloped were drying, smoking, chilling and heating. Late on the art of controlling these technologies were developed. The work of Pasteur in the nineteenth century made it possible to understand th real mode of operation of preservation techniques such as heating, chilling and freezing, providing the basis for more systematic monitoring and control. The use of various compounds such as salt and spices to npreserve foods was also used in ancient times Peter and Leif et al., 2003. Development for safe, shelf stable foods is necessary t reduce dependnce on refrigeration during their storage and distribution Sujatha et al., 2014
Preservative agents are required to ensure that manufactured foods remain safe and unspoiled. When food is to be stored for a prolonged period, use of preservatives is essential in order to maintain its quality ad flavour. Their use prevents spoilage of fods due to gwoth of bacteria and fungi. They also maintain the quality and consistecy of the foods along with its palatability and wholesomeness. Preservatives also aintain nutritional value, control appropriate pH and enhance flavour Arora et al., 2014. The disturbance of the homeostasis of microorganisms is the main mechanism of dood preservation. Traditional methods for acceptable preservation of foods include heating, chilling, freezing, drying, curing, salting, preservation with sugar, direct, acidifivation, natural fermentation, modified atmosphere packaging and smoking Juneja et al., 2007.

Several objectives of preserving the foods are listed as follow
To ensure the safety of food from microbes
To prevent the spoilage of food
To enhance the keepig qualty of food
To control food borne infectis and intoxifications
To extend the shelf life of food
To reduce the economic losses Arora et al., 2014
According to mode of action, the food preservation techniques can be categorize into three
Slowing down or inhibiting the chemical deterioration and microbial growth
Directly involving the bacteria, yeasts, moulds and enzymes
Avoiding re-contamination of food before and after processing Arora et al., 2014
Most of the current preservation techniques employed for preservation of foods is related to any of these three above mentioned criteria. Great efforts have been done towards preventing the use of a single preservation technique for food preservation to meet the requirement of consumer. However,whn it comes to food safety and shelf life, one has to look for some more complex procedure for prerving the foods Gould et al., 2015. When the preservation fails, the consequences range from minor deterioration, such as colour loss, to food becoming extremely hazardous.

The demand for fresh and good quality food products has led to the emergence of hurdle technology. Several mechanisms are crucial to hurdle technology. There are four mechanisms by which hurdle technology affects the growth of microbes in foods.

Homeostasis is the key phenomenon in food preservation. Homeostasis is the constant tendency of organisms to maintain a stable and balaned internal temerature.The preservative factors functioning as hurdles can disturb the homeostasis mechanism to prevent the microbe from multiplication and making them to remain inactive o evn die Rasoet et al., 2013. The low water activity, low pH and lower redox potential act on food synergistically. The effect of preservation factors (hurdles) on the homeostasis of microbes in various foods may be rewarding.

Metabolic Exhaustion
Hurdle treated stable products have microbes which use their energy for homeostasis, thereby, become metabolically exhausted. This leads to auto-sterilization of food products. Thereafter, microbiologically stable food becomes safe for keeping at ambient temperature Pundir et al., 2015
Stress Reaction
Synthesis of protective stress shock proteins is induced by several factors, such as water activity,pH, heat, ethanol etc. Exposure to multiple stresses can cause the organism metabolically weak. Multitarget preservation of foods can be the key to avoid synthesis of stress shock proteins. Arora et al., 2014.

Multitarget Preservation
The multitarget preservation of food is in which gentle hurdles are intelligently applied which will have synergestic effects. Therefore, application of several hurdles simuntaneously would lead to an optical microbial stability and effective food preservation. It is relevant to mention that multitarget attack of microbes may be a promising approach in food microbiology Singh et al., 2015

An excessive amount of hurdles are employed in many countries of the world to make the food safe to the consumers Pal et al., 2014. Each hurdle aims to eliminate, inactivate or atleast restrain undersirable organisms from the food for good quality and high safety to the consumer. Common salt or organic acids can be used as hurdle to control the microbes in food. Many natural antimicrobials such as nisin, natamycin and other bacteriosins, and essential oils derived from rosemary also work well. Obisson et al., 2013
Physical: All the processes used in food manufacturing come under this hurdle. While using processes intended to kill microorganisms, it is necessary to protect the food product against (microbial) recontamination after processing.

This includes: Ionizing radiation, low temperature (chilling ad freezing), aspectic packaging extrusion,evaporation,pasteurization,sterilization,ultraviolet radiation,electromagnetic energy (radio frequency, high electric fields, pulse magetic fields , microwave), ultrasonification , packaging films , ultra high pressures. Obisson et al., 2013
Physiochemical: Sodium nitrite, Sodium sulphite , potassium sulphite , phosphates , salt , spices and herbs , carbon dioxide , organic acids , surface treatment agents phenols , ethanol , lactic acid , low redox potential , low pH , low water activity , lactoperoxide , smoking , Mailard reaction products. Pundir et al., 2015
Microbial: Bacteriocins , protective cultures , competitive flora , antibiotics
Hurdle is defined as a factor or a processing that limits or prevents the microbial growth and reduce microbial load. Currently, more than 60 Hurrdles are used in food processing industries through out the world. The most important hurdles used as food preservative are nitrate, sulphite and sorbate. Hurdles in a stable product control the microbial spoilage, food poisoning and desired fermentation processes which proves that hurdle effects have fundamnetal importance for the preservation of foods, food poisoning and desired fermentation processes. If the intensity of a particular hurdle in a food is too small, it should be strengthened and in case harmful to the food quality, it should be lowered. Therfore, it is important to mention that hurdles in the food should be kept in optimum range for the safety and quality of the food. Butler et al., 2015
The microorganisms present at the start in a food should not be able to leap over hurdle present during the storage of a product, otherwise food will be spoiled and can even lead to cause food poisoning Pundir et al., 2015, according to the type and severity of pathogens , the intensity of hurdles can be adjusted to meet consumer preference in a economic way without compromising the safety of product. Singh et al., 2016
The hurdle concept describes the fact that complex interactions of temperature, water activity, pH, redox potential etc are important for the microbial stability of foods.
Hurdle allows improvements in the safety and quality as well as the economic properties (i.e. how much water in a product is compatible with its stability) of foods, by an intelligent combination of hurdles. Arora et al., 2014.

In order to grow and multiply, microorganisms need to maintain homeostasis (a stable and balanced internal environment) The combination of best hurdles leads to disturbance of several homeostasis mechanisms occuring simultaneously. This multitargeted approach is more successful than single targeting and allows hurdles of lower intensity.

The following figure shows how work together to limit microbial growth hurdles. It shows several examples of combined processes. By means of dotted lines arrows it clearly shows whether or not the processes are effective in stopping microbial growth.

(Gorris et al., 2015)
Hurdles have impact on the safety and the quality of foods because they have can stop the growth of microbes and at the same time enhance the ?avour of the products. Temperature, water activity, redox potential, preservatives, competitive microoorganisms come under the most significant hurdles used in food preservation. The same hurdle could have a positive or a negative impact on foods, depending on its intensity. For example, chilling to an unsuitable low temperature is harmful to some foods of plant origin (‘chilling injury’), whereas moderate chilling will be bene?cial for their shelf life. Butler et al., 2015
If the intensity of a particular hurdle in a food is too small it should be strengthened, if it is harmful to the food quality it should be lowered. Hurdles in foods can be kept in the optimal range by this settlement considering safety as well as quality. Every stable and safe food require a certain set of hurdles which is different in terms of in quality and intensity depending on the particular product but in any case the hurdles should maintain the population of microorganisms in the food under control. Nida et al., 2015

Aditya et al., 2015
Principle hurdles used in food preservation :
Parameter Application
Low temperature Chilling, Freezing
High temperature Freezing
Reduced water activity Drying,curing,conserving
Increased activity Acid addition or formation
Reduced redox potential Removal of oxygen or addition of ascorbate
Biopreservatives Complete flora such as microbial fermentation
Other Presrrvatives Sorbates,sulfites,nitrates

(Pundiret et al., 2015).

Hurdle technology has been used in a wide variety of foods, such as milk and dairy products, meat and meat products poultry and poultry products, fish and sea foods, canned products, bakery products, juices, jams, pasta, salad, spices etc. in order to increase their shelf life Leistner et al., 2000; Pal et al., 2014.This technology is used in food industry for gentle but effective preservation of food. The sensory and nutritional attributes of foods are maintained in hurdle technology. It is important to mention that application of several hurdles simultaneously would lead to an optimal microbial stability and effective food preservation.

Curd rice, a traditional South Indian dairy product, has shelf life of 24 h at 300°C.The addition of fresh ginger in cured rice as natural preservative, has increased the shelf life to 7 days at 370°C and 12 days at 4 to 60°C.The ginger has been identified as probable hurdle for improved shelf life of curd rice Balasubramanyam et al., 2004. Paneer is an Indian milk product, which remains fresh only for 3 days at refrigerated temperature. However, the application of 1% each of sodium chloride, sucrose and glycerol to decrease the water activity of paneer, increased shelf life of product Rao et al., 1992.Hurdle technology helped to extend shelf life of product for about 30 days at 300°C. Thippeswamy and others (2011) prepared a shelf stable paneer without adversely affecting any of its physio-chemical and sensory properties by applying various hurdles such as pH, aw, preservatives and modified atmosphere packaging (MAP). The product had a shelf life of 12 days at when stored at ambient temperature and twenty days when stored at refrigeration temperature.

Hurdle treated brown peda, a traditional Indian heat desiccated milk khoa product, can be preserved up to 40 days at room temperature without any loss in quality. Panjagri et al., 2007
Several hurdles such as water activity, heat treatment and antimicrobials are applied to preserve high moisture fruit products like papaya, banana, pineapple, mango, and peach (Alzamora et al., 1993).
Hurdle technology can increase the microbial safety of pickled fruits and vegetables. Gamma radiation, osmotic dehydration, and infrared drying can induce the microbial load in pineapple slices and thereby increasing self life up to 40 days (Saxena et al., 2009). Process of hurdle technology is beneficial, as it increases the shelf life of pork sausages. Thomas et al., 2010.

By using several hurdles like irradiation, heat treatment, preservatives, and packaging materials preservation of sugarcane is done and also minimally processed shelf stable high moisture grated papaya using different hurdles like mild heat treatment, aw, pH reduction, and the addition of preservatives is prepared. Hurdle technology was applied in the preservation of fresh scrapped coconut using heat treatment and additives such as humectants, acidulants, and preservatives Gunathilake et al., 2005.
Application of hurdle technology was used to enhance shelf life of chicken lollipop Singh et al., 2014. The efficacy on the use of hurdles such as antimicrobials,partial dehydration,and packaging in polymeric bags to develop grated carrots fresh and microbiologically safe for more than 6 months at ambient temperature was investigated by Vibhakara and others (2016).The experiments conducted by these researchers clearly indicated that the hurdle treated foods have better quality and long shelf life. Thomas et al., 2010.

Using hurdle technology, salamitype fermented sausages are produced that are stable at ambient temperature for extended periods. A sequence of hurdles is important at different stages of the ripening process. The first hurdles used are the preservatives, salt and nitrite, which inhibit many of the bacteria present in the batter. Other bacteria multiply, use up oxygen and thereby cause a drop in redox potential, which inhibits aerobic organisms and favors the selection of lactic-acid bacteria. These bacteria then proliferate, causing product acidification and an increase of the pH hurdle. During the long ripening process of salami, the initial hurdles gradually become weaker: nitrite is depleted, the number of lactic-acid bacteria decreases, redox potential and pH increase. Zhao et al., 2014.

The successful application of these hurdles shows that these can be recommended for preservation of all kinds of food products to enhance the product safety as well as stability. By regulating different hurdles like pH, water activity, proximate composition, FFA, soluble hydroxyproline, TBA values, nitrite content, and protein solubility a shelf stable ready to eat pickle type spiced buffalo meat products was prepared. Malik et al., 2014
Hurdle technology was applied for the production of shelf stable caprine keema using hurdles such as aw, pH vacuum packaging, heat treatment, and preservatives. The hurdle treated keema was shelf stable, and accepted up to the fifth day unlike the conventionally prepared keema that is highly perishable and was found acceptable only for one day. Karthikeyan et al., 2000
As interest in the use of “natural” antimicrobials in food products has increased, so have the sometimes unrealistic expectations of their capabilities in solving food safety and spoilage problems. Thus, the hurdle concept and hurdle technology are central to successful utilization of antimicrobials in food. While use of antimicrobial ingredients to inhibit or reduce populations of spoilage or pathogenic microorganisms in food is a well-known practice, care must be taken not to rely on these substances alone to give the level of safety or quality desired in food products. They are best utilized in the context of hurdle technology, as part of the framework of total microbial control in a food manufacturing facility and/or in food products. hurdles can be applied externally or internally. Many external hurdles (e.g., thermal treatments, non-thermal treatments, sanitation) are designed to inactivate and reduce microbial numbers (cidal effect). Internal hurdles are often designed to inhibit or retard growth of unwanted microorganisms (stasis) by manipulating intrinsic factors such as ph, water activity, or redox potential.
Hurdle technology encompasses the use of interventions to create products with the desired level of safety and quality. The hurdle concept can be applied to the entire production chain, from farm to fork. The beauty of this technology in the creation of food products is that, by understanding the role of each hurdle, the producer can optimize each so that the resultant product is safe, has a long shelf life, and is of the highest possible sensory quality. Use of certain antimicrobial ingredients may make it possible to raise ph or moisture levels or reduce thermal processing times or temperatures and still obtain safe products with superior sensory qualities. Ideally, hurdle systems have components both to kill unwanted microorganisms and to prevent growth of survivors. For example, pasteurization of milk is designed to eliminate pathogenic microorganisms as well as the majority of spoilage microorganisms; subsequent refrigeration is used as an additional hurdle to slow the growth of remaining microorganisms. Extending this example, if the pasteurized milk were to be used as an ingredient in another food, addition of a natural antimicrobial to that food might further retard the growth of the remaining microorganisms in the milk and extend shelf life of the product. Malik et al., 2014

The greatest advantage of hurdle technology is tendency to conquer the ability of microorganisms in developing resistance to conventional preservation methods because in combine technology different preservative acts synergistically by hitting different targets within the cell of the spoilage microorganism. Raso et al., 2011.

Hurdles are use at lower concentrations this prevent the undesired side effects, lower production cost and save energy.

Another advantage is the opportunity of using natural preservatives in combination with synthetic preservatives, this also lower the risk associated with using synthetic preservatives at high concentration. Zhao et al., 2014
Possibility of increasing shelf-stable foods; because food preserved by combined methods (hurdles) remains stable and safe even without refrigeration, and is high in sensory and nutritive value due to the gentle process applied.

This technology leads to the development of high quality food that is shelf stable,wiwth superior quality and ith fresh like characters, further more this approach is not singke targeted but multi targeted. Abdullahi et al., 2016
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 betwween hurdle technoogy is used for food design , the HACCP concept ( used for process control) and predictive microbiology( used for process refinemnt and food safety) is absolutely necessary. Velugoti et al., 2011
The demand for processed food has increased in recent times due to rapidly growing economy. Moreover, consumers nowdays have demands for fresh, natural and minimal processed ready to eat food products.The most important hurdles used are food preservatives and competitive microorganisms. Pundir et al., 2015.

In hurdle technology, hurdles are intentionally combined to improve the microbial stability and the sensory as well as their nutritional quality of foods and economic properties. The phenomenon of homeostasis is the constant tendency of microorganisms to maintain a stable and balanced internal environment is crucial to hurdle technology.Food preservation is achieved by disturbing the homeostasis of microorganisms. The best way to do this is to intentionally disturb several homeostasis mechanisms at the same time Raso et al., 2011.
Autosterilization of hurdle preserved foods that are microbiologically stable become even more safer during storage especially at ambient temperature . It is noticed that raised temperature which favours and probably triggers microbial growth, vegetative cells strain every possible repair mechanism to overcome the various hurdles present. Gorris et al., 2005. Presently, the most important need for is to develop the new methods so as to produce stable and safe food as demanded by the consumers. Pundir et al., 2015.

Food plays a key role in our life, as it is the major source of energy to perform various activities. Hurdle technology was developed to address the consumer demand for more natural and fresh foods. The application of hurdle technology is useful for the optimization of traditional foods as well as in the development of novel products. The importance and potential of this technology in better food preservations been recognized in developed as well as in developing nations of the world.There are several hurdles such as reduced water activity, reduced redox potential, high and low temperature, preservatives, and competitive flora. A combination of selected hurdles can keep microbiological hazards under control in order to obtain and retain the end product safety and suitability. The combination of hurdles in food preservation is primarily to process food while obtaining safe foods that are microbiological safe using mild techniques. However the hurdle technology could also contribute for an improved consumer experience in respect to or Hurdle technology is an important approach that can be used to improve quality parameters during processing and storage of food. Smart application of hurdles improves sensory characteristics, chemical and microbiological qualities of food. More than 60 hurdles reported to be available; these can be use in different combinations and concentrations in wide range of foods. This versatility makes the application of the technology possible in both modern and local food processing.
Today public concern is toward minimal damage to food product with maximum protection of food to microorganism. So any one preservation technique lead to damage to nutritional value or sensory damage. So hurdle technology is the best way by which we can improve both of these characteristic. With the growing economy there is an increased demand for fresh and minimally processed food products. Conventional fruit preservation methods are based on single preservation parameter that makes changes in the sensory and nutritional quality of the fruit. The hurdle technology makes minimal sensory and nutritional changes in the product which makes the product more valuable and acceptable than obtained by conventional methods and has become a boon for the efficient preservation of food products.

Hurdle technology improves the total quality of food by application of an intelligent mix of hurdles.This technology has been applied on various types of foods originating from animal as well as plant origin. Hence, hurdle technology has become a boon for efficient preservation of food products. It is emphasized that this technology must be widely used in order to get high quality of safe and stable food for the consumers. Further research on the response of microorganisms to homeostasis, metabolic exhaustion, and stress reaction in relation to hurdle technology should be conducted.

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