Future Prospectus and Application of Hurdle Technology in Livestock Industry
Anita Chappalwar1, Meera sakhare2
1Assistant Professor, Department of Livestock Products Technology,
2 Assistant Professor, Department of Veterinary Medicine
College of Veterinary and Animal Sciences , Parbhani-431402, Maharashatra, India
*Corresponding Author: Anita Chappalwar1, Assistant Professor, Department of
Livestock Products Technology College of
Veterinary and Animal Sciences, Parbhani-431402, Maharashatra, India
Abstract
Animal origin foods viz, milk and milk products, poultry, egg, fish and sea foods are universally nutrient rich prone to bacterial spoilage Hurdle technology is a new concept includes existing and new preservation techniques to establish a series of preservative factors that provides the microbial safety, shelf stability as well as retains the organoleptic, nutritional quality and economic viability of food products. Hurdle technology usually works by combining more than one approach. The microbial stability and safety of the most traditional and novel foods is based on combinations of several preservation factors (called hurdles) and the microorganisms present in food are unable to overcome.
Keywords: Hurdle Technology, Livestock Products, High pressure processing, Ozonization,
Microbial metabolites
Introduction
Food is an essential element for survival of every living adventure on earth, who consumes a diversity of plant and animal origin foods for nutritional needs as well as satisfaction (Pal. 2014). However animal origin foods viz, milk and milk products, poultry, egg, fish and sea foods mostly liked by human being due to its unique taste and nutritive value. High nutritional content of animal origin food contribute to the microbial growth ensuing spoilage and food poisoning., Major causes of food spoilage are growth of Bacteria, yeast and mould, reaction with light and oxygen, improper storage temperatures and time, improper ventilation, humidity, excessive delay between receiving and storing, inadequate food safety standards, predominant food spoilage is due to the growth of micro-organisms. However the microbial stability and safety of the most traditional and novel foods is based on combinations of several preservation factors (called hurdles), and the microorganisms present in food are unable to overcome.
Hurdle is a factor, a condition or a processing step that limits, retards or prevents or reduce the microbial load. Hurdle technology was introduced several years ago as a concept to ensure food safety and stability that can eradicate/control food pathogens. Hurdle technology usually works by combining more than one approach. This technology comprise combination of existing and new preservation method to extend shelf life of product by reducing hazards, that can achieve multi-target, mild but reliable preservation effects. Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles which secures the microbial safety and stability as well as retains the organoleptic, nutritional quality and economic viability of food products.
Hurdle technology generally involves use of sub-inhibitory level of several hurdles. Thus addition of substance at concentrations where it itself does not give full inhibition can effectively preserve products in presence of other sub-inhibitory limiting factors. Combination treatments are applied because it is expected that the use of combined preservative factors will have greater effectiveness at inactivating microorganisms than the use of any single factor. It is of paramount importance in developing countries due to lack of storage facilities hence, now a days more or less used many food industry as a new concept for the production of safe, stable, nutritious, tasty and economical foods (Leistner and Gorris, 1995).
Basic Principles of Hurdle Technology
The most important hurdles viz., temperature (high or low), water activity (aw), acidity (pH), redox potential (Eh), preservatives (e.g., nitrite, sorbate, sulfite), and competitive microorganisms (e.g., lactic acid bacteria) employed for food safety. Deliberate and intelligent application of hurdle technology allows gentle and efficient preservation of foods, which is advancing worldwide. A better understanding of the impact and interaction of different preservative factors (hurdles) in food is the basis for improvements in food preservation, because if the hurdles in a food are known and their interactions are visualized, the microbial stability and safety of this food might be optimized by changing the intensity and quality of these hurdles. Understanding the hurdle effect is the key to understand the effectiveness of traditional preservation of food products. In order to determine the food stability, two questions need to be asked: what target attribute(s) needs to be achieved in the microbial, chemical, bio-chemical and physical changes; and what is the required time frame of stability? The critical limits are being used by the industry when each hurdle such as heat treatment, water content, pH and storage temperature is applied alone. Fundamental based theoretical concepts of F-value (hurdle: heat treatment), water activity (hurdle: water content) and glass transition (hurdle: glassy state; depending on water, storage temperature, and structure) are the most successful in determining food stability during food processing and storage. In achieving the desired safety by only one hurdle, high severity in processing needs to be applied. This may cause significant damages to the nutritional and sensory quality of foods. For this reason, it is important to have multi-hurdles approach for developing safe and wholesome food products.
Principal hurdles used for food preservation (Leistner, 1995)
| Parameter | Symbol | Application |
| High temperature | F | Heating |
| Low temperature | T | Chilling, freezing |
| Reduced water activity | aw | Drying, curing, conserving |
| Increased acidity | pH | Acid addition or formation |
| Reduced redox potential | Eh | Removal of oxygen or addition of ascorbate |
| Biopreservatives | Competitive flora such as microbial fermentation | |
| Other preservatives | Sorbates, sulfites, nitrites |
OBJECTIVES OF HURDLE TECHNOLOGY
- To employs the intelligent combination of different hurdles or preservative techniques to achieve multi- target preservation effects.
- To enhance product safety and stability.
- To increase the shelf life of product at ambient temperature.
Table 1. Impending hurdles in food
| Physical hurdles | Aseptic packaging, electromagnetic energy, high temperatures, blanching, pasteurization, sterilization, evaporation, extrusion, Ionic radiation, low temperature (chilling freezing), modified atmospheres, packaging Films (including active packaging, edible coatings), photodynamic inactivation, ultra-high pressures, Ultrasonication, ultraviolet radiation. |
| 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 |
| Microbially derived hurdles | Antibiotics, bacteriocins, competitive flora, protective cultures |
(Ohlsson and bengtsson, 2002)
Application of hurdle technology
An important phenomenon that is crucial to hurdle technology is homeostasis of microorganisms. Homeostasis is the constant tendency of microorganisms to maintain a stable and balanced (uniform) internal environment. Initially it was used for the gentle preservation of mildly heated, fresh like meats storable without refrigeration (Saggar, 2010). Preservative factors function as hurdles can disturb one or more of the homeostasis mechanisms, thereby preventing microorganisms from multiplying and causing them to remain inactive or even die. Another phenomenon is referred to the auto-sterilization of stable, hurdle preserved foods. It has been observed that because of elevated temperature which favours 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 at ambient temperature. Packaging is an important hurdle for most foods, since it supports the microbial stability and safety as well as the sensory quality of food products. Developed countries have the tendency to overpackage foods at industrial level, where “active” packaging (using scavengers, absorbers, emmiters, antimicrobial or antioxidative packaging materials, etc.) has been developed to perfection. More recent is the application of traditional hurdle technology for microbial stabilization of novel healthful foods derived from meat, poultry, or fish, which contain less fat and/or salt and therefore are more prone to spoil or cause food poisoning.
Hurdle Technology in dairy products
In 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.
Geetha (2005) extended the shelf life of Gasasase (poppy seeds) payasum, a product prepared from poppy seeds and rice by application of retort processing (f0 value 6 at steam pressure of 1.04 bar) to 6 weeks at 37°C temperature with marginal change in pH, acidity, HMF content and viscosity. Sachdeva and Singh (1990) made an attempt to enhance the shelf life of paneer with application of hurdle technology and observed that dipping of paneer in 5% brine, acidified brine (5%NaCl, pH 5.5) and hydrogen peroxide solution (0.2%, v/v) with or without delvocid (0.5%, w/v) extended the shelf life of paneer cubes of small size (1.0 × 0.25 × 0.5 inches) to 22, 20, 32 and 22 days respectively compared to 10 days for control at 8–10°C.
Nisin has been shown to enhance the microbial reduction achieved by HP, due to sub-lethal injury and sensitization caused to target cells. Studies carried out on milk demonstrated that Gram negative bacteria, such as Pseudomonas fluorescens or Escherichia coli and Gram positive bacteria, as L. innocua, are inactivated by HP treatment, although Gram – positive bacteria seemed to be rather resistant (Black et al., 2005).
Shelf stable paneer can be prepared by applying various hurdles such as pH, aw, preservatives and Modified Atmosphere Packaging (MAP) (Thippeswamy et al., 2011). In another study, the shelf life of paneer curry was increased using hurdle technology. The product was treated with certain modified control hurdles like aw, pH and preservatives. The hurdle treated paneer was found to have better quality than heat sterilized product (Rao and Patil, 1999). Another product brown peda, a traditional Indian heat desiccated milk khoa based product have also been prepared and preserved through hurdle technology.
Panjagari et al. (2007) studied the effect of conventional cardboard boxes, modified packaging and vacuum packaging techniques on the sensory, physico-chemical, biochemical, textural and microbiological characteristics of brown peda during its storage for forty days at 30ºC and observed a stable shelf life due to low moisture content, higher amount of sugar and severe heat treatment applied during its preparation. Hurdle treated brown peda could be best preserved up to forty days at room temperature (30±1ºC) without any quality loss .
The principles of the most common Hurdles use to reduce microbial loads in milk and milk products are: Bactofugation, Competitive microflora, Microfiltration: Ripening (ageing), Thermization, Ultrasonication, Electromagnetic energy treatment and Low-intensity irradiation.
Hurdle Technology in meat products
Positive hurdles, which keep the membrane lipids in apparently unchanged physiological condition and thus prolong the shelf-life of foods, are: relatively low temperature, appropriate relative humidity, absence of light and slight anoxia.
Thomas et al (2008) reported that hurdles incorporation like low pH, low water activity (TSP) and vacuum packaging and preservative (potassium sorbate) into sausages were effective in development of shelf stable pork sausages. Salt, sodium nitrite, dehydration, and packaging are hurdles sequentially applied to inhibit deteriorating microorganisms with the possibility of selecting desirable microbiota. Shelf stable pork sausages were developed by Thomas et al. (2008) using hurdle technology and their quality was evaluated during ambient temperature (37±10C) storage. Hurdles incorporated were low pH, low water activity, vacuum packaging and post package reheating.
Karthikeyan, (2000) developed Chevon (capine) keema, through the application of hurdle technology. The hurdles used were water activity (aw) and pH as variable hurdles as well as vacuum packaging, preservatives and heat treatment as constant hurdles. Lara et al., (2003) prepared Charqui meats to observe the possibility of development of enterotoxigenic Staphylococcus aureus and Clostridium botulinum proteolytic type B spores and their toxins. Chawla, (2004) developed shelf stable meat products by using a combination of hurdles (irradiation, reduced water activity, and vacuum packing) to test the effectiveness of these hurdles in preventing the growth of Clostridium sporogenes. The studies demonstrated that a combination of the above hurdles results in microbiologically safe and shelf-stable meat products. Leistner (1994) developed Lup Cheong (raw nonfermented sausage of China storable for several weeks without refrigeration) by the addition of 3.5% sodium lactate and 0.1% sodium acetate. Furthermore, a better understanding of the sequence of hurdles that leads to microbial stability of sweet and sour chicken meat spread/jam using multiple hurdle technology was done to improve the safety and quality of meat jam (Arya, 2017).
Recent novel techniques used in hurdle concept
Currently, consumers are more interested in minimally processed food products without additives, improved safety and shelf life. Owing to these facts, the hurdle concept has become a promising technology that simultaneously reduces losses of nutritional and sensory quality and improves food safety (Rahman, 2015). Knowledge of the basic aspects related to hurdle technology (i.e. homeostasis, metabolic exhaustion, and stress reactions of micro-organisms) has also advanced in recent years. This has paved the way for the application of multi target preservation of foods, which is the ambitious goal of the future in food preservation.
At present, physical, non-thermal processes (high hydrostatic pressure, oscillating magnetic fields, pulsed electric fields, light pulses, etc.) receive considerable attention (Nonthermal Processing), since in combination with other conventional hurdles they are of potential use for the microbial stabilization of fresh-like food products, with little degeneration of nutritional and sensory properties.
Radio frequency (RF) and microwave (MW) heating
Various decontamination techniques have been developed over last decade from external heating sources to ohmic heating and microwaves. Dielectric heating (DEH) promises rapid and uniform heating patterns in foods, and ensures the safety and quality of food products DEH implies the interaction of ionic charges and dipoles contained within the food product with electromagnetic alternating fields that enable volumetric heating of the product (Pereira and Vicente, 2010). MW and RF are dielectric heating technologies controlled by the same principles that allow for rapid and uniform heating throughout a medium (Piyasena et al., 2003).
Irradiation and sterilization
Food Irradiation is a process in which food products are exposed to ionizing radiation in form of gamma radiation, X-rays and electron beams in controlled amount to destroy pathogenic microorganisms in order to increase its safety and shelf life (WHO, 1991). Ionizing radiation has enough energy to remove electrons from atoms and leads to ions formation. Ionizing radiation comes in different forms depending on the source (X-ray, gamma rays, and beta rays), however, all forms exert their effects by “stripping” electrons from atoms. This irradiation causes breaks in the DNA and/or RNA helix and leads to the disruption of normal cellular functions by damaging nucleic acids by either direct or indirect effects (Kuan et al., 2013). Irradiation can effect directly, caused by reactive oxygen-centred (ïOH) radicals originating from the radiolysis of water or indirectly on organisms and food products. An indirect effect (the damage to the nucleic acids) occurs when radiation ionizes a neighboring molecule, which in turn reacts with the genetic material. Since, water is a major component of most foods and microbes; it is often ends up producing a lethal product (Hallman, 2001).
High pressure processing
High pressure processing is a novel non thermal technique that emerged in food processing for improving shelf life and safety of various food products by means of microbial inactivation. It is also known as ultrahigh-pressure processing or high-hydrostatic pressure processing. For food applications, the minimum and maximum limits of HPP are 200 MPa and 600 MPa, respectively (Wadpalliwar et al. 2016) The reductions in food size are proportional to the amount of pressure applied; however, the food retains its original shape. The effect of HPP processing on chemical and microbial changes in food is governed by Le Chatelier’s law.
Ozone treatment/Ozonization
Ozone (O3) is an allotropic form of oxygen that is produced naturally from oxygen during lightning or UV irradiation reactions (Cesar et al., 2012). Ozone can be produced using UV light or corona discharge generators. During ozone generation, O2 splits into highly reactive free radicals, which in turn react with other oxygen molecules to form ozone. Ozone is an effective antimicrobial and potent antioxidant agent. Ozone acts by two different mechanisms to destroy bacteria. During the first mechanism, ozone oxidizes enzyme amino acids, sulfhydryl groups, proteins and peptides; during the second mechanism ozone oxidizes polyunsaturated fatty acids to acids and peroxides (Sharon et al., 2013). The advantages associated with ozone treatment are decomposition of triatomic allotrope to oxygen automatically and rapidly, leaving no residue in the food products.
Ohmic heating
Ohmic heating is a food processing operation in which heat is internally generated within foods by the passage of alternating electric current. Ohmic heating or Joule heating has immense potential for achieving rapid and uniform heating in foods, providing microbiologically safe and high quality foods (Varghese et al., et al., 2013). The applicability of ohmic heating is dependent on electrical conductivity of the product. The electrical conductivity of foods affects with temperature, applied voltage, concentration of the electrolytes, food particle size and type of pre-treatment. It can be used as a continuous in-line heater for cooking and sterilization of viscous liquids and mixtures containing particulate food products.
Microbial metabolites
Lee and Paik (2016) reported that various treatments are used since immemorial to prevent spoilage of food including animal derived systems (lysozymes, lactoferrin and magainins), plant derived (phyoalexins, herbs and spices) and microbial metabolites (bacteriocins, hydrogen peroxide, organic acids). Nisin and natamysin are commonly used food grade antibiotics of microbial metabolites origin (Kallinteri et al., 2013). Bacteriocins are proteinous antibacterial compounds that constitute a heterogeneous sub group of ribosomally synthesized antimicrobial peptides and that are commonly produced by different spices of lactic acid bacteria (Ramith 2017).
Future opportunities of hurdle technology
- Hurdle technology used in correct way is a good tool for achieving safe and sensory rich products of high quality.
- It conquers the tendency of micro organisms to develop resistance to conventional preservation systems
- Opportunities to use natural preservation in combination with synthetic preservatives so as the products become more natural thereby creating an overall healthier, less synthetic final product.
- In India there is big problem of electric -interruption so there will be increasing demand for Hurdle Treated Foods (HTFs) in future due to awareness among people.
- It is an advanced technology gives synergistic effects for combinations of different preservative methods for preservation of food which is highly perishable in nature .
Conclusion
- Present day consumer is conscious toward minimal damage to food product with maximum protection of food to microorganism.
- Various traditional and novel hurdles are available which can be used in different combinations and concentrations to have synergistic effect on food preservation.
- The combination of two or more scaffold techniques reduces the cost of decontamination, minimizes the effects of treatments on food products and most of all extends the shelf life.
- The versatility makes the application of hurdle technology possible in both traditional and modern food processing.
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