Hurdle technology

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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. [1]

Contents

Hurdle technology has been defined by Leistner (2000) as an intelligent combination of hurdles which secures the microbial safety and stability as well as the organoleptic and nutritional quality and the economic viability of food products. [2] The organoleptic quality of the food refers to its sensory properties, that is its look, taste, smell and texture.

Examples of hurdles in a food system are high temperature during processing, low temperature during storage, increasing the acidity, lowering the water activity or redox potential, or the presence of preservatives. According to the type of pathogens and how risky they are, the intensity of the hurdles can be adjusted individually to meet consumer preferences in an economical way, without compromising the safety of the product. [1]

Hurdles

Each hurdle aims to eliminate, inactivate or at least inhibit unwanted microorganisms. Common salt or organic acids can be used as hurdles to control microbials in food. Many natural antimicrobials such as nisin, natamycin and other bacteriocins, and essential oils derived from rosemary or thyme, also work well.

Principal hurdles used for food preservation (after Leistner, 1995) [3] [4]
ParameterSymbolApplication
High temperatureFHeating
Low temperatureT Chilling, freezing
Reduced water activity aw Drying, curing, conserving
Increased acidity pH Acid addition or formation (pickling)
Reduced redox potential Eh Removal of oxygen or addition of antioxidants like ascorbate
Biopreservatives Competitive flora such as microbial fermentation
Other preservatives Sorbates, sulfites, nitrites

"Traditionally, fermented seafood products common in Japan, provide a typical example of hurdle technology. Fermentation of sushi employs hurdles that favour growth of desirable bacteria but inhibit the growth of pathogens. The important hurdles in the early stages of fermentation are salt and vinegar. Raw fish is cured in salt (20–30%, w/w) for one month before being desalted and pickled in vinegar. The main target of these hurdles is C. botulinum . Growth of lactic acid bacteria during fermentation results in acid production from metabolism of added sugars and rice. The result is a pH hurdle important in controlling growth of C. botulinum." [1]

Types of hurdles used for food preservation (from Ohlsson and Bengtsson, 2002) [4] [5]
Type of hurdleExamples
Physical Aseptic packaging, electromagnetic energy (microwave, radio frequency, pulsed magnetic fields, high electric fields), high temperatures (blanching, pasteurization, sterilization, evaporation, extrusion, baking, frying), ionizing radiation, low temperature (chilling, freezing), modified atmospheres, packaging films (including active packaging, edible coatings), photodynamic inactivation, ultra-high pressures, ultrasonication, ultraviolet radiation
PhysicochemicalCarbon 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 sulfite, spices and herbs, surface treatment agents
Microbial Antibiotics, bacteriocins, competitive flora, protective cultures

Synergistic effects

There can be significant synergistic effects between hurdles. For example, Gram-positive bacteria include some of the more important spoilage bacteria, such as Clostridium , Bacillus and Listeria . A synergistic enhancement occurs if nisin is used against these bacteria in combination with antioxidants, organic acids or other antimicrobials. Combining antimicrobial hurdles in an intelligent way means other hurdles can be reduced, yet the resulting food can have superior sensory qualities.

See also

Related Research Articles

Food preservation Inhibition of microbial growth in food

Food preservation includes food processing practices which prevent the growth of microorganisms, such as yeasts, and slow the oxidation of fats that cause rancidity. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. By preserving food, food waste can be reduced, which is an important way to decrease production costs and increase the efficiency of food systems, improve food security and nutrition and contribute towards environmental sustainability. For instance, it can reduce the environmental impact of food production.

A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by undesirable chemical changes. In general, preservation is implemented in two modes, chemical and physical. Chemical preservation entails adding chemical compounds to the product. Physical preservation entails processes such as refrigeration or drying. Preservative food additives reduce the risk of foodborne infections, decrease microbial spoilage, and preserve fresh attributes and nutritional quality. Some physical techniques for food preservation include dehydration, UV-C radiation, freeze-drying, and refrigeration. Chemical preservation and physical preservation techniques are sometimes combined.

Salami Cured sausage, fermented and air-dried meat

Salami is a cured sausage consisting of fermented and air-dried meat, typically pork. Historically, salami was popular among Southern, Eastern, and Central European peasants because it can be stored at room temperature for up to 40 days once cut, supplementing a potentially meager or inconsistent supply of fresh meat. Countries and regions across Europe make their own traditional varieties of salami.

Nisin Chemical compound

Nisin is a polycyclic antibacterial peptide produced by the bacterium Lactococcus lactis that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine residues to the didehydro amino acids result in the multiple (5) thioether bridges.

An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals are used against fungi. They can also be classified according to their function. Agents that kill microbes are microbicides, while those that merely inhibit their growth are called bacteriostatic agents. The use of antimicrobial medicines to treat infection is known as antimicrobial chemotherapy, while the use of antimicrobial medicines to prevent infection is known as antimicrobial prophylaxis.

Fermented fish Fish cured by fermentation to reduce spoilage

Fermented fish is a traditional preservation of fish. Before refrigeration, canning and other modern preservation techniques became available, fermenting was an important preservation method. Fish rapidly spoils, or goes rotten, unless some method is applied to stop the bacteria that produce the spoilage. Fermentation is a method which attacks the ability of microbials to spoil fish. It does this by making the fish muscle more acidic; bacteria usually cease multiplying when the pH drops below 4.5.

Pickling Procedure of preserving food in brine or vinegar

Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is called a pickle, or, to prevent ambiguity, prefaced with pickled. Foods that are pickled include vegetables, fruits, meats, fish, dairy and eggs.

A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to be of issue. In fact, depending on perception, these concentrations may impart positive characters to the wine. However, when the concentration of these compounds greatly exceeds the sensory threshold, they replace or obscure the flavors and aromas that the wine should be expressing. Ultimately the quality of the wine is reduced, making it less appealing and sometimes undrinkable.

Lactic acid bacteria Order of bacteria

Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation, giving them the common name lactic acid bacteria (LAB).

Food microbiology Study of the microorganisms that inhibit, create, or contaminate food

Food microbiology is the study of the microorganisms that inhabit, create, or contaminate food. This includes the study of microorganisms causing food spoilage; pathogens that may cause disease ; microbes used to produce fermented foods such as cheese, yogurt, bread, beer, and wine; and microbes with other useful roles, such as producing probiotics.

Fish processing Process from catching to selling fish

The term fish processing refers to the processes associated with fish and fish products between the time fish are caught or harvested, and the time the final product is delivered to the customer. Although the term refers specifically to fish, in practice it is extended to cover any aquatic organisms harvested for commercial purposes, whether caught in wild fisheries or harvested from aquaculture or fish farming.

SCOBY Symbiotic culture of bacteria and yeast

SCOBY is the commonly used acronym for "symbiotic culture of bacteria and yeast", and is formed after the completion of a unique symbiotic fermentation process of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast to form several sour foods and beverages such as kombucha and kimchi. Beer and wine also undergo fermentation with yeast, but the lactic acid bacteria and acetic acid bacteria components unique to SCOBY are usually viewed as a source of spoilage rather than a desired addition. Both LAB and AAB enter on the surface of barley and malt in beer fermentation and grapes in wine fermentation; LAB lower the pH of the beer while AAB take the ethanol produced from the yeast and oxidize it further into vinegar, resulting in a sour taste and smell. AAB are also responsible for the formation of the cellulose SCOBY.

Preserved lemon Type of pickle

Preserved lemon or lemon pickle is a condiment that is common in the cuisines of Indian subcontinent and Morocco. It's also found in 18th-century English cuisine.

Fish preservation

Fish preservation is the method of increasing the shelf life of fish and other fish products by applying the principles of different branches of science in order to keep the fish, after it has landed, in a condition wholesome and fit for human consumption. Ancient methods of preserving fish included drying, salting, pickling and smoking. All of these techniques are still used today but the more modern techniques of freezing and canning have taken on a large importance.

Biopreservation

Biopreservation is the use of natural or controlled microbiota or antimicrobials as a way of preserving food and extending its shelf life. The biopreservation of food, especially utilizing lactic acid bacteria (LAB) that are inhibitory to food spoilage microbes, has been practiced since early ages, at first unconsciously but eventually with an increasingly robust scientific foundation. Beneficial bacteria or the fermentation products produced by these bacteria are used in biopreservation to control spoilage and render pathogens inactive in food. There are a various modes of action through which microorganisms can interfere with the growth of others such as organic acid production, resulting in a reduction of pH and the antimicrobial activity of the un-dissociated acid molecules, a wide variety of small inhibitory molecules including hydrogen peroxide, etc. It is a benign ecological approach which is gaining increasing attention.

Microbial food cultures are live bacteria, yeasts or moulds used in food production. Microbial food cultures carry out the fermentation process in foodstuffs. Used by humans since the Neolithic period fermentation helps to preserve perishable foods and to improve their nutritional and organoleptic qualities. As of 1995, fermented food represented between one quarter and one third of food consumed in Central Europe. More than 260 different species of microbial food culture are identified and described for their beneficial use in fermented food products globally, showing the importance of their use.

<i>Pao cai</i> Pickle in Chinese, and particularly Sichuan cuisine

Pao cai, also romanization as Pao tsai, also known as Chinese pickles, Chinese sauerkraut, or pickled cabbage, is referred to fermented vegetables in Chinese, which typically use different vegetables as raw materials. The different vegetables are then fermented in an anaerobic jar which contains a special pao cai brine. To improve the flavours and create antibacterial effects, garlic, ginger, chilli, onion and cloves can be added during the process of pickle fermentation. In Chinese, pao cai is particularly found in Sichuan cuisine. It is most commonly found in northern and western China; however, there is also a unique form of pao cai, called suan cai, which is prominent in Northeastern China. It is often eaten with congee as a breakfast food. There exists more than 11 types of pao cai in China.

Intermediate moisture food

Intermediate moisture foods (IMF) are shelf-stable products that have water activities of 0.6-0.84, with a moisture content ranging from 15% - 40% and are edible without rehydration. These food products are below the minimum water activity for most bacteria (0.90), but are susceptible to yeast and mold growth. Historically, ancient civilizations would produce IMF using methods such as sun drying, roasting over fire and adding salt to preserve food for winter months or when preparing for travel. Currently, this form of processing is achieved by using one of four methods: partial drying, osmotic drying using a humectant, dry infusion and by formulation. A variety of products are classified as IMF such as dried fruits, sugar added commodities, marshmallows, and pie fillings.

Corn sauce

Corn sauce or fermented corn sauce is produced by fermentation using corn starch as the primary substrate. It is used as a food condiment and ingredient, both in paste and in powder form. Corn sauce, like soy sauce, has a characteristic savory taste. It is used to flavor dishes including soups, broths, and gravies.

Wine preservatives Food preservation

Wine preservatives are used to preserve the quality and shelf life of bottled wine without affecting its taste. Specifically, they are used to prevent oxidation and bacterial spoilage by inhibiting microbial activity.

References

  1. 1 2 3 Alasalvar C (2010) Seafood Quality, Safety and Health Applications John Wiley and Sons, Page 203. ISBN   978-1-4051-8070-2.
  2. Leistner I (2000) "Basic aspects of food preservation by hurdle technology" International Journal of Food Microbiology, 55:181–186.
  3. Leistner L (1995) "Principles and applications of hurdle technology" In Gould GW (Ed.) New Methods of Food Preservation, Springer, pp. 1–21. ISBN   978-0-8342-1341-8.
  4. 1 2 Lee S (2004) "Microbial Safety of Pickled Fruits and Vegetables and Hurdle Technology" Archived 2011-09-01 at the Wayback Machine Internet Journal of Food Safety, 4: 21–32.
  5. Ohlsson T and Bengtsson N (2002) "The hurdle concept" Minimal Processing Technologies in the Food Industry, Woodhead Publishing, pp. 175–195. ISBN   978-1-85573-547-7.