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Food Preservation Hurdle technology

Research · May 2015 DOI: 10.13140/RG.2.1.2209.4244

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Miguel Costa University of Lincoln

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Abstract

Preservation of evolved throughout the centuries. Recent developments suggest that non-thermal technologies have gained importance. industry is under pressure from consumers to preserve foods in a more natural way, using mild preservation technologies. Preservation of foods is focused on its quality attributes. Hurdle technology looks at every stage of the process and introduces barriers to retain that quality while delivering safe and stable foods. (Heldman 2011)

Describe hurdle technology

Hurdle technology is a combination of methods used in food for the gentle preservation of foods. Previously these combinations were utilized without much knowledge of the governing principles. With the ever expanding these principles of major factors for foods (e.g., temperature, pH, aw, Eh, competitive flora) and their interactions, became more preponderant. Recently, the influence of these preservation methods in in foods are taken into account, and the concept of hurdles in preservation emerged. Hurdles disrupt the homeostasis of microorganisms. With this technology microorganisms should not be able to overcome all the hurdles used for . Preservative factors prevent microorganisms from duplicating and making them stay inert. (Leistner 2000)

Different hurdles and their effectiveness

Microbial safety and stability in foods is based on a combination of preservative factors. Several hurdles can be used to preserve the quality of foods. Temperature high or low, (aw), acidity (pH), redox potential (Eh), chemical (sulphites, nitrites, sorbate) as well as competitive microorganisms are some of the most common hurdles used in food preservation. Various techniques of High and low temperature can be used. Most bacteria are killed at 82-93C, but spores are not. Temperatures of 1210C for 15 min are required to ensure sterility. High acid foods require less heat. is used to eliminate disease causing microorganisms in milk by killing pathogens and substantially reducing the number of spoilage microorganisms. Cold Temperature treatment may kill some microorganisms. Low temperature (refrigeration) retards the growth of microbes but does not stop. Mild heat treatments (pasteurization) are usually combined with refrigeration for the reduction of total microbial load and increase shelf-life. A good example is milk. Water is one of the requirements for microbial growth and enzyme reactions. Reducing water will increase the of food. Pathogenic microorganisms cannot grow at aw < 0.86 and yeast and moulds < 0.62. The use of substances such as sugar for fruits or salt for fish and meat are often used to control microbial growth. Organic acids may be naturally produced by fermentation in foods organic acids can be added artificially. As pH decreases, heat required for sterilization can be reduced. Excluding or providing air is used for control of aerobic microorganisms by the addition of carbon dioxide and nitrogen. This is called or Controlled Atmosphere packaging (MAP). Chemical preservatives (sulphites, nitrites, sorbate) are commonly used in various foods with different levels of usage. Sulphite is used for fruit and vegetables, Nitrite for meats, Sorbate for cheese, juices and wine, Benzoate for pickle food while Citric acid for fruit juice and jams.(NMC-CREES 2014)

Quantitative effects of hurdles

Most common food preservation techniques used are all based on a limited set of factors and their range is limited. They act primarily by slowing down or, in some cases, completely inhibiting microbial growth. Reduction or inhibition of growth can be achieved with different techniques. Low temperature (chill, frozen storage), low water activity (drying, curing), restriction of nutrient availability (emulsions), low oxygen (), raised carbon dioxide (modified atmosphere packaging), acidification (addition of acids) or use of preservatives (sulphites, nitrites) are all used for reduction of microbes. On the other hand inactivation of microorganisms uses heating (pasteurization, sterilization), irradiating (ionizing irradiation), and pressurizing (application of high hydrostatic pressure). (Gould 1996)

Case studies

Listeria monocytogenes is a relatively thermo tolerant pathogen. In an investigation conducted for the reduction of heat resistant in ground beef (ref) the combination of three internal temperatures (57.5, 60, and 62.5 °C) with different concentrations of sodium chloride (NaCl) and apple polyphenols (APP) on the thermo tolerant Listeria monocytogenes was used. The analysis results showed that compared with heat treatment alone, the use of other hurdles (NaCl, APP) decreases the heat resistance of Listeria. The combination of APP and low salt levels (e.g., 2.5% APP and 0.5% salt) suggests salt concentration could be by adding APP to the ground meat. The combined hurdle effects permits a reduction of the temperature for heat treatment as well as the salt levels. The benefits of these combined hurdle technology includes reduction in energy and a reduction on salt levels with benefits for consumer health.(Juneja, Altuntaş et al. 2013) For minimal processing of apples a study was conducted to determine the effect of a combination of hurdles. Temperature, modified atmosphere packaging and anti-browning agents were analysed to determine physical-chemical, sensory, and microbiological parameters of Gala apples stored at 2, 5 or 7C. CO2 and O2 concentrations were monitored for 11 days. Results showed higher weight loss and a reduction in water content at 5 and 7C. The water activity values have decreased on all temperatures. Although was experienced these reductions, the texture, colour or microbiological growth have not suffer significant changes during storage on all temperatures. Apples stored at 2C showed better acceptability. The analysis demonstrated that fresh cut apples shelf life to be 11 or more days. The gas concentration was at equilibrium after 180 h of storage for fresh cut apples stored on all different temperatures. Increases in the CO2 concentrations and decreases in the O2 concentrations were experienced. Fresh-cut apples stored in the same conditions also experience weight loss, texture and reduction of colour. These losses did not influence the acceptance of the product by consumers as demonstrated in their sensory analyses. This study also showed that fresh cut apples microbial counts to be suitable and product to be consumed even on the 11th day of storage.(Fagundes, AMBONI, RENATA DIAS MELLO CASTANHO et al. 2013)

Conclusion

The quality and safety of foods measured by spoilage and poisoning of foods by microorganisms is a growing problem not yet fully under control. A variety of preservation techniques is available such as freezing, , pasteurizing and . A consumer demand for natural and fresh products has urged the food industry as a whole to use only mild preservation techniques such as refrigeration or MAP. Food manufacturers have a need for new and/or improved mild preservation methods to permit the production fresh-like, but stable and safe foods while attending consumer needs. The concept of hurdle technology is not new and is ever increasing in its use in the industry. Interest in design and applications of new hurdle technologies in food preservation is increasing while maintaining healthy, safe, quality food. 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 organoleptic and total quality perceived by the consumer.(Leistner, Gorris 1995).

Reference List

Fagundes, C., AMBONI, RENATA DIAS MELLO CASTANHO and Monteiro, A.R. (2013) Influence of temperature and gas concentration on the physical‐chemical, sensory and microbiological parameters of minimally processed apples (malus xdomestica, b.) cv gala. Journal of and Preservation, 37(5) 405-412.

Gould, G.W. (1996) Methods for preservation and extension of shelf life. International Journal of , 33(1) 51-64.

Heldman, D.R. (2011) [ebook]Food preservation process design / Dennis R. Heldman. Amsterdam London Academic c2011.

Juneja, V.K., Altuntaş, E.G., Ayhan, K., Hwang, C., Sheen, S. and Friedman, M. (2013) Predictive model for the reduction of heat resistance of< i> listeria monocytogenes in ground beef by the combined effect of sodium chloride and apple polyphenols. International Journal of Food Microbiology, 164(1) 54-59.

Leistner, L. (2000) Basic aspects of food preservation by hurdle technology. International Journal of Food Microbiology, 55(1) 181-186.

Leistner, L. and Gorris, L.G. (1995) Food preservation by hurdle technology. Trends in & Technology, 6(2) 41-46.

NMC-CREES (2014) FOOD SPOILAGE AND FOOD PRESERVATION. [online]. Available from http://crees.org/resources/files/forms/29.pdf [Accessed 10/10/2014].

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