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Procesado para la conservación de alimentos

 

Non-thermal preservation technologies use mechanical, electromagnetic, light, or electric energy to inactivate microorganisms. Avoiding modifications generated by heat processing, they generally provide minimally processed foods and beverages with better flavor, freshness while keeping health promoting compounds.  The expansion of those technologies in the industry is driven by customers’ demand for premium, natural (preservative-free), and safe (pathogen-free) products with extended shelf-life. It is noteworthy that High Pressure Processing (HPP) is one of the most accepted non-thermal technologies.


The consumer demand for minimally processed foods has been rapidly increasing. Consumers look for natural and nutritious ingredients, free from additives and excessive heating. This trend is motivated by the consumer’s new consciousness, since the consumer is more and more aware of the effects of excessive heat in food that often damage the ingredients and lead to a sensorial and nutritional loss. Therefore, the food industry has been adapting to this challenge, and in the last years there have been multiples advances in the development of innovative non-thermal preservation techniques.

Among the non-thermal food preservation technologies used, some apply mechanical, electromagnetic, light, or electric energy to inactivate micro-organisms. High pressure processing (HPP), membrane filtration (MF), pulsed electric field (PEF), UV light (UV), and Irradiation are the main ones used commercially at an industry level. Improvement of equipment concerning production capacity and reliability, as well as, better knowledge and understanding of the industry, have facilitated in the last years the adoption of these technologies. However, the penetration in the market of those technologies depends on the countries and the sectors.

What are the main differences between these technologies?

High Pressure Processing

HPP works by submitting the products, already in their final packaging (In-Pack), to pressure levels around 400 – 600 MPa / 58,000 – 87,000 psi during 1-6 minutes, at room or cold temperature. These levels of pressure are effective in the inactivation of yeast and molds, virus, and vegetative bacteria. HPP retains most of the organoleptic and nutritional characteristics of foods, whilst delivers a safe product, minimally processed with extended shelf-life. Traditionally, this technology works In-Pack, however, it is possible to process liquids without being in their final packaging, using Hiperbaric’s Bulk machine, a technology that is exclusive of Hiperbaric.

Pulsed Electric Field

PEF consist of applying an electric current (in short pulses) to foods. It involves placing the food products between two electrodes and applyinghigh voltage (typically 20 to 80 kV/cm) . It can be used for different purposes, among them food preservation. This treatment allows to inactivate microorganisms, however, it can only be used in liquids and semi-solid products. According to Barba et al., there is a synergetic effect between the electric fields and moderate heating promoted by the passage of the electric current.

Membrane Filtration

This method uses a microporous membrane, made of polymeric, ceramic, or metallic materials, that is used to filter microorganisms. As stated by Jeong et al., there are two effects involved, the influence of physicochemical interactions between the membrane and the microorganisms, and the sieving effect, meaning, that the microorganisms that are larger than the size of the pore are retained. Unfortunately, since microorganisms are retained, other biomolecules with important nutritional value can be retained as well.

Irradiation

Irradiation is a processing technique that involves exposing food to ionizing radiation such as electron beams, X-rays, or gamma radiation. The ionizing radiation is capable of penetrating food, guaranteeing food safety without significantly affecting the sensorial or nutritional attributes of food. However is only approved in some countries, and only some ionizing radiation can be used for the treatment of food. Despite this, WHO (World Health Organization), FDA (Food and Drug Administration), and IAEA (International Atomic Energy Agency) have approved food irradiation as safe. FDA obligates producers to inform consumers if the product was processed by Irradiation. This can be done by including in the label the international symbol ‘’Radura’’, and the words ‘’irradiated’’, ‘’treated with ionizing radiation’’, etc.(Figure 1).

Examples of meat products treated with irradiation.
Figure 1. Examples of meat products treated with irradiation.

Ultraviolet Light

UV light produces non-ionizing radiation with germicidal properties at wavelengths in the range of 200–280 nm. It is widely used for surface treatment and can also be used as a non-thermal alternative for fluid foods and ingredients, since it is capable of inactivating microorganisms at these wavelengths.

Please see below a summary table with the main questions answered for each technology.

Comparison of the characteristics of the main non-thermal technologies
Table 1 – Comparison of the characteristics of the main non-thermal technologies. Information adapted from the presentation of Dr. Carole Tonello in IFSH-IFT Workshop – May 25th, 2017.

How consumers accept non-thermal technologies

Non-thermal preservation technologies have attracted the interest and attention of consumers and food manufacturers. It is undeniable that the success of each technology depends on the consumer’s acceptance. They will choose familiar concepts that are easy to understand. Thus, it is essential to educate them in this way, providing the tools for a clear understanding of each technology. Presenting the pros and cons, and clarifying any misconception that might arise.

For example, Suja, Romantics, B Fresh, ColdPress and so many other brands that use HPP, tell a story to the consumer in their product’s label about how the technology works and its benefits. This helps to increase consumer acceptance and awareness. At Hiperbaric we take this commitment very seriously, and try to educate the consumer by continuously releasing updated content on HPP. In 2020 we created a webinar focused on the importance of marketing in the HPP industry.

A study conducted by Khouryieh in 2020 where food experts were interviewed, investigated the perception of some non-thermal technologies in the USA. In this study, HPP was chosen (35.6%) as the most commonly used non-thermal food processing technology, followed by PEF (20%). The results obtained are presented in Figure 2. In this study, more than half of the experts defend that the main factor for choosing these novel technologies is the obtention of better nutrient and sensorial properties in the final product.

Percentage of the non-thermal technologies used by the food industry
Figure 2. Percentage of the non-thermal technologies used by the food industry, adapted from Khouryieh.

Economical evaluation

Some of these technologies require a high initial investment, which can be perceived as a drawback or an obstacle. But there are alternatives, for example, with HPP, there is the option to use the technology through a tolling center. See table below for more information (Table 2).

Summary of the advantages and disadvantages, as well as an estimation of the processing cost per liter of juice of each technology
Table 2. Summary of the advantages and disadvantages, as well as an estimation of the processing cost per liter of juice of each technology. Information adapted from the presentation of Dr. Carole Tonello in IFSH-IFT Workshop – May 25th, 2017.

* Cost calculated for a juice production of about 3000 L/h. As a reference, thermal treatment would cost about 1.5 $ cent/L.

 

If you want more information about how high pressure processing can help you, do not hesitate to contact us.

 

 

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