a technology to improve food safety

Innovation in processing is one of the fundamental pillars of increasing efficiency and profitability in the food industry. Among the technologies researched in recent years, CO₂ Lasers have the incredible ability to transform the future of food production.

The laser’s temporal and spatial precision allows laser energy to be focused into a small spot and follow complex patterns without overly affecting nearby food materials.

Food Safety Culture: What Is It and How Do We Measure It?

This is especially important for some mechanical and thermal processes. For example, it has been proposed to inactivate microorganisms on food contact surfaces. It can also be used for non-contact cutting, avoiding the physical, chemical and microbiological cross-contamination problems of other systems such as blades and waterjets. Or food marking, paper/plastic labels and ink replacement.

CO₂ Lasers: main properties and effects on food

A laser (an acronym for light amplification by stimulated emission) consists of an energy delivery system that excites the molecules of the gain medium to produce light.

This light is amplified in an optical cavity confined by two mirrors. One of each mirror is partially transparent, allowing a coherent, directional laser beam to pass through. This laser beam can be focused onto the target material with temporal and spatial precision by a software-controlled lens system.

carbon dioxide (CO₂) laser uses CO, hence its name.₂ As the main component of the gain medium, it emits a laser beam at mid-infrared wavelengths (typically 10,600 nm).

Infrared wavelengths are transmitted through the atmosphere with little loss. Furthermore, it is efficiently absorbed by water, which is the main component of food. Both are therefore likely to be the main reason for CO interest.₂ Lasers are used in food processing.

By modulating the radiant energy of CO₂ Laser light, photochemical, thermal, and mechanical effects are gradually produced in food.¹ For CO₂ The laser energy is low and the laser only disturbs the bonds between atoms and molecules. At higher radiant energies, the laser beam energy is converted into thermal energy, heating the food surface (a few millimeters deep) in a precise and controlled manner.

By further increasing the radiant energy, a direct mechanical effect can be produced on the food surface, eventually forming craters based on vaporization and ablation phenomena.¹

The ablation process can be repeated on the lower layers of food, allowing food to penetrate deeper or continue in adjacent zones, following a specific pattern. Based on these effects, CO₂ Lasers can be used for a wide range of food applications including decontamination of microorganisms, cooking, marking and cutting.

Microbial decontamination

CO₂ Lasers are a non-contact, relatively fast inactivation technology for microorganisms on the surface of various substrates, and are an alternative to traditional surface cleaning and disinfection systems such as the use of chemicals. .

For food contact surfaces (e.g. cutters, conveyor belts) heating is less of an issue and laser accuracy and processing speed play an important role. for example, Escherichia coli When Staphylococcus aureus has been reported on stainless steel surfaces after CO₂ Laser treatment (660 W; 0.8-1.3 cm/s).² Apart from microbial inactivation, the mechanical effects of CO₂ Lasers can also help remove hard-to-clean organics and biofilms from these types of surfaces.

CO₂ Lasers can also inactivate microorganisms present on the surface of food.³ However, in this case the treatment has to be highly optimized to minimize the effects on surface properties, avoid mechanical effects and minimize thermal effects.

Despite optimization, surface changes such as color changes are usually detected. Using flavonoids, riboflavin, or other antioxidants can reduce or even avoid these negative effects.^Four

Heat treatment

CO₂ Lasers can be used as an alternative to traditional thermal technology for cooking, grilling and browning, utilizing the high energy of the light beam.^4-5

However, in this case, the charring and ablation processes (thermal and mechanical effects, respectively) associated with high energy intensity treatments should be avoided.

in food cooked with CO₂ laser, microbial reduction salmonella typhimurium, salmonella Senftenberg and Escherichia coli O157:H7 is observed similar to that obtained with common cooking methods such as infrared ovens, electric barbecues, and electric flat grills.³ For CO₂ Although the treatment is adjusted to reduce charring, laser-cooked foods also exhibit the same amount of polycyclic aromatic hydrocarbons as conventionally cooked foods.³

CO precision₂ Lasers mean that only one portion of food (e.g. just the fat part of bacon) or each portion of food can be cooked under optimal conditions (temperature, time), changing the treatment energy on the fly and increasing the exposure time.^Five In this context, CO₂ Lasers have received special attention in 3D printing of food where precise heat transfer is required to cook pre-printed food.^Five

The authors state that the accuracy of CO is₂ Laser means you can only cook a portion of your food, such as the fat part of your bacon.

Laser energy penetrates only a few millimeters into food and is therefore suggested for cooking thin foods and surface treatments such as grilling and browning. Many products use lasers for surface finishing (such as grill marks) and are proposed to be used in combination with other technologies such as microwaves.³

food marking

The use of lasers for marking fruits and vegetables is licensed and practiced in industry in several European countries. They have been tested on a variety of food products including fruits, vegetables, eggs, meat, cheese, chocolate and cereal products (Figure 1).

Figure 1: QR code marking on cheese with a CO2 laser (example of laser processing).

What makes it interesting is the fact that it doesn’t require plastic/paper labels or adhesives and is made to avoid contact. From a general point of view, CO₂ Lasers can be used for marking based on mechanical effects (engraving) or thermal effects (Maillard reaction).

In both cases, the laser can be operated according to almost any pattern, thus marking numbers (e.g. expiry date, batch number), letters (e.g. origin, company name) and codes (e.g. barcode, QR) . Or complex drawings and designs (quality labels, company logos, etc.).⁶

Mechanical food processing: cutting, peeling, perforating

Using the ablation phenomenon, CO₂ Lasers can be used as a non-contact technique for cutting and peeling, or for other mechanical procedures such as perforation that can be used in some operations such as marinating and compound extraction.^1,4

advantage

CO₂ Lasers have several advantages over traditional techniques that use blades, knives, needles, or similar devices.

First, the working area is partially decontaminated (deactivation of microorganisms) by the action of the laser beam.

It is also possible to process food according to complex patterns that are difficult or even impossible with conventional technology.

Finally, pattern changes can be made on the fly without the need to stop the line to clean the mechanical cutting elements. In conventional technology, changing the cleaning process or cutting configuration involves stopping the line to clean, change, replace, or move cutting elements.

Limitations

Most important restrictions on CO use₂ Lasers in this kind of mechanical process are heat generated and relatively shallow depth of cut.

Effective selection of laser processing parameters is critical to avoiding burnt edges on food and achieving good performance. For depths greater than a few millimeters, several laser processing cycles are required to allow sufficient time for the zone to cool. Other strategies are based on using water or steam to directly cool the laser treatment zone.

What benefits will it bring to the food industry?

CO₂ Laser is a non-contact processing technology that has great potential to alleviate the problem of cross-contamination in the food industry.

It can be used on food for a wide range of applications including cooking/grilling, marking, cutting, peeling or inactivating microorganisms present on food contact surfaces.

To the author’s knowledge, the only fully industrialized and widespread laser application in the food market is the laser marking of fruits and vegetables, as it acts directly on the food.

However, the results obtained in other applications are promising and further efforts are needed to bring them to market.I have a CO today₂ A laser system with the power and characteristics needed to industrialize most of the applications described in this article.

Therefore, no major scaling issues are expected and we can foresee their industrial use starting to spread in the coming years.₂ Lasers are used in other industries, but their cost has dropped significantly over the last two decades.

With this in mind, the cheaper cost definitely makes it easier to implement in the food industry, where margins are lower than in other production sectors.

References

1. Puértolas, E., et al. (2020). Emerging extraction.of food waste collection, 219–240. 2nd Edition San Diego: Academic Press.
2. Watson, I., et al. (2007). Scanning CO₂ Laser bacteria inactivation system. Journal of Applied Microbiology 102:766–773.
3. Gracia, A. (2019). Laser cooking system applied to 3D food printing equipmentPhD thesis, Autonomous University of Barcelona.
4. Teng, X., et al. (2021). Potential applications of laser technology in food processing. Trends in food science and technology 118:711–722.
5. Fukuchi, K. et al. (2012). Laser Cooking: A new cooking technology for dry heating using a laser cutter and vision technology.of CEA ’12: Proceedings of the ACM Multimedia 2012 Workshop on Multimedia for Cooking and Eating Activities55–58.
6. Henze, N., T., et al. (2015). Enrich food with information.of MUM ’15: Proceedings of the 14th International Conference on Mobile and Ubiquitous Multimedia258–266.