From a packaging perspective, modified atmosphere packaging (MAP) is an excellent example of packaging being used to increase the shelf life of fresh and refrigerated food products. Behind the scenes, however, it is automation, usually in the form of a laser, which produces the tiny holes that allow the packaging to help control and extend shelf life.
We might think of these as just humble holes, but the reality is quite different. Hole size, shape and position need to be controlled to micron dimensions to provide the specific functionality required for a diverse range of applications.
The growth in the healthy foods and snacks markets has further driven the requirement for not only attractive presentation, but extended shelf life for products such as organic fruit, vegetables, nuts, dried fruit and cereals. The freshness of these products is largely determined by air-ventilation and the preservation of humidity within the packaging and ultimately, this is achieved by the use of the latest laser technology that can often be found integrated within the packaging material production lines.
There is no doubt that packaging, helped by automation, plays a significant part in maintaining and extending the freshness of produce, however, there are many other instances, especially much earlier in the production process, where the use of automation brings tangible benefits to product quality, consistency and ultimately shelf life.
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However, where product needs to be handled and humans are involved, there are greater opportunities for contamination even from small amounts of bacteria which may be present on the person despite well-disciplined cleaning regimes.
The production of ready to eat meat products can be used as an example to illustrate the importance of hygiene and its potential effects on shelf life. During the large scale slicing and packing of ready to eat meat products, the control of hygiene in the packing area is paramount to keeping the initial bacterial loadings under control. Typically meat is sliced on a high speed automated slicing machine and it is then placed into its pack by operatives working on the production line.
Potential sources of contamination in the slicing and packing operation are controlled by the application of rigorous hygiene to all surfaces that contact the meat product. Slicing blades, conveyors and other equipment is cleaned and sanitised on a regular basis to prevent them becoming a source of contamination. The hygiene in the packing area is actively managed and monitored to ensure that issues do not occur.
One potential source of contamination in the packing area is more difficult to monitor and manage than the hard surfaces—people. They are potential sources of bacteria and contamination and in a manual packing operation, they come into contact with every slice of meat being packed.
People carry bacteria on their skin and hair and in their noses and mouths. This bacteria is a potential source of contamination on ready to eat foods and must be controlled if the safety and shelf life of the food is to be protected or extended.
Contamination ControlHumans are recognised in the food industry as being a large potential source of bacterial contamination of food products. This is especially the case where the operative manually handles the food product during its processing or packing operations. As you would expect, systems have been devised to minimise the risk of contamination and reduce the initial bacterial loads on the products. The initial bacterial load is a key factor in the shelf life of all fresh foods.
Typical methods used in the ready to eat meat industry to control and manage bacterial contamination from operatives include the use of personal protection equipment (PPE), such as hairnets, masks, overalls, boots and gloves.
There is, however, a cost for the provision of this equipment and the subsequent laundry costs for the re-useable items. The management of changing areas and locker rooms is also significant and adds further to the overall impact of the control of potential contamination from human sources.
Hand SanitisationThe hand washing and personal hygiene regimes within high risk packing areas are vital to minimising bacterial contamination risk. In a manually packed environment, the food contact surfaces include the hands of the operators as well as the conveyors and other equipment.
It is the hands that are likely to spread contamination throughout the area if the disciplines are not well managed. Hands have particular issues when it comes to maintaining them as a hygienic food contact surface. Hands can be difficult to clean because the surface is soft and contains pores that entrap bacteria.
Hand sanitation is also difficult because the chemicals that can be used need to be mild and not attack the skin surface. These issues are helped with the use of gloves to provide a barrier but these too are not easy to keep clean over the period of a shift.
The final issue around hands is temperature. Typically, the surface temperature of a gloved hand in a refrigerated area is around 20 to 22 deg C and this has an incubation effect on any bacteria on the surface of the glove. In the space of four hours, the number of bacteria can double, leading to potential contamination of all products handled. This risk is often managed by a ‘glove changing procedure’ to prevent the build-up of bacterial numbers.
Automation SolutionAutomation by comparison can significantly reduce and in certain instances, eliminate the potential for bacterial contamination. The uptake of automation within the food industry continues to increase as robots become faster and vision systems are now commonly used to identify the position and orientation of products, allowing them to be picked, processed and handled automatically.
The benefits of using robots for these often-monotonous tasks extend far beyond the obvious speed and repeatability gains. Robots, together with their gripping systems, are permanently sited within a clean and controlled environment and are therefore much less likely to contaminate produce during handling.
Robots and automation systems by their very nature are immune to the infections that we humans suffer. Robots do not ‘catch cold and flu’ and as they never leave the clean environment, do not pose the risk of ‘bringing an infection to work’.
Additional benefits from robot systems are the fact that the materials from which the grippers are manufactured, such as stainless steel, are easy to clean. Grippers, especially those to be used in a high risk/high care environment, are always designed to avoid potential traps for contamination.
Robot systems can also be programmed to perform cleaning routines at pre-determined intervals to maintain high standards of cleanliness in demanding environments. Certain types of robot grippers, in particular those using the Bernoulli principle, allow delicate foodstuffs to be moved without contact with the gripper. This not only ensures product integrity, but also eliminates the potential for contamination that might in turn adversely affect shelf life.
Furthermore, robots within high risk/high care environments are also able to work in much lower temperatures than humans, typically five to eight deg C. This lower ambient temperature maintains tighter control over bacterial growth on the food contact surfaces and in turn leads to lower initial loadings of bacterial during packing operations. All of these factors combine to improve shelf life for a particular product.
Water Jet CutFor many years, the traditional method of cutting and portioning fresh product such as lettuce and celery has been to use high-speed circular blades to perform the ‘top & tail’ and portioning or cut to length operations.
While effective, this technology can have a negative impact on the quality and appearance of the portioned item, especially if the blades start to blunt, causing bruising and/or leaving unsightly marks on the portioned product. A further drawback of this technology was the potential for contamination from material retained on the blades.
A highly effective alternative to conventional blade cutting systems is water jet. This type of system uses a high pressure pump to generate pressures of around 60,000psi. The water is delivered, via a nozzle with a diameter of just 0.15mm and travelling at over three times the speed of sound.
When used to cut delicate produce, the cells and surrounding material are left un-damaged as there are no compressive forces applied during cutting. Further benefits are the fact that the jet of water is always ‘sharp’ and the high pressures used eliminate any risk of bacterial contamination. The result is not only a product that looks great, but the cleanliness of the process also extends shelf life.
Systems of this type have also changed the way in which produce is handled. Traditionally, produce may have been cut by hand at the time of picking, giving rise to variations in the consistency and quality of cut and extending the time between cutting and packing. With a high-speed water jet system, the cutting process can be localised with the benefits of consistency and reducing to a minimum the time between cutting and packing.
It is clear therefore, that robotics, automation and the processes which they perform can and do play an important part in ensuring that the quality, presentation, shelf life and most importantly the safety of the food which we eat, is maintained.