Food safety considerations for robot system - overall hygienic design principles

Hygienic design of robotic automation solution helps food companies to eliminate the risk of microbial contamination. In a four-part series of articles, we zoom in the best hygienic practices to design robotic automation solutions. In this third part we outline some general principles for hygienic design.  

Within the framework of the project ColRobFood, we were interested in the challenges faced by Flemish companies in integrating robots in food production with the hygiene constraints in mind. We noticed that the problem of designing 'food-ready' robotic automation solutions is still open. With these blog series we will give you a summary of tips and tricks promoted by well-known organisations in hygienic design as EHEDG and 3-A SSI. 

Previously we listed some risks of contamination of food by the equipment. How can we now manage these hazards by design ? In this blog we propose an overview of the main points you should look at to evaluate the quality of a robot system from a hygienic point of view.

The first task is to determine what is to be considered a product contact surface in order to assure that the design will fully protect the product from contamination.
The European standard EN 1672-2, Food processing machinery - Basic concepts proposes to differentiate between three major Hygienic Design areas: food zone, splash zone and non-food zone.

Food zone, splash zone and non-food zone

The food zone is the area intended to be exposed intentionally or unintentionally to the product. It comprises the surfaces from which splashed product, condensate, liquids or material may drain, drop, diffuse or be drawn into the product or onto product contact surfaces or surfaces that come into contact with product contact surfaces of packaging materials. The splash zone and the non-food zone are not meant to be in contact with any food products. The technical design criteria may be less stringent than in the food area, provided the surfaces are still cleanable and, where required, capable of being disinfected.

Food zone, splash zone and non-food zone in robot system

Hygienic design principles address the design of equipment so that they can be easily cleaned and sanitised.

Materials used and their surface finishing

The materials used must be inert, non-adsorbent and approved for food contact. They must resist corrosion as well as chemical agents used in cleaning procedures. Material compatibility should be considered during the conception of a new equipment as well as by any design change to avoid galvanic corrosion.

Surfaces and joining points (weldings, boltings) must also be smooth without any defect such as spots, cracks or cavities. The EHEDG recommends surface roughness of less 0.8 µm in the food zone.

Surfaces must also be free from holes and folds.

Left: useless holes ; Right: avoid metal-on-metal (risk of corrosion) and horizontal surfaces (not self-draining surface)
(image: courtesy of Frank Moerman)

Machine construction

Food equipment should be designed and fabricated in such a way that stagnant zones and inaccessible areas are reduced to a minimum. Areas that cannot be reached must be designed so that no product or living microorganism can enter them from the outside, and that no organic material can accumulate inside.

All coupling surfaces must be continuous and flat.
Welding should be preferred over fixing with rivets or screw threads and bolts.
All surfaces require a minimum 3% slope to enable liquids to run off.

Moreover, auxiliary products (especially lubricants) must at no time come into direct contact with food.

Screws have been used only at the level of the robot arm to allow pneumatic hoses to be optionally connected for the grippers and on the electronics cover located at the foot of the robot. Cap screws with sealing rings; the joins and lids on the various robot components all have sealed covers to prevent the entry and accumulation of microorganisms and contamination into areas that are difficult to clean.
(Source: EHEDG yearbook 2017/2018)

Ease of cleaning

It must be possible to clean all parts that might come into direct contact with food before each production run. Otherwise it is necessary to use disposable parts. Equipment design and installation must therefore take into account the accessibility of all the areas that will be cleaned manually, as well as the possible automatic cleaning procedures of non-accessible areas.

Equipment’s instructions must detail which products and methods are specified for cleaning and sanitisation.

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Want to know more? Stay informed!

The team of Sirris experts can support you. So be sure to keep an eye on this series of articles. Any questions? Please contact us!

The last and 4th part of our blog series will outline some  principles for hygienic design of automation system, more specifically for robot systems as specified by 3-A Sanitary Standards.