Controlling allergen removal from food sector workwear

20 April 2017

Food allergies are the curse of the 21st century as more and more people seem to be succumbing right left and centre. How can we best deal with eliminating allergens from workwear in the food sector? Richard Neale of LTC has the answers

The incidence of allergic reactions to certain food ingredients appears to be increasing, especially in some of the world’s more advanced economies. The anaphylactic shock produced by someone who is sensitised to, say, nut allergens can be out of all proportion to the quantity of allergen ingested. Just a tiny amount can make a sensitised customer seriously ill. This calls for demonstrable diligence on the part of food processors and their workwear providers.

Although nut allergens and peanut allergens, in particular, have received the most publicity, there is now a wide range of different allergens which are making life difficult for food producers and their suppliers of operative workwear.

This month we look at the different types of allergens, at the types of compounds which they comprise and the best methods for removing them reliably and completely from food workwear fabrics.

Different types of allergens

There are many hundreds of different allergens but food experts have isolated just 21 ‘marker’ allergens. If the launderer can successfully remove each of these, then it has been found reasonable to assume that the fabric is sufficiently allergen-free as to reduce to a very low level the risk of allergic reactions from sensitive consumers. The full list of the marker allergens currently being used is shown in the table (see table 1). If the microbiological assessment shows there is no detectable sign of any of these then the laundering process is assumed adequate.

What is an allergen?

An allergic reaction is usually caused by a particular protein that has been swallowed by a consumer who is sensitised to that particular allergen; even contact with the skin can cause a reaction. A tiny amount of the protein can cause a serious reaction to such a consumer, even though most of the population might find that they can eat a substantial amount of the same protein with no adverse reaction. Not all allergens affect all sensitised consumers – many people are sensitive to only one particular allergen. The largest number are probably those affected by peanuts, but milk, eggs, wheat, fish and soy often affect children. Adults might be more at risk from fish, shell fish, fruits which have a stone (such as peaches, plums, cherries and apricots) as well as nuts and seeds.

The main problem is the hypersensitivity which many display, which means that the launderer must reduce, to a very low level on the fabric, all the different ingredients of each potential allergen. A typical reaction might involve hives, wheezing, swelling, gastro-intestinal effects and can prove fatal in occasional cases. The underlying mechanisms which underlie such reactions remain a great mystery, so no early solution is in sight.

Power of the wash process

The main ingredients of an allergen will be proteinic, so the oil in a nut product for example must be removed completely, as must be the protein in this and in the rest of the nut. One indicator of the adequacy of removal is the degree of residual staining on the fabric, from the vegetable dye which the components of the nut usually contain.

The nut oil can usually be expected to have an HLB (hydrophilic-lipophilic balance) value in the range 9 to 13, but there could well be exceptions (in the vegetable oils used for spa products for example (for which the HLB value can go right down to 7 or even 6). This means that the launderer will need an emulsifier with a low, broad range. The type of emulsifier used for mineral oil on engineers’ overalls is unlikely to be adequate by itself.

It is also necessary that the wash process has sufficient suspending power to keep in suspension the soiling removed from the fabric, so that it all goes to drain at the end of the main wash, with no re-deposition onto the fabric. This is not always easy, because there is a natural electrochemical attraction between the removed soiling and the cloth surface and this must be overcome.

The detergent is the source of the suspending agent and the best detergent formulations provide agents which neutralise the electrochemical charges and wrap around the soiling in the liquor so as to physically prevent it from re-depositing.

The degree of re-deposition in any wash process is determined by measuring the long-term greying over 25 washes, using a standard laundry reflectometer.

This is why greying prevention should feature in workwear contracts; the ability to prevent this gives one differentiation between a good and poor launderer.

Many processes rely on dilution in the rinse zone to lower residual allergen concentrations to a safe level for all consumers.

This is straightforward in a washer extractor process, with typical liquor ratios of >7 litres water per kg dry textiles (>7 litre/kg) in each of three separate rinses. This gives a dilution ratio  of 90:1 for polycotton garments, which would reduce an allergen concentration of 100ppm down to a negligible 1ppm.

It is more of a problem in a low-liquor tunnel washer process, where the counter-current water flow in the rinse zone is often down below 4.5 litre/kg.

In these processes the launderer must rely on superior wash performance to remove and capture the allergen proteins, so that they can be flushed to drain, usually at the front of the main wash zone or the end of the pre-wash.

Measuring the power of the process

The effectiveness of any wash process can be measured using standard pre-soiled and calibrated test swatches for mixed protein, vegetable oil, vegetable dye, mineral oil and blood. A sixth test swatch of plain white fabric is used to give the level of re-deposition. The performance of the process with respect to each type of soiling can be reported numerically by measuring the reflectance of each of the test swatches after one wash in the target process. If the performance of the process, with respect to the survival of each of the 21 marker allergens listed earlier, is measured by microbiological analysis of test swabs taken from the cleaned fabric, then the allergen removal can be rated alongside the reflectance scores on the test swatches.

Measurement of the number of proteinic allergens from the 21 marker-species is not economic as a means of routine quality control. However, measurement of the reflectance of the laundry test swatches can be carried out cost-effectively and the results rated for adequacy of process performance. Because the numerical ‘pass’ score for the various test swatches varies, it has been found better to rate the scores with a green=satisfactory, amber=requires improvement and red=poor colour coding, which makes for simple auditing by customer auditors. These improvements in routine assessment of adequacy of wash process for allergen management and control are still in their infancy. The task has been complicated by the absence of any standard for the cleanliness of a workwear garment with respect to allergen retention. However, Project 20 from the LTC Research Programme is amassing a stock of reference data to strengthen the evidence base for the criteria now being used.

The outcomes of this research project mean that launderers can now rate the power of any workwear garment process on a regular basis, to determine its adequacy in relation to allergen removal, using a simple set of calibrated pre-soiled swatches. If the food sector auditor requires evidence of actual allergen removal power with respect to the 21 ‘marker’ allergens, this can also be supplied at the outset of a new contract and on an occasional basis going forward.

Pre-impregnated test swatches

Work has also started on a pre-impregnated set of test-swatches, mounted onto a single carrier cloth, each soiled with one of a wide range of foodstuffs known to contain high levels of particular allergens. These are being used to challenge any commercial wash process with respect to removal of every allergen type expected to be encountered in everyday food preparation. This test piece is designed to augment rather than replace the present method based on measuring the power of the wash process using calibrated swatches, described earlier.

The new set of test swatches is processed just once. Then each swatch is swabbed in the standard manner to enable precise assessment of the level of each of the key allergens remaining. The target is to reduce the level of each to below the detectable level in the laboratory, which is believed to be adequate to manage the risks described. The list of foodstuffs on the swatches is shown in the table (see table 2).

Use of this set of swatches now enables any launderer to provide specific reassurance to a new customer regarding the removal to an adequately low level of any of the wide range of actual food allergens carried by this test piece. This is particularly useful when the auditor asks for evidence that there was a known amount of a particular allergen present before washing and that this was actually eliminated by the wash process.


Progress to improve the management of cleanliness with respect to allergen removal has been rapid in the food industry workwear rental sector, aided by the early take-up of the new methods and by the co-operation of food industry auditors, who have made helpful suggestions. The absence of national or international regulation has probably helped rather than hindered this – the need is being addressed by those who understand the importance of the objective and who know what they are doing.


Food allergies

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