Consumers with food allergies often react adversely to the ingestion of extremely low amounts of the offending food or foods that elicit their symptoms. The threshold dose needed to provoke an allergic reaction is not precisely known and is likely to vary from one allergic individual to another. However, given that reactions in the most sensitive individuals can occur from ingestion of trace amounts of the offending food, food processors must be very cautious about the use of shared equipment.

Food processors must often use shared equipment for related food products of differing formulations. The proper management of the use of such shared equipment is essential to prevent cross contact that would allow potentially hazardous residues of an allergenic food into another product where they should not be present.

Several strategies exist with respect to the use of shared equipment and shared facilities. Dedicating one or a few lines to the manufacture of formulations containing a particular allergenic food is one such strategy. For example, all peanut-containing formulations could be made on one dedicated line. This allows the establishment of "peanut-free lines" where the possibility of cross contact is lessened. When establishing "allergen-free" lines, great care must be taken to remove all residues of the allergenic food that might exist from prior use of this equipment. This may require complete disassembly and very thorough cleaning. Even the replacement of some parts of the manufacturing line may be considered. Of course, the situation is much easier if the equipment for the "allergen-free" line is new. When establishing "allergen-free" lines, great care must be taken in assuring that no cross contact can occur from allergen-containing lines that may be adjacent or certainly within the same building. Curtains or other temporary walls will help to prevent cross contact. Points where the lines might cross one another certainly must be avoided.

In certain manufacturing operations, the use of dedicated lines or equipment can be somewhat more complicated. In chocolate manufacturing, the use of enrobers is a particular issue worthy of mention. If an enrober is used for enrobing chocolate onto an allergen-containing product, the collected enrobing chocolate may contain residues of the allergenic food. The enrobing chocolate must be kept dedicated to use with that particular allergen to avoid cross contact. Thus, dedicated enrobers would be the ideal solution.

When a company has multiple facilities, the restriction of the manufacture of certain allergenic formulations to one of these facilities is an obvious strategy. Clearly, this may increase transportation costs, but this extra cost may be offset by the lowering of the risk of cross contact. Cleaning operations are also less burdensome in such situations. Several companies have chosen to dedicate one or a few facilities to the processing of peanut-containing products.

Another strategy involves addition of the allergenic ingredient into the product as late in the manufacturing as possible. In this manner, the amount of equipment that must be carefully cleaned to avoid cross contact can be minimized. Of course, this is not always possible, but should always be considered.

Certainly, the scheduling of processing operations can be a key strategy. Scheduling of the most allergenic product formulation just before the end of a shift with a major clean-up is a sensible approach. If line separation cannot be achieved, then process the peanut-containing formulation last in a series of formulations. Similarly, scheduling long runs of the allergenic product formulation is another useful strategy. This approach limits the number of clean-up operations.

Whenever shared equipment is utilized, effective clean-up must occur between manufacture of an allergenic formulation and manufacture of the next product. Clean-up strategies will vary with the nature of the products being manufactured and the design and composition of the processing equipment. Certainly, the challenges are greatest with processing operations that must be cleaned without the use of water or aqueous detergents.

How clean is clean enough? That question is difficult to answer. At a minimum, all visible residues of the allergenic product must be removed. While this sounds simple, verification of visibly clean can involve disassembly of certain pieces of equipment. It certainly involves very thorough inspections of places where residues might accumulate such as square corners and crevices. In some manufacturing operations such as the use of long baking ovens, the assessment of visibly clean can be extremely difficult.

The first product manufactured after changeover of formulations is most likely to be contaminated with allergenic residues. In some situations, sensitive and specific immunoassays are available for the assessment of the effectiveness of clean-up (a subject of a later article in this series). Currently, good assays are commercially available for peanut, egg, and wheat. Additional assays exist for casein (milk) and almond but are not yet commercially available. Analysis of the first products manufactured after changeover gives additional assurance that clean-up practices are adequate. In some situations, discarding of the first product manufactured after changeover can be an additional safeguard but it can be difficult to know if this is necessary if thorough cleaning has been attempted. In some manufacturing situation, contaminated product may appear episodically for hours after changeover. These "spikes" of contamination can be due to equipment design where allergen-containing product can be hung up for long periods and then break loose at various times contaminating subsequent product.

Some companies employ push-through in certain situations to remove product that contains highly allergenic ingredients. Push-through with salt or other inert materials can work well in some situations. However, when dealing with viscous materials such as molten chocolate, push-through may not be effective due to concentric flow in cylindrical pipes. The amount of push-through needed for effective removal of the allergenic food may be too large in such situations. Clearly, analysis for residues is a wise step in assessing the effectiveness of push-through when specific tests are available.

The manufacturing of allergenic formulations on shared equipment or facilities with other related formulations is clearly possible. The key good manufacturing practices are dedication of lines or specific pieces of equipment, appropriate scheduling of manufacturing operations, and effective clean-up between products. The assessment of the effectiveness of these strategies through the use of sensitive and specific immunoassays is advocated where such tests are available. In other situations, the standard must be visibly clean.

by Steve L. Taylor, Ph.D. and Susan L. Hefle, Ph.D.
Food Allergy Research & Resource Program
University of Nebraska
Lincoln, Nebraska, USA

This article is taken from Leatherhead Food RA's"Food Allergy and Intolerance: a Journal for World Food Industry".

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