allergen management in the food industry (boye/allergen management) || processing of egg-free foods

259

9 PROCESSING OF EGG - FREE FOODS

Val é ry Dumont and Philippe Delahaut

9.1. INTRODUCTION

Thanks to a perfect balance of its components, egg is recognized universally as a basic commodity. In Europe, the average annual consumption of eggs is 210 per person. Production and consumption worldwide have tripled since the 1960s and continue to increase [1] .

Egg is an important ingredient of many food products because of its func-tional assets. This makes it diffi cult for allergic patients to avoid it. Egg allergy is generally accepted as one of the most common food allergies [2 – 4] , with an estimated prevalence varying from 0.2% to 7% [5] . After a presentation of egg and egg allergy, this chapter addresses the task of managing the allergen risk to produce egg - free foods.

9.2. GENERALITIES ON EGG AND EGG ALLERGY

9.2.1. Clinical Aspect of Egg Allergy

Egg allergy is one of the most common food allergies, affecting 1 – 2% of young children. In a study by Ranc é et al. [6] , of 544 children with a positive prick test and/or specifi c immunoglobulin E (IgE) and a positive food challenge, 36% displayed egg allergy (Fig. 9.1 ). The condition usually develops within the fi rst 2 years of life [4] . According to some studies, 50 – 58% of allergic children outgrow their allergy after the age of 5 years [1, 7] , but data from Savage

Allergen Management in the Food Industry, Edited by Joyce I. Boye and Samuel Benrejeb GodefroyCopyright © 2010 John Wiley & Sons, Inc.

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260 ALLERGEN MANAGEMENT IN THE FOOD INDUSTRY

et al. [8] suggest that this does not happen so early. The authors found that 4% developed tolerance by age 4. By age 6, 12% of egg - allergic children have outgrown their allergy. This increases to 37% by age 10, and 68% by age 16. Hen ’ s egg allergy is more signifi cant than allergy to eggs from other birds like goose and duck.

9.2.2. Egg Composition

Eggs are composed of 56 – 61% egg white and 27 – 32% egg yolk [9 – 11] . The relative proportion of each component varies according to the age of the hen and the environmental conditions. Egg white represents approximately two - thirds of the total weight of the egg without its shell, with water accounting for 87 – 89% of that weight. The remaining weight of the egg white comes from protein (9 – 11%), carbohydrates (0.8%), trace minerals (0.5%), lipids (0.1%), and vitamins. Egg yolk contains nearly 50% water, 32 – 35% lipid, and 16% protein. Minerals and carbohydrates are present in the egg yolk at 1.6% and 0.5%, respectively. Except for ribofl avin and niacin, most vitamins are present in the egg yolk.

9.2.3. Egg Proteins Responsible for Allergy

Although the major egg allergens are mainly contained in egg white, clinically relevant allergenic egg proteins have been identifi ed in both egg white and yolk [12, 13] .

Table 9.1 shows the molecular and biological properties of identifi ed egg allergens. Although ovalbumin seems to be one of the most studied antigens, it does not appear to be the most allergenic molecule [13] . Aabin et al. [15] reported the frequencies of reactivity of 53% for ovotransferrin, 38% for ovomucoid, 32% for ovalbumin, and 15% for lysozyme. In other studies, ovomucoid has been shown to be the dominant allergen in egg white [16] .

4.3%

35.7%

23.6%

8.3%6.0%

1.8%

1.5%1.5%

1.4%

EggPeanutCow's milkMustardCodHazelnutKiwi fruitWheatShrimpOthers

15.9%

Fig. 9.1 Frequency of food allergy to various foods in 544 children with positive prick tests and/or specifi c IgE and positive food challenge [6] .

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PROCESSING OF EGG-FREE FOODS 261

This discrepancy may be partly due to the use of impure proteins in some studies. Moreover, according to Walsh et al. [17] , the existence of different groups of patients reacting in a similar way to four discrete sets of purifi ed proteins may explain why various researchers have reported different allergens to be important in egg hypersensitivity. The four sets are as follows: set 1: the egg white proteins lysozyme and ovalbumin; set 2: the egg white protein ovo-mucoid; set 3: the egg white protein ovomucin; and set 4: the egg white protein ovotransferrin and the egg yolk proteins apovitellenin I, apovitellenin VI, and phosvitin.

9.2.3.1. Ovomucoid. Ovomucoid or Gal d1 forms about 11% of the egg white. It is a highly glycosylated protein, with 25% of its mass being attributed to carbohydrates. The protein consists of three structurally independent homologous domains [18] . An epitope mapping study has shown that specifi c immunoglobulin G (IgG) and IgE from patient sera bind to the whole ovomucoid molecule comprising all three domains [19] . It has been shown that the antigenicity and allergenicity of ovomucoid remain after fragmenta-tion by pepsin digestion [20, 21] . This protein is also thermolabile, and this has an impact on allergenicity: patients may be tolerant to cooked eggs while having severe allergic reactions to raw eggs [22] .

9.2.3.2. Ovalbumin. The most abundant and most studied protein in egg white is ovalbumin [13, 23] . This protein, also called Gal d2, is a phosphogly-coprotein. Its biological function is not really known. It has homology with the

TABLE 9.1 Molecular and Biological Properties of Identifi ed Egg Allergens [14]

Protein Name MW (kDa) Rel % (w/w) Biological Function

Egg white proteins Ovomucoid (Gal d1) 28 11 Trypsin inhibitor activity Ovalbumin (Gal d2) 44 54 Not really known Ovotransferrin (Gal d3) 78 12 Antimicrobial activity

Activation of immune system

Antioxidant properties Lysozyme (Gal d4) 14 3.4 Bacteriolytic activity Ovomucin 165 3.5 Antiviral activity

Egg yolk proteins Phosvitin 35 13.4 Cation - binding property

Antibacterial activity Antioxidant activity

α - Livetin (Gal d5) 69 9.3 Albumin Apovitellenins 9.5 – 170 37 Lipid - binding activity

MW, molecular weight; Rel % (w/w), relative proportion in weight compared with egg white

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serine protease inhibitor family, although it lacks any protease inhibitor activ-ity [24] . Pellegrini et al. [25] showed that proteolytic peptide fragments of ovalbumin display antimicrobial activity, whereas the whole protein itself is not bactericidal.

9.2.3.3. Ovotransferrin. Also called Gal d3 or conalbumin, ovotransferrin belongs to the homologous group of transferrins, which are single - chain bilobe proteins possessing an Fe + - binding site in each lobe [26, 27] . Its antimicrobial activity due to its iron - binding properties has been well investigated [28] . Other biological functions have been described, including activation of the immune system [29] and antioxidant properties [30] .

9.2.3.4. Lysozyme. Lysozyme or Gal d4 is a single polypeptide chain of 129 amino acids cross - linked by four disulfi de bridges [31, 32] . It can catalyze the hydrolysis of specifi c kinds of polysaccharides comprising the cell walls of bacteria [33 – 36] . It is thus widely used as a preservative in several foods and drugs.

9.2.3.5. Ovomucin. Ovomucin is a heavily glycosylated protein consisting of two subunits [37] . It maintains the structure and viscosity of the egg white [38] . It also displays properties such as antiviral activity [39] and immunoactivator activity [40] . Walsh et al. published the fi rst report on the in vitro allergenicity of this protein in 1988 [41] . This was also the fi rst time egg yolk proteins were described as allergens.

9.2.3.6. Egg Yolk Proteins. Although egg yolk proteins were previously believed to have no allergenicity potential, some studies have highlighted minor allergens among them [12, 17, 41] . Phosvitin is a highly phosphorylated molecule with a great cation - chelating capacity [42] . More than 90% of the iron in eggs is bound to phosvitin. Because of this property, phosvitin shows antibacterial [43] and antioxidant activities [44] . The protein α - livetin or Gal d5 is an egg yolk allergen also implicated in the bird - egg syndrome [45] . The third set of egg yolk allergens consists of apovitellinin - containing lipoproteins. Apovitellenins I and VI are reported to show IgE - binding activity [17] .

9.3. EGG: A MULTIFUNCTIONAL INGREDIENT IN THE FOOD INDUSTRY

Egg and egg components are widely used in many different food products, such as bakery products, sauces, ice cream, processed meat products, and pasta. They are also found in cosmetics, shampoos, and pharmaceuticals. Egg is a multifunctional ingredient: binder, coagulant, emulsifi er, preservative, and so on. Egg components may be used individually for specifi c applications in food preparation. For example, lysozyme is used as a preservative, lecithin as an

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emulsifi er, and provitamin A as a coloring. Yet, these egg - derived products are sources of allergens for egg - sensitive individuals.

Egg is available in different forms: whole egg powder, pouches of liquid eggs, only egg yolk powder or egg white powder, egg - derived products (leci-thin, lysozyme), egg proteins, and so on.

This can make it fairly complex to manage eggs or egg - derived products in an allergen control program.

9.4. MANAGING THE ALLERGEN RISK TO PRODUCE EGG - FREE FOODS

In order to make egg - free foodstuffs, food producers have to know how eggs end up in the fi nal product. Eggs may be incorporated into a product volun-tarily or involuntarily. In the fi rst case, it is necessary to know what function egg fulfi lls in the product, in order to fi nd substitutes. For instance, half a small, ripe, mashed banana could bring moisture equivalent to that afforded by an egg, and cooked oatmeal or potato starch could serve as a binder in the same manner as egg.

Another way to avoid a severe allergic reaction to egg - containing products is to render egg products hypoallergenic through food processing. Methods such as heat treatment, enzymatic fragmentation, irradiation, or a combination of these have been shown to reduce allergenicity [14, 45 – 47] . The main issue here is the risk of altering the functional properties of egg proteins. Moreover, this kind of treatment merely reduces allergenicity of egg - containing products but does not eliminate it. The only truly effective approach to eliminating egg allergy is total avoidance of the offending compound. This means developing food products that do not contain any trace of egg.

In dealing with food allergens like egg, the main task is to assess where the risk arises. Involuntary introduction of egg into a product can come from dif-ferent sources: human error, the raw material supplier, cross - contamination on the product lines, and so on. Contamination can be of two kinds: primary and secondary. Primary contamination occurs when a component used volun-tarily in a recipe is introduced into a product that should not contain it as, for example, when a processed meat product is prepared in a mixer after another product containing egg, without any cleaning step between the two products. The second product is thus contaminated with egg, and this is a primary con-tamination. Secondary contamination occurs when an allergen is involuntarily present in a component that is itself introduced involuntarily into a product. On a product line, for instance, a chocolate biscuit might be produced directly after an almond biscuit, and egg powder might have contaminated the almond paste used for the almond biscuit. In this example, the presence of egg in the almond biscuit and the presence of almond in the chocolate biscuit are primary contaminations, but the fortuitous presence of egg in the chocolate biscuit via the almond paste is a secondary contamination.

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Contamination can also be heterogeneous or homogeneous. Heterogeneous contamination is the most diffi cult contamination to assess and to manage. For instance, egg powder transported on employee clothing and falling into a non - egg - containing product is a heterogeneous contamination. Only a small amount of products is contaminated by batch. It could also be, for instance, only one cream injector for cakes that has not been well cleaned after egg - containing cream cakes have been produced. On a product line with eight injectors, the cakes from the seven well - cleaned injectors will not have been contaminated. The fi rst cakes from the contaminated injector will contain egg. After a while, the injector will be “ cleaned ” by dilution with the non - egg - containing cream and the last cakes could be without egg. The batch of those cakes presents heterogeneity of the contamination. Less than 12.5% of the production is contaminated by egg. Homogeneous contamination such as egg contaminating dough in a blender could be evaluated by analysis more easily than heterogeneous contamination. Indeed, each product of the batch contains the same amount of egg. A second example is an ingredient contaminated with egg used for the preparation of products. All products of the batch are con-taminated with egg.

Human error and employee ignorance about allergens are often the main causes of the fortuitous presence of allergens in food. The only solution is training and making each employee aware of what an allergen is. Employees have to know that allergens can be present in various forms: powder, liquid, small pieces. For some consumers, allergens are delicious foods, but for others they are life threatening. Each employee should know how to avoid accidental introduction of allergens into products upon leaving a cafeteria, for instance, or when shifting between two different production areas.

The second most important step in food allergen management is the han-dling of raw materials. Knowledge is of the essence. It is important to know what is in the fi nished product and what enters the factory. This means fi rst obtaining a food allergen declaration from each supplier of raw materials. This declaration could be a questionnaire transmitted with each raw material. It has to be checked via an audit and analyses. With complete information, raw materials could be segregated per allergen in dedicated and clearly labeled bags or containers. Tools used to handle allergenic products should also be identifi ed by color coding and/or label. One possibility is to dedicate a color to each allergen. For instance, red could be used for each utensil, bag, and tool used to handle egg or an egg - containing product, blue for milk, yellow for peanut, and so on.

The research and development department is another important place to assess and manage the risk of egg contamination. Each recipe should be evalu-ated in order to know the function of each component and the advantages of using it. It should be advantageous to avoid the use of allergenic food ingre-dients if other ingredients work just as well. As already mentioned, some substitutes for eggs exist, like banana, tofu, or cooked oatmeal. One should avoid using allergenic ingredients in such slight amount that they have no

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functional effect on the fi nished product. This happens sometimes, because some recipes have been used for many years without ever really being assessed. Eggs are perhaps added to the product to color it a little, and another food coloring could replace them easily. The same approach should be used when developing a new recipe. In conclusion, reformulation of old recipes and allergen - conscious development of new ones could even improve the fi nal product.

Engineering of the fi ttings and system design should also be considered in a control program. Whenever possible, one should favor accessible, “ visible ” fi ttings. If egg is a binder for the components of a product, it can also bind onto equipment walls, which can be adequately cleaned only if they are acces-sible. Flows of raw materials, semifi nished product, rework, and staff must be drawn. This is the best way to see if there are intersections between product lines, these being potential sources of contamination. The logistics should be precise in order to avoid wrong labeling and packaging – – staff might transport an allergen from one production line to another; containers that are supposed to carry one specifi c product might be reused for another product; the same line might be used to package different products. The system design must take into account the allergen problem. The best way to avoid cross - contamination is to make production as rectilinear as possible, without any intersections between production lines, from reception of raw materials to packaging of the fi nal product.

For consumers, reading the label is the only way to know what is in the product that they would like to eat. Food control agencies and public health commissions lay down labeling regulations such as the European Directive 2003/89 and its subsequent amendments, in order to inform allergic consumers of the presence of allergens in prepackaged foodstuffs. Yet for these consum-ers, the problem arises from cross - contamination, for which there is no legisla-tion. The majority of food producers prefer using precautionary labeling such as “ may contain ” instead of devising a real allergen control program; but autocontrol system and quality standards require a more documented risk assessment and management program for avoiding cross - contamination by food allergens.

Control of packaging and labeling is very important. Any change in the recipe should be mentioned clearly on the label, especially if a new allergen has been introduced. Discussion with the research and development depart-ment may be necessary to delay production of the new product in order to sell out all the old batches.

The name used for the component should clearly refer to the allergen. For instance, ovalbumin or lysozyme should be followed by a reference to egg. Finally, the right product has to be in the right package with the right label. At the end of production, for instance, a clear separation should be established between egg - containing products and others. If only one packaging line is available, products without eggs should be packaged fi rst. Before packaging of the other products begins, label and package changes should be checked.

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Production scheduling may be the best way to avoid cross - contamination. Most producers do not have one production line for each product they make, so there are intersections between fl ows. There are several easy ways to decrease the risk of contamination. One is to minimize changeovers. Long runs of allergenic products should be favored. This decreases the number of cleaning steps and increases profi tability. Another easy measure is to group together products containing the same source of allergens. For instance, all egg - containing products could be made, then all milk - containing products, and so on, if possible on different days. Production can be planned so as to start production of allergen - free products right after the cleaning step, these being followed by products with few allergens and fi nally by products containing the most allergens. Finally, to minimize and even eliminate the risk of contaminat-ing allergen - free products, it is best, if possible, to dedicate processing, person-nel, containers, tools, and so on, to products containing specifi c allergens.

Recycling of semifi nished products like dough or cutting wastes is common in the food industry, as avoiding it is too expensive. This rework should be viewed as raw material and processed as such. This applies to labeling, color coding, and storage. In this way, it should be easy to reintroduce the rework into production in a “ like into like ” manner, or better, in an “ exact into exact ” manner.

The last step in a food allergen management program is cleanup. Even if good planning makes it possible to minimize this step, no allergen control program can be set up without cleaning. Compared with the work and equip-ment needed, time for cleaning is the limiting factor. Cleaning is time – consuming, and time is money. The cleaning step should be determined according to the process used and products made. It is important to make the right choice of a cleanup system: wet or dry, in - place or out - of - place, scraping or cleaning. Push - through to “ rinse ” the production line could be a good solution to close the cleaning step, but it has to be tested to evaluate how much is necessary.

9.5. CONCLUSIONS

Allergen - free and particularly egg - free food processing is a complex issue. The omnipresence of egg and egg - derived components in cooked or manu-factured food products makes it hard to set up a food allergen control program. Yet the only effi cient way for allergic consumers to avoid an allergic reaction is complete elimination of the allergen in their diet. The food industry has a key role in developing foodstuffs safe for human consumption without neglecting the nutritional contribution and the diversity of diet. Overuse of precautionary labeling could have a negative impact on the behavior of aller-gic consumers: they might marginalize the labeling and decide despite every-thing to eat the products. To protect consumers, it is necessary to devise assessment and management schemes to avoid the risk of cross - contamination by food allergens.

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allergen management in the food industry (boye/allergen management) || processing of egg-free foods

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