Angelika Paschke

Stability of food allergens and allergenicity of processed foods

The allergenicity of food could be altered by several processing procedures. For various foods of animal and plant origin the available literature on this alteration is described. Investigations on hidden allergens in food products are also dealt with.

Determination and characterization of cross‐reacting allergens in latex, avocado, banana, and kiwi fruit

Sera of 11 patients were used to characterize allergens in kiwi fruit, latex, avocado, and banana by SDS‐PAGE/immunoblotting and to determine cross‐reactions between these allergen extracts in EAST inhibition and immunoblot inhibition. By SDS‐PAGE/immunoblotting. allergens with apparent molecular weights of 21, 38. 40. and 42 kDa were visualized in latex extract. In avocado extract. IgE‐binding components of 27, 43, 52, 58, 65, 75, and 88 kDa were to be seen, whereas, in banana extract, a 40‐kDa protein showed strong IgE binding. Furthermore, allergens of 52,58,88, and 94 kDa were detected in the extract of banana. Cross‐reactions between these allergen extracts were determined by EAST inhibition. Immunoblot inhibition demonstrated that almost all IgE‐reactive bands in nitrocellulose‐blotted latex, avocado, and banana extracts and two components of 43 and 67 kDa in kiwi fruit shared common IgE epitopes.

Stability of bovine allergens during food processing

OBJECTIVE The primary objective of this review was to summarize reported findings about the influence of various food manufacturing processes on the potential alteration of bovine allergens in cows milk, beef, and related food products. DATA SOURCES This review was based on literature research in two German databases. STUDY SELECTION The expert opinion of the authors was used to select the relevant data for the review. RESULTS Changes in allergenic activity during food processing are attributable to inactivation or destruction of epitope structures, formation of new epitopes, or improved access of previously hidden epitopes. The allergenic potency of food could be altered by several food manufacturing procedures--such as mechanical, purification, thermal, biochemical, and chemical processes. The main processing steps studied by investigators were heating (dry heating, boiling, or cooking) and enzymatic digestion. A review of the available literature on the alteration of bovine allergens in cows milk, meat, and related food products revealed reduction (but not elimination) of allergenicity by heating of cows milk for 10 minutes. Although homogenization did not change the allergenic potency of cows milk, it decreased the allergenicity of beef, as did freeze-drying. Digestion studies showed varied results. CONCLUSIONS The allergenicity of some food products decreased during certain processing steps, but the results of other investigations differed. Therefore, more systematic research on the influence of food processing on allergenicity should be undertaken.

Lysozyme in wine: A risk evaluation for consumers allergic to hen's egg.

Lysozyme used in wine production could present a risk for consumers allergic to hens egg. Thus, precautionary labeling of lysozyme on wines has been adopted within the European Community by updating Annex IIIa by Directive 2007/68/EC on November 27, 2007. Since no scientific data is known about the actual amounts and risks of lysozyme in wines, various in vitro efforts and skin prick tests were applied in this study to evaluate the presence of lysozyme in wines and the reactivity of those residues in allergic individuals and to fulfill the claim of updating Annex IIIa announced in Directive 2003/89/EC. Depending on the wines color (red or white wine) and fining with bentonite, which is known as an important step to remove unstable proteins mainly from white wines, diverse results were obtained concerning the amounts of lysozyme in finished wines and their in vitro and in vivo reactivity in humans allergic to hens egg.

Aspects of food processing and its effect on allergen structure

The article summarizes current physical and chemical methods in food processing as storage, preparation, separation, isolation or purification and thermal application on the one hand as well as enzymatic treatment on the other and their impact on the properties of food proteins. Novel methods of food processing like high pressure, electric field application or irradiation and their impact on food allergens are presented. The EU project REDALL (Reduced Allergenicity of Processed Foods, Containing Animal Allergens: QLK1-CT-2002-02687) showed that by a combination of enzyme and heat treatment the allergic potential of hens egg decreased about 100 fold. Clinical reactions do not appear anymore. An AiF-FV 12024 N project worked with fruits like mango, lychee and apple. Processed mango and lychee had no change in allergenic potential during heating while e. g. canning. Apple almost lost its allergenic potential after pasteurization in juice production.

Influence of varieties, storage and heat treatment on igE-binding proteins in hazelnuts (Corylus avellana)

The allergenicity of four hazelnut varieties (Runde Römer, Levantiner, Neapler, Contorta) and different types of heat treated and stored hazelnuts was examined and compared by SDSPAGE/immunoblotting and EAST-inhibition experiments using sera of 19 hazelnut allergic individuals. The immunoblot and EAST-inhibition investigations of the four varieties revealed only slight differences with regard to the allergenic activities. Heat treatment at 100°C for up to 90 min had no influence on the allergenicity of hazelnut prote ins. The IgE binding activity of the main hazelnut allergens decreased after 15 min heat treatment at temperatures between 100 and 185°C and was no longer detectable at 170°C. A protein < 14 kDa appeared to be very stable to heat and could be detected even after treatment at 185°C. Microwave treatment and storage of ground hazelnuts up to 19 weeks at room temperature had no influence on the allergenicity of hazelnut proteins.

Competitive Indirect ELISA for the Determination of Parvalbumins from Various Fish Species in Food Grade Fish Gelatins and Isinglass with PARV-19 Anti-parvalbumin Antibodies

Parvalbumins are well-known as major fish allergens. However, no quantitative analytical method is currently available for the determination of parvalbumins from different fish species. The aim of this study was the isolation of the various parvalbumins by the application of gel chromatography and dialysis and the development and validation of a competitive indirect ELISA for the determination of parvalbumins from various fish species. This ELISA method was applied to several fish gelatins and isinglass samples used in food production. The competitive ELISA was capable of detecting all tested parvalbumins within a range of 0.1-0.5 mg/L. No parvalbumin was detected in any of the investigated fish gelatins or in a fish skin used as raw material for fish gelatin production. Contrarily, isinglass was found to contain parvalbumin amounts of up to 414.7 +/- 30.6 mg/kg.

Allergenicity of hen's egg‐white proteins: IgE binding of native and deglycosylated ovomucoid

Ovomucoid (OM) is a major allergen of hens egg‐white. Carbohydrate moieties from the glycoprotein were removed by chemical deglycosylation. Deglycosylated ovomucoid (d‐OM) consists of five isoforms with molecular weights (MW) between 20.7 and 21.5 kDa whereas native OM has a MW of 28 kDa as determined by matrix‐assisted laser desorption/ionization time of flight mass spectrometry. The IgE‐binding properties of both proteins were investigated. All patients’ sera tested, showed strong IgE binding to both native OM and d‐OM in SDS‐PAGE/immunoblot. In enzyme‐allergosorbent test experiments, 50% inhibition of IgE binding was observed, at almost the same inhibitor concentrations of 67 and 57 ng ml‐1 for native OM and d‐OM respectively. Results indicate that only epitopes on the protein backbone are responsible for IgE binding while carbohydrate residues do not participate in allergenic structures of OM.

Determination of the IgE-binding activity of soy lecithin and refined and non-refined soybean oils

In the present study refined and non-refined soybean oils as well as soy lecithins were investigated for residual allergenicity and compared with extracts from native soybeans. By means of immunoblotting and EAST inhibition experiments no IgE-binding activity was detectable in refined soybean oils, which is probably due to thermal treatment during the refining. The investigated non-refined oils and soy lecithins showed a residual IgE-binding activity. In addition in the lecithin extracts a new IgE-binding structure with a molecular mass of approximately 16 kDa was detectable.

Characterization of cross‐reacting allergens in mango fruit

Background: Allergic reactions to mango fruit have become increasingly important. A cross‐reaction between mango fruit, various other foods, and respiratory allergens has been assumed but not investigated until now.