Electrospray MS‐based characterization of β‐carbolines – mutagenic constituents of thermally processed meat

The β‐carbolines 1‐methyl‐9H‐pyrido [3,4‐b]indole and 9H‐pyrido[3,4b]indole have been implicated as having causative roles in a number of human diseases, such as Parkinson's disease and cancer. As they can be formed during the heating of protein‐rich food, a number of analytical methodologies have been proposed for their detection and quantification in foodstuff. For this purpose, LC‐MS and LC‐MS/MS have emerged as the most specific analytical methods, and the quantification is based on the occurrence of unusual ions, such as [M+H‐(H^?)]⁺ and [M+H‐2H]⁺. In this study, we have investigated the formation of these ions by accurate‐mass electrospray MS/MS and demonstrated that these ions are formed from gas‐phase ion‐molecule reactions between water vapor present in the collision cell and the protonated molecule of 1‐methyl‐9H‐pyrido [3,4‐b]indole and 9H‐pyrido[3,4b]indole. Although this reaction has been previously described for heterocyclic amine ions, it has been overlooked in the most of recent LC‐MS and LC‐MS/MS studies, and no complete data of the fragmentation are reported. Our results demonstrate that additional attention should be given with respect to eliminating water vapor residues in the mass spectrometer when analysis of β‐carbolines is performed, as this residue may affect the reliability in the results of quantification.     

Food allergy to apple and specific immunotherapy with birch pollen

Conflicting results concerning the effect of specific pollen immunotherapy (SIT) on allergy to plant foods have been reported. The aim of this study was to investigate the effect of SIT using a birch pollen extract on food allergy with focus on allergy to apple. Seventy-four birch pollen-allergic patients were included in a double-blind, double-dummy, and placebo-controlled comparison of sublingual-swallow (SLIT) and subcutaneous (SCIT) administration of a birch pollen extract. Sixty-nine percent of these patients reported allergy to apple. The clinical reactivity to apple was evaluated by open oral challenges with fresh apple and a questionnaire. The immunoglobulin E (IgE)-reactivity was assessed by skin prick test (SPT), specific IgE, and leukocyte histamine release (HR). Forty patients were included in the final evaluation of the effect of SIT. The challenges were positive in 9 (SCIT), 6 (SLIT), and 8 (placebo) patients after treatment compared to 10, 4, and 10 patients, respectively, before SIT. The symptom scores to apple during challenges decreased in all groups, but only significantly in the placebo group (p = 0.03). As evaluated by the questionnaire, the severity of food allergy in general did not change and there were no differences between the groups. In spite of a significant effect on seasonal hay fever symptoms and use of medication and decrease in IgE-reactivity, SIT was not accompanied by a significant decrease in the severity of allergy to apple compared to placebo. Therefore, oral allergy syndrome (OAS) to apple should not be considered as a main criterion for selecting patients for birch pollen immunotherapy at present.     

Influence of γ‐irradiation and maize lipids on the production of aflatoxin B1 by Aspergillus flavus

The effect of γ‐irradiation and maize lipids on aflatoxin B₁ production by Aspergillus flavus artificially inoculated into sterilized maize at reduced water activity (a_w 0.84) was investigated. By increasing the irradiation doses the total viable population of A. flavus decreased and the fungus was completely inhibited at 3.0 kGy. The amounts of aflatoxin B₁ were enhanced at irradiation dose levels 1.0 and 1.5 kGy in both full‐fat maize (FM) and defatted maize (DM) media and no aflatoxin B₁ production at 3.0 kGy γ‐irradiation over 45 days of storage was observed. The level in free lipids of FM decreased gradually, whereas free fatty acid values and fungal lipase activity increased markedly by increasing the storage periods. The free fatty acid values decreased by increasing the irradiation dose levels and there was a significant enhancement of fungal lipase activity at doses of 1.0 and 1.50 kGy. The ability of A. flavus to grow at a_w 0.84 and produce aflatoxin B₁ is related to the lipid composition of maize. The enhancement of aflatoxin B₁ at low doses was correlated to the enhancement of fungal lipase activity.     

A food matrix reduces digestion and absorption of food allergens in vivo

Scope: Food allergy is caused by primary (class 1) food allergens, e.g. Bos d 5 (cow's milk) and Cor a 8 (hazelnut) or secondary (class 2) food allergens, e.g. Mal d 1 (apple). The latter cannot sensitize susceptible individuals but can cause allergy due to immunological cross‐reactivity with homologous respiratory allergens. Here, we studied the effects of food matrix on gastrointestinal proteolysis, epithelial transport and in vivo absorption of class 1 and class 2 food allergens. Methods and results: Mal d 1 lost its IgE‐reactivity immediately after simulated gastric digestion whereas Bos d 5 and Cor a 8 did not. Only Cor a 8 maintained IgE‐binding capacity after simulated intestinal proteolysis. The presence of hazelnut and peanut extracts, which served as protein‐rich model food matrices, delayed gastrointestinal degradation and reduced epithelial transport rates of all allergens through CaCo‐2 monolayers. Finally, IgE‐reactive allergens were assessed at different time points in sera from rats fed with all three allergens with or without hazelnut extract. The levels of all allergens peaked 2 h after animals were fed without matrix and increased over 8 h after feeding. Conclusions: A protein‐rich food matrix delays gastrointestinal digestion and epithelial transport of food allergens and thereby may affect their sensitizing capacity and clinical symptoms.     

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 hen's 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 wine's 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 hen's egg.