Werner Baltes

Allergic Sensitization to Native and Heated Celery Root in Pollen-Sensitive Patients Investigated by Skin Test and IgE Binding

The rates of sensitization and allergy to four birch pollen related plant foods were investigated in a group of 167 patients who were sensitive to at least one kind of pollen and one particular food. Sensitivity was concluded from a positive skin prick test or the determination of specific IgE, whereas allergy was based on anamnestic data. The positivity rates for sensitization and allergy, respectively, were: apple, 93 and 84%; hazelnut, 90 and 78%; celery, 70 and 14%; carrot, 60 and 37%. Comparative testing by skin prick test and enzyme allergosorbent test (EAST) with extract from native and microwaved (750 W, 30 min, 100 degrees C) celery root was performed on 46 of these patients. At least one positive test result (either prick test or EAST) was obtained for native celery in 36/46 (78%) and for heated celery in 20/46 (43%) of these patients. Although the concordance between the EAST and the skin test was very low, extended control experiments of both test procedures revealed no evidence for nonspecificity. Immunoblot analyses of extract from native celery and sera of 60 patients with a positive EAST (class > or = 2, > or = 0.7 U/ml) for celery resulted in the following rates of IgE binding to known cross-reactive celery allergens: Api g 1:33%, celery profilin: 17%; multiple bands most probably due to carbohydrate epitopes: 32%. The rate of binding to other allergens was below 10%. Since these three important structures are also present in birch pollen, no allergen could be identified as a candidate to mediate an exclusive celery/mugwort association. Investigation of extract from native and heated celery by immunoblotting pointed to a high lability of Api g 1, whereas profilin and carbohydrate epitopes appeared to be more resistant to heat. It has been concluded that sensitization to celery in German patients is without clinical significance in the majority of cases, in contrast to other birch-pollen-related plant foods such as apple and hazelnut. For the particular kind of extract used, neither the EAST nor the skin test alone represents an appropriate diagnostic method for testing sensitization to celery.

Influence of food processing on the immunochemical stability of celery allergens

Celery roots were processed by microwave heating, cooking, drying, γ-irradiation, ultra high pressure treatment and high voltage impulse treatment. The immunochemical stabilities of the three known allergenic structures of celery were tested with sera from patients who were sensitised to celery. In addition, rabbit antisera were used to detect the allergens profilin and Api g 1 on celery immunoblots. The specificity and reactivity of IgE from the patients sera were investigated by immunoblotting, by an enzyme allergosorbent test (EAST) and by dose-related IgE inhibition experiments. The results of all three methods agreed closely and indicated high antigenic and allergenic activity in native celery which was reduced by thermal processing. The heat-stability of the known celery allergens decreased in the following order: carbohydrate epitopes> profilin>Api g 1. In contrast, the allergenicity was only mildly reduced by non-thermal processing. The results obtained with human IgE were confirmed by an in vitro mediator-release assay that is based on rat basophil leukemia cells (RBL cells) which were passively sensitised with celery-specific murine IgE. With sera from mice that had been immunised with native celery, the native sample and non-thermal celery preparations elicited the strongest mediator release, whereas a weak response was obtained with samples from heat-processed celery. These results agreed closely with the data obtained in allergic patients whose IgE antibodies were directed against the major protein allergen Api g 1. Our results may be helpful in risk assessment and in selecting food preparations which can be consumed without symptoms by a subgroup of celery-allergic patients with a known sensitisation pattern. ©1997 SCI

Chemical changes in food by the maillard reaction

Abstract The Maillard reaction results from a reaction between reducing sugars and amino acids. Reactive intermediates are formed by a variety of pathways and these can yield both volatile flavour components and brown melanoidins of higher molecular weight. The formation of these compounds is desirable in the heating (cooking) of many food products (meat, coffee, bread) but their occurrence during storage is undesirable and leads to a reduction in quality. The mechanism of the Maillard reaction will be explained and the most important intermediates and reaction products will be pointed out and their properties described. Reaction conditions for the Maillard reaction and methods for its inhibition will be discussed together with a description of methods currently available for the early identification of the Maillard reaction in foods.

Allergy to fruits and vegetables in pollen‐sensitive patients: Allergen characterization by IgE immunoblotting and peroxidase staining

Allergies to several plant foods, i.e. apples, nuts, stone fruits, celery and spices, are highly associated with pollen allergies. The observed crossreactivities are due to structural similarities between food and pollen allergens. Using horseradish peroxidase (HRP) as the marker enzyme we have further developed and optimized a sensitive and specific immunoblotting procedure for the detection of human IgE antibodies specific to food and pollen proteins separated by SDS‐PAGE and immobilized on nitrocellulose blots. Our optimization studies involved four colour substrates and six buffer systems. The best results were obtained when 0.3% Tween 20 and no protein was used for membrane blocking, whereas blocking with proteins yielded high backgrounds. Immuno‐ detection amplification was accomplished by the following incubation steps: (a) sample (human serum); (b) secondary antibody; (c) biotinylated tertiary antibody; and (d) streptavidin‐HRP. Staining was performed with 3,3,5,5‐tetramethylbenzidine which is a...

Model reactions on roast aroma formation

ZusammenfassungDie Umsetzung von Serin mit Glucose oder Fructose bzw. mit Diacetyl oder Cycloten im Autoklaven bei 120 °C, 150 °C bzw. 180 °C führte insgesamt zur Identifizierung von 338 flüchtigen Verbindungen wie aliphatische und carbocyclische Carbonyle, Furane, Furanone, Pyranone, Phenole, Pyridine, Pyrazine und Pyrrole. Die Gehalte dieser Substanzklassen wurden bestimmt und verglichen. Serin bildet neben Glykolaldehyd auch Aminoethanol sowie einige aliphatische Aldehyde und ermöglicht so die Entstehung zahlreicher Reaktionsprodukte. Fructose setzt bei Erhitzen offenbar mehr Methylglyoxal frei als Glucose, bildet im übrigen aber gleiche Abbauprodukte. Allgemein bilden sich mit steigender Temperatur steigende Anzahlen und Mengen von Reaktionsprodukten, von denen einige wie z.B. Furyl- und Furfurylpyrazine bestimmte, zusätzliche intermolekulare Kondensationen voraussetzen. Diacetyl bildet offensichtlich bei 180 °C dimere Kondensationsprodukte, die dann zu benzolaromatischen Verbindungen bzw. 3-Hydroxy-2,5,6-trimethylpyridin, 2-Acetyl-4,5-dimethylfuran bzw. -pyrrol weiterreagieren. Cycloten bildet schon allein durch Kondensation, Wasserabspaltung bzw. Wasserstofftransfer zahlreiche Derivate. In Gegenwart von Serin bilden sie mit NH3 Amine, die zu Cyclopentapyrazinen bzw. Dicyclopentapyrazinen weiter reagieren. Es werden Mechanismen für die Bildung einer Reihe von Röstaromaprodukten wie Pyrrolalkanole, Pyrrolopyrazine sowie den bereits genannten Verbindungen vorgeschlagen.SummaryAfter reaction of serine with glucose, fructose, diacetyl or cyclotene in an autoclave at 120° C, 150° C, or 180° C 338 volatile compounds (aliphatic and carbocyclic carbonyls, furans, furanones, pyranones, phenols, pyridines, pyrazines and pyrroles) were identified. The total amounts of some of these compound classes were determined and compared. Serine forms, beside glycolic aldehyde, also aminoethanol and some aliphatic aldehydes which lead to the formation of a great many compounds. Fructose obviously forms, under same conditions, more methylglyoxal than glucose, but generally the degradation products are identical. With rising temperature the number and amounts of reaction products increased some of which, like furylpyrazine and furfurylpyrazine, additionally required special intermolecular condensations. Diacetyl at 180° C obviously forms dimeric condensation products which, by further reactions, yield benzene compounds, 3-hydroxy-2,5,6-trimethylpyridine, 2-acetyl-4,5-furan and 2-acetyl-4,5-pyrrole. Cyclotene itself forms during heating numerous derivatives by condensation-, dehydration- or hydrogentransfer reactions. By reaction with NH3 from serine, these derivatives formed imines which, by further reactions, yielded cyclopentapyrazines and dicyclopentapyrazines. Some mechanisms are proposed for the formation of pyrrolylalkanols, pyrrolopyrazines and products mentioned here.

Determination of lipoic acid in meat of commercial quality.

ZusammenfassungEs wurde eine empfindliche GC/MS-Methode zur Bestimmung des Liponsäuregehaltes in tierischem Gewebe entwickelt. Vor der Extraktion muß zunächst die am Protein gebundene Liponsäure von derε-Aminogruppe des Lysins abgespalten werden. Hierfür wurde die Hydrolyse mit verschiedenen organischen und anorganischen Säuren sowie proteolytischen Enzymen am synthetisierten Molekülε-Lipoyllysin getestet und optimiert. Die Veränderung derε-Lipoyllysin- und Liponsäurekonzentration wurde dabei mittels HPLC verfolgt. Die besten Ergebnisse lieferte die siebenstündige Hydrolyse in 2 mol H2SO4 bei 120 °C. Nach der Hydrolyse wurde die Liponsäure durch eine Diethylether/Natriumhydrogencarbonat/Diethylether-Extraktion isoliert und anschließend mit MBDSTFA für die gaschromatographische Untersuchung derivatisiert. Die höchsten Liponsäuregehalte in handelsüblichen Fleischproben konnten in Leber, Herz und Niere ermittelt werden, während in normalem Muskelgewebe die Gehalte niedriger lagen.AbstractFor the quantitative determination of lipoic acid in meat a sensitive GC/MS method in the chemical ionisation mode with methane as reactant gas has been developed. Firstly, the cleavage of protein-bound lipoic acid from theε-amino group of lysine residues was optimized by hydrolysing the synthesized model compoundε-lipoyllysine with several organic and inorganic acids and proteolytic enzymes. The concentrations of lipoyllysine and lipoic acid during this test hydrolysis were monitored by HPLC. Optimum hydrolytic conditions were heating at 120° C in 2 mol H2SO4 for seven hours. After tissue hydrolysis, the lipoic acid in the hydrolysate was separated by a diethylether/sodium bicarbonate/diethylether extraction and then derivatised for GC with MBDSTFA. The highest amounts of lipoic acid in meat of commercial quality were detected in liver, heart and kidney whereas in muscle tissues its content was lower.

Analysis of liquid smoke and smoked meat volatiles by headspace gas chromatography

Abstract Headspace samples of smoked sausages and bacon were analyzed and compared with headspace samples of a commercial liquid smoke flavoring, in efforts to determine components contributing to the aroma of smoked foods. Sensitivities were enhanced by methods permitting GC and GC/MS analysis of large headspace volumes without additional heat treatments or concentration steps. A series of monoterpene hydrocarbons dominated the volatiles of smoked meat products, but were not detected as components of the liquid smoke.

Apple Allergy: The cDNA Sequence of the Major Allergen of Apple, Determined by Performing PCR with a Primer Based on the N-Terminal Amino Acid Sequence, is Highly Homologous to the Sequence of the Major Birch Pollen Allergen

Considering the known N-terminal amino acid sequence of the major apple allergen, a polymerase chain reaction (PCR) primer was selected to amplify cDNA encoding this protein. A single PCR product was obtained, cloned into Escherichia coli and subsequently sequenced. The missing 5-end of the apple cDNA sequence was obtained by a 5-RACE method. The cDNA sequence showed 72% identity with the coding region of one of the known isoforms of Bet v 1, the major allergen of birch pollen. The deduced amino acid sequence resulted in a 158-residue protein with a calculated molecular mass of 17.5 kDa and 63% amino acid sequence identity to Bet v 1. In addition, further protein alignments showed a high degree of identity with allergens from other tree pollens and some pathogenesis-related proteins from food plants. According to international regulations the allergen was termed Mal d 1 for this protein, it being the first major allergen discovered and characterised in fruits of apple (Malus domestica).

Methode zur Bestimmung von Mutterkornalkaloiden in Lebensmitteln

SummaryA suitable method has been developed for the routine analysis of the ergot alkaloids ergometrine, ergometrinine, ergosine, ergosinine, ergotamine, ergotaminine, ergocornine, ergocorninine, α-ergocryptine, α-ergocryptinine,β-ergocryptine,β-ergocryptinine, ergocristine and ergocristinine in cereal products. The method consists of food extraction, cleaning of the crude extract by a modified form of the Extrelut method, and identification and quantitative determination of the alkaloids by high pressure liquid chromatography (HPLC). The results are confirmed by thin layer chromatography (TLC) and gaschromatography/mass spectrometry (GC/MS). Market investigations have shown contaminations in ecological as well as in conventional products, with rye products mainly being contaminated. Within the EEC, a maximum value of 0.05% ergot respectively a total alkaloid content of 1 mg/kg in cereals used for food production is prescribed. This value was not exceeded in any of the investigated samples.ZusammenfassungEs wurde eine für die Routineanalytik geeignete Methode zur Bestimmung der Mutterkornalkaloide Ergometrin, Ergometrinin, Ergosin, Ergosinin, Ergotamin, Ergotaminin, Ergocornin, Ergocorninin, α-Ergokryptin, α-Ergokryptinin,β-Ergokryptin,β-Ergokryptinin, Ergocristin und Ergocristinin in Getreideprodukten entwickelt. Die Methode besteht aus der Extraktion des Lebensmittels, der Reinigung des Rohextraktes mit einer modifizierten Form des Extrelut-Verfahrens und der Identifizierung und quantitativen Bestimmung der Alkaloide mittels HPLC. Zur Absicherung der qualitativen Ergebnisse wurden DC und GC/MS hinzugezogen. Marktuntersuchungen zeigten Kontaminationen sowohl bei alternativen als auch bei herkömmlichen Produkten, wobei der Befall bei Roggenerzeugnissen überwiegt. Die gemessenen Werte lassen indes erkennen, daß in keinem Falle die in der Europäischen Gemeinschaft geltende Interventionsgrenze von 0,05% Mutterkorn entsprechend 1 mg/kg Gesamtalkaloide erreicht wurde.

Untersuchungen zur Reaktion von Aminosäuren mita-Dicarbonylverbindungen

SummaryMixtures of amino acids were reacted witha-dicarbonyl compounds and the degradation rates were determined. The basic and hydroxy amino acids reacted strongly, the acidic and nonpolar amino acids less so. Variation of the reaction conditions as well as comparing the pk-values of thea-amino groups with the degradation rates showed that mainly substituents on thea-carbon atom and further functional groups were responsible for the reactivity of the amino acids.Zusammenfassung.Aminosäuren wurden im Gemisch mita-Dicarbonylverbindungen umgesetzt und die Abbauraten bestimmt. Die basischen und Hydroxyaminosäuren sowie Glycin reagierten stark, die sauren und apolaren Aminosäuren relativ schwach. Veränderung der Versuchsbedingungen sowie Vergleich der Abbauraten mit den pK-Werten dera-Aminogruppen zeigten, daß in erster Linie Substituenten ama-C-Atom und weitere funktionelle Gruppen für die Reaktivität der Aminosäuren verantwortlich sind.