European Food Research and Technology

“Hidden” peanut allergens in commercial foods pose a potential risk for peanut-allergic individuals. Sensitive and reliable analytical methods are urgently needed for detecting peanut in processed foods at low levels. We developed a peanut sandwich ELISA test kit by pairing two polyclonal sera against peanut proteins obtained from different spices. Its analytical performance of sensitivity, specificity, accuracy, trueness, and precision were evaluated, respectively. The limit of detection (LOD) was defined as 0.001 mg/kg, and no cross-reactivity was observed in 25 spices including legumes, tree nuts, and seeds. Besides, the mean recoveries in four spiked food matrixes ranged from 74.067 to 122.953%, and the recoveries of the three model foods incurred with peanut proteins were within the range of 80–120%. Acceptable results of repeatability and reproducibility were obtained referring to the AOAC standard. Moreover, it was verified to be capable of applying for detecting peanut residues in commercially available food products in the market and evaluating the food labels effectively. The study provides powerful technical support for the sensitive detection of peanut products for both food manufacturers and regulatory agencies.

Wurzelgemüse enthält Spuren bis geringe Mengen an Flavon(ol)-glykosiden, während die Blätter der gleichen Species zum Teil beträchtliche Gehalte (bis über 1 g/kg, berechnet als Aglykon) aufweisen. Rettiche, Kohlrüben, Schwarzwurzeln und Rote Beete enthielten < 1 mg/kg Kämpferol und/oder Quercetin, Möhren < 1 mg/kg Apigenin und Luteolin, Sellerie hingegen ca. 75 mg Apigenin/kg und ca. 14 mg Luteolin/kg, Meerrettich ca. 20 mg Kämpferol/kg und Radieschen 1–10 mg Kämpferol/kg als Glykoside. Dünnschichtchromatographisch wurden in Radieschenblättern der Sorte „Eiszapfen” neben Isoquercitrin (Quercetin-3-glucosid) je ein Quercetin-3-0-diglycosid und ein Kämpferol-0-diglykosid, beide mit den Zuckern Rhanmose und Arabinose, aufgefunden.

Die wichtigste Keimgruppe bei frischem Hackfleisch sind dieMicrococcaeae. Daneben stellenLaktobazillen, Pseudomonaden undEnterobakterien relativ hohe Floraanteile. In verdorbenem Hackfleisch wird die Bakterienflora durchLaktobazillen undPseudomonaden bestimmt.Enterobakterien spielen vor allem bei erhöhten Verderbstemperaturen (15°C) eine Rolle. Eine nähere Bearbeitung von 1076 Kulturen vonEnterobakterien und 915 Kulturen vonPseudomonaden führte zu folgenden Ergebnissen. DieEnterobakterienflora des Hackfleisches besteht im wesentlichen aus Vertretern vonEnterobacter liquefaciens, Erwinia, Citrobacter undKlebsiella. Dabei treten zum Zeitpunkt des Verderbs vor allemEnterobacter liquefaciens undErwinia in den Vordergrund. Grundsäich ähnelt sich jedoch dieEnterobakterien-Flora von frischem und verdorbenem Hackfleisch. Dasselbe gilt für diePseudomonasflora, die zu 60–70% ausPseudomonas fragi besteht. Die Gesamtkeimzahl des Hackfleisches unterliegt großSchwan kungen.

 The flavonoids present in the wastes and residues obtained during the industrial processing of lemons were characterized and quantified. Selected products of the juice-extraction line and essential-oil-recovery line were studied. Industrial lemon juice is characterized by containing hesperidin and eriocitrin as the main flavonoid glycosides (130 μg/ml), other minor flavanones and C-glycosylflavones. After the concentration process, the concentrated juice contained a 5-fold increase in the concentration of flavonoids, but some of the hesperidin present in the initial juice was lost. The flavanone glycosides were mainly concentrated in the peel and solid residues, where hesperidin was present as the prevailing flavonoid with concentrations of up to three times higher than those of eriocitrin. In liquid residues eriocitrin was the main flavonoid. The solid residues (peel and frit precipitates) were the most interesting sources for the industrial recovery of flavonoids (13 kg/t processed lemons).

A study was undertaken on Cacioricotta, a traditional Italian goat’s cheese obtained from overheated milk (90 °C) without use of starter. The profile of proteolysis in the artisanal type, made with vegetable coagulant (latex released from caprifig branches) as milk clotting agent, was compared to that of the “industrial” one, manufactured with calf rennet. Particular aim of the investigation was to study the differences and, possibly, establish a useful tool for distinguishing the two types of cheese. The study was based on the quantification of the water soluble, 15% TCA soluble and amino acid nitrogen fractions, RP-HPLC separation of low molecular weight peptides and their identification by mass spectrometry (MALDI-ToF MS). The use of fig latex was associated to higher amounts of the nitrogen fractions and to RP-HPLC chromatograms very rich in peptides, in contrast to an almost complete lack of peptides in the industrial counterpart. These results confirm the strong proteolyitic activity exerted by the caprifig clotting enzymes in spite of the intense overheating of the milk, which is considered to cause reduction of the rate of casein degradation in cheese. The MS-based identification of several peptides provided a support at the molecular level for the characterization of Cacioricotta made with this vegetable coagulant and could be useful for “tracing back” purposes. In conclusion, the peptide pattern determined by the use of caprifig for milk coagulation can be considered a particular feature of the artisanal Cacioricotta, giving confirmation of its vocation to EU protection as typical product.