Marzipan: Polymerase Chain Reaction-Driven Methods for Authenticity Control

Abstract

According to German food guidelines, almonds are the only oilseed ingredient allowed for the production of marzipan. Persipan is a marzipan surrogate in which the almonds are replaced by apricot or peach kernels. Cross-contamination of marzipan products with persipan may occur if both products are produced using the same production line. Adulterations or dilutions, respectively, of marzipan with other plant-derived products, for example, lupine or pea, have also been found. Almond and apricot plants are closely related. Consequently, classical analytical methods for the identification/differentiation often fail or are not sensitive enough to quantify apricot concentrations below 1%. Polymerase chain reaction (PCR)-based methods have been shown to enable the differentiation of closely related plant species in the past. These methods are characterized by high specificity and low detection limits. Isolation methods were developed and evaluated especially with respect to the matrix marzipan in terms of yield, purity, integrity, and amplificability of the isolated DNA. For the reliable detection of apricot, peach, pea, bean, lupine, soy, cashew, pistachio, and chickpea, qualitative standard and duplex PCR methods were developed and established. The applicability of these methods was tested by cross-reaction studies and analysis of spiked raw pastes. Contaminations at the level of 0.1% could be detected.

Omics approaches for food authentication

“…Many of the modern‐day customers act more emotional than rational by means of consuming, for example, only “regional,” “organic,” “fair trade,” “vegan,” or, on the other hand, animal products solely produced by adequate animal housing. Furthermore, labeling of species or varieties is often used for promotional issues, for example, fine cocoa versus low‐grade cocoa , marzipan versus persipan , or spelt versus wheat .…”

Original oder Fälschung?

“…Dinkelprodukte werden zum Teil mit Weizen gestreckt, um die Backeigenschaften zu verbessern, aber auch um Kosten zu sparen, da Dinkelmehl deutlich teurer ist . Ein weiteres Anwendungsbeispiel ist der Nachweis von billigem Konsumkakao, der u. a. zur Streckung von Edelkakao eingesetzt wird sowie der Zumischung von kostengünstigerem Persipan, welches aus Aprikosenkernen hergestellt wird, zu vergleichsweise teurem Marzipan, das aus Mandel gewonnen wird . Ebenso können gentechnisch veränderte Lebensmittel mit DNA‐basierten Methoden nachgewiesen werden.…”

Lebensmittelchemie 2011

“…Viele Lebensmittel enthalten Verbindungen, die als enzymatische Inhibitoren wirken und so enzymatische Verfahren wie die Polymerasekettenreaktion (PCR) stören 21. Bei der Herstellung eines Lebensmittels werden häufig Prozesse eingesetzt, welche die Struktur der DNA schädigen 22. Hohe Temperaturen, Fermentationsprozesse, saure oder basische pH‐Werte, aber auch mechanische Scherkräfte bei der Lebensmittelverarbeitung fragmentieren die DNA.…”