Ochratoxins

Ochratoxins belong to a family of mycotoxins that are secondary metabolites of Aspergillus sp. and Penicillium sp. These toxins are derivatives of an isocoumarin moiety linked to phenylalanine by an amide bond.

Several types of ochratoxins occur naturally, namely, ochratoxin A, ochratoxin B (dechlorinated OTA) and ochratoxin C (ethylated OTA), and are often co-produced. Ochratoxin A (OTA) is the most prevalent toxin.

Studies show that this molecule can have several toxicological effects such as nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic.

Ochratoxin A (OTA) is the most abundant and hence the most commonly detected member but is also the most toxic of the three. OTA is found as a common contaminant of wide variety of cereals, vegetables, dried fruits, spices, coffee, fermented beverages and medicinal plants.

OTA is a weak organic acid with a pKa value of 7.1 and a molar mass of 403.8 g.mol-1. With crystalline structure varying from colorless to white, this molecule possess an intense green fluorescence under UV light in acid medium and blue fluorescence in alkaline conditions.

Ochratoxin A is a moderately stable molecule and is able to survive most food processing to some extent and may thus occur in consumer products.

In wines, OTA is the most studied mycotoxin, and the European Commission (by regulation 1881/2006) established as the maximum tolerable level in wines destined for human consumption a concentration of 2 µg kg−1.

Contamination can be produced from the early stages of the colonization of mycotoxigenic fungi in grapes to the final steps in the wine packaging process.
Ochratoxins