Occurrence of Ochratoxin A Contamination and Detection of Ochratoxigenic Aspergillus Species in Retail Samples of Dried Fruits and Nuts

Abstract

Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium and is a potential contaminant of a wide variety of food products. To determine the incidence of OTA contamination in dried fruits and tree nuts, retail packaged and bulk raisins, dates, figs, prunes, almonds, pistachios, and walnuts were collected from small and large supermarkets in seven areas of the United States between 2012 and 2014. Of the 665 samples analyzed, OTA was detected in 48 raisin samples, 4 fig samples, 4 pistachio samples, and 1 date sample. OTA contamination levels ranged from 0.28 to 15.34 ng/g in dried fruits and 1.87 to 890 ng/g in pistachios; two raisin samples and one pistachio sample exceeded the European Union regulatory limit of 10 ng/g. PCR detection of potential OTA-producing Aspergillus species revealed the presence of A. niger, A. welwitschiae, and A. carbonarius in 20, 7, and 7 of the 57 OTA-contaminated samples, respectively. However, OTA-producing A. carbonarius was isolated from only one raisin sample, and no other OTA-producing Aspergillus species were found. These results suggest that raisins are more frequently contaminated with low levels of OTA than are other dried fruits and nuts and that Aspergillus species are the likely source of that contamination.

A risk assessment of dietary Ochratoxin a in the United States

“…Palumbo et al (2015) described the OTA methodology and contamination observed in dried fruits and nuts; Lee and Ryu (2015) describe the OTA methodology and contamination observed in breakfast cereals; and Al-Taher et al (2017a,b) describe the OTA methodology and contamination observed in infant cereal, infant formula and milk. For materials and methodology for those foodstuffs, please refer to the cited references.…”

“…Samples included organic, traditional and imported products. Further description of the sampling methods and contamination of OTA in the sampled food commodities can be found in previous work conducted by our group (Lee and Ryu 2015; Palumbo et al 2015; Al-Taher et al 2017). Contamination values for wine, coffee, cocoa and pork are being reported for the first time in this risk assessment.…”

“… * Source of data: Lee and Ryu, 2015; Palumbo et al, 2015, Al-Taher et al 2017a,b. a , not applicable …”

“…In this analysis, we present our data on the concentrations of OTA in a variety of foods and drinks bought from grocery stores around the US during 2012 and 2013 (Lee and Ryu 2015; Palumbo et al 2015; Al-Taher et al 2017a,b). From these, we imputed the levels of exposure in the US, based on average levels of consumption across all US citizens as well as in a special group for those who were considered ‘regular consumers’.…”

Population Dynamics of Aspergillus Section Nigri Species on Vineyard Samples of Grapes and Raisins

“…Samples were homogenized by grinding in an electric food grinder, and 25 g of each was subsampled for OTA extraction. OTA was extracted according to the Vicam OchraTest protocol for raisins (Vicam, Milford, MA), as previously described (22). Extracts were analyzed by high-pressure liquid chromatography using an Agilent model 1260 system (Agilent Technologies, Santa Clara, CA) and a Prodigy ODS 3 column (5-lm particle size, 4.6 by 250 mm; Phenomenex, Inc., Torrance, CA), and OTA peaks were quantified relative to an OTA standard curve, as previously described (22).…”