Ochratoxin A contamination of coffee batches from Kenya in relation to cultivation methods and post-harvest processing treatments

Reduction in Ochratoxin A Occurrence in Coffee: From Good Practices to Biocontrol Agents

Ochratoxin A (OTA) is a mycotoxin mainly produced by Aspergillus section Circumdati and section Nigri across the coffee chain. OTA is nephrotoxic and is a threat to human health. This review summarizes current knowledge on how to reduce OTA concentration in coffee from farm to cup. After a brief introduction to the OTA occurrence in coffee, current good management practices are introduced. The core of this review focuses on biocontrol and microbial decontamination by lactic acid bacteria, yeasts and fungi, and their associated enzymes currently reported in the literature. Special attention is given to publications closest to in vivo applications of biocontrol agents and microbial OTA adsorption or degradation agents. Finally, this review provides an opinion on which future techniques to promote within the coffee supply chain.

Probabilistic Risk Assessment of Metals, Acrylamide and Ochratoxin A in Instant Coffee from Brazil, Colombia, Mexico and Peru

This study analysed the probabilistic risk to consumers associated with the presence of iAs, Cd, Cr, Hg, Pb, acrylamide (AA) and ochratoxin A (OTA) in instant coffee from Brazil, Colombia, Mexico and Peru. The results found iAs to be the metal with the highest concentrations (3.50 × 10-2 to 6.00 × 10-2 mg/kg), closely followed by Pb (1.70 × 10-2 to 2.70 × 10-2 mg/kg) and Cr (5.00 × 10-3 to 1.00 × 10-2 mg/kg), although these differences were not significant between countries. Cd and Hg were not detected. Focusing on AA, the concentrations ranged from 1.77 × 10-1 mg/kg (Peru) to 4.77 × 10-1 mg/kg (Brazil), while OTA ranged from 1.32 × 10-3 (Peru) to 1.77 × 10-3 mg/kg (Brazil) with significant differences between countries in both cases. As regards risk, the hazard quotient and hazard index were less than 1, meaning that the consumption of instant coffee represents a low level of concern for non-genotoxic effects. The results of the combination of margin of exposure and probability of exceedance indicated that the non-genotoxic effects of Pb, AA and OTA pose no threat. However, the probability values of suffering cancer from iAs and AA (between 1 × 10-6 and 1 × 10-4) indicated a moderate risk and that management measures should be taken.

Fungal Diversity and Evaluation of Ochratoxin A Content of Coffee from Three Cameroonian Regions

The present study had the objective to assess the ochratoxin A content of coffee through chromatographic analysis and design a method using PCR-DGGE to analyze at the same moment the totality of fungal flora present in the coffee samples in order to determine their geographic origin. 96 samples of coffee were collected from the west region (Bafoussam and Dschang), centre region (Bafia), and east region (Batouri) of Cameroon during two years (2017 and 2018). Two treatments (dry and wet routes) were evaluated at three different steps of coffee processing (parchment coffee, green coffee, and husk coffee). The characterization of the fungal profile was done with PCR-DGGE and sequencing. The levels of OTA were assessed using HPLC analysis. The results indicated that the toxinogenic mycoflora associated with coffee beans was mainly Aspergillus niger, A. carbonarius, and A. ochraceus. PCR-DGGE data revealed that each sampling site is characterized by a specific fungal profile. Despite the influence of the treatment on the fungal population of coffee, bands common to samples coming from the same site were observed. These bands could therefore constitute potential biological markers to trace back to the origin of coffee. OTA was detected in most of the coffee samples analyzed and only few samples contented OTA at levels higher than the maximum tolerable limit for food intended for human consumption. The OTA content of coffee was significantly influenced by the sampling step and the sampling period.

Differentiation and quantification of the ochratoxin A producers Aspergillus ochraceus and Aspergillus westerdijkiae using PCR-DGGE

Ochratoxin A (OTA) is a nephrotoxic, teratogenic, immunotoxic, and carcinogenic mycotoxin which is produced in tropical zones mainly by Aspergillus carbonarius, A. niger, A. ochraceus, and A. westerdijkiae. A. ochraceus and A. westerdijkiae species are phenotypically and genomically very close but A. westerdijkiae produce OTA at a very higher level than A. ochraceus. These species have been differentiated recently. The DNA primer pairs which were drawn so far are not specific and a genomic region of the same size is amplified for both species or they are too specific, and in this case, the DNA of a single species is amplified. To help preventing OTA contamination of foodstuffs, the PCR-DGGE (Denaturing Gradient Gel Electrophoresis) method was used to discriminate between A. ochraceus and A. westerdijkiae DNA fragments of the same size but with different sequences and thus faster access to a diagnosis of the toxigenic potential of the fungal microflora. The proposed methodology was able to differentiate A. westerdijkiae from A. ochraceus with only one primer pairs in a single run. A calibration based on initial DNA content was obtained from image analysis of the DGGE gels and a method of quantification of the two strains was proposed.

Effect of post-harvest treatments on the occurrence of ochratoxin A in raw cocoa beans

Cocoa beans are the principal raw material for chocolate manufacture. Moulds have an important place in the change in the quality of cocoa beans due to their role in the production of free fatty acids and mycotoxins, namely ochratoxin A (OTA). This study investigated the impact of the key post-harvest treatments, namely the fermentation and drying methods on OTA contamination of raw cocoa beans. Analytical methods for OTA detection were based on solid-liquid extraction, clean-up using an immunoaffinity column, and identification by reversed-phase HPLC with fluorescence detection. Of a total of 104 randomly selected cocoa samples analysed, 32% had OTA contents above 2 µg kg(-1). Cocoa sourced from pods in a bad state of health had a maximum OTA content of 39.2 µg kg(-1), while that obtained from healthy pods recorded 11.2 µg kg(-1). The production of OTA in cocoa beans increased according to the pod-opening delay and reached 39.2 µg kg(-1) after an opening delay of 7 days after harvest, while 6.1 and 11.2 µg kg(-1) were observed when pods were opened after 0 and 4 days. OTA production also seemed to depend considerably to the cocoa fermentation materials. When using plastic boxes for bean fermentation, the OTA production was enhanced and reached an average OTA content of about 4.9 µg kg(-1), while the raw cocoa treated in banana leaves and wooden boxes recorded 1.6 and 2.2 µg kg(-1) on average respectively. In parallel, the OTA production was not really influenced by either the mixing or the duration of the fermentation or the drying materials.

An overview on mycotoxin contamination of foods in Africa

Mycotoxins are fungal secondary metabolites that contaminate various feedstuffs and agricultural crops. The contamination of food by mycotoxins can occur before production, during storage, processing, transportation or marketing of the food products. High temperature, moisture content and water activity are among the predisposing factors that facilitate the production of mycotoxins in food. Aflatoxins, ochratoxins, fumonisins, deoxynivalenol and zearalenone are all considered the major mycotoxins produced in food and feedstuffs. In Africa, mycotoxin contamination is considered to be a major problem with implications that affect human and animal health and economy. Aflatoxin-related hepatic diseases are reported in many African countries. Ochratoxin and fumonisin toxicity in humans and animals is widespread in Africa. The available, updated information on the incidence of mycotoxin contamination, decontamination and its public health importance in Africa is lacking. The aim of this review is to highlight, update and discuss the available information on the incidence of mycotoxins in African countries. The public health implications and the recommended strategies for control of mycotoxins in food and agricultural crops are also discussed.

Influence of post-harvest processing on ochratoxin A content in cocoa and on consumer exposure in Cameroon

Ochratoxin A (OTA) is a mycotoxin that contaminates several foodstuffs, including cocoa. It has nephrotoxic, teratogenic and carcinogenic properties in humans. The effect of post-harvest processing and storage on the OTA contamination of cocoa was studied over three successive cocoa seasons (2005, 2006 and 2007) in Cameroon. The type of fermentation (box or heap) did not significantly influence bean OTA content, which varied from undetectable (<0.03 ng/g) to 0.25 ng/g, remaining below 2 ng/g (the defined standard for cocoa beans). However, pod damage and late pod opening were aggravating factors for OTA contamination of cocoa. If pods were not intact (intentionally or naturally damaged), OTA was found in samples with contents of up to 75.5 ng/g before processing and 32.2 ng/g after 4 months' storage. This contamination exceeded the levels tolerated for export. In addition, some of the cocoa produced is processed locally and consumed as chocolate, cocoa powder, chocolate filled sweets, cocoa-based drinks and cocoa butter. In Cameroon, the average daily consumption of cocoa by-products is estimated at 0.75 g/d for adults and 1 g/d for children. Consequently, for maximum OTA contamination of cocoa beans, the maximum daily exposure to OTA would be 1.61 ng/kg bw/d in young children weighing around 20 kg, greatly contributing to the exposure of young consumers.