Fumonisin B2 by Aspergillus niger in the grape–wine chain: an additional potential mycotoxicological risk

Mycotoxins in Functional Beverages: A Review

Consumer dietary habits have drastically changed in recent decades and functional beverages now have a strong position in the market. The majority of these beverages are produced using simple processes that use raw products, such as cereals, legumes, fruits, and nuts, among others, and these are known to be frequently contaminated with mycotoxins. This review is focused on the occurrence of these toxic compounds in plant-based milks, fruit juices, and herbal teas. The fate of the toxins during processing is discussed to establish the potential risk posed by the consumption of these kind of beverages regarding mycotoxin uptake.

Toxicological and Medical Aspects of Aspergillus-Derived Mycotoxins Entering the Feed and Food Chain

Due to Earth's changing climate, the ongoing and foreseeable spreading of mycotoxigenic Aspergillus species has increased the possibility of mycotoxin contamination in the feed and food production chain. These harmful mycotoxins have aroused serious health and economic problems since their first appearance. The most potent Aspergillus-derived mycotoxins include aflatoxins, ochratoxins, gliotoxin, fumonisins, sterigmatocystin, and patulin. Some of them can be found in dairy products, mainly in milk and cheese, as well as in fresh and especially in dried fruits and vegetables, in nut products, typically in groundnuts, in oil seeds, in coffee beans, in different grain products, like rice, wheat, barley, rye, and frequently in maize and, furthermore, even in the liver of livestock fed by mycotoxin-contaminated forage. Though the mycotoxins present in the feed and food chain are well documented, the human physiological effects of mycotoxin exposure are not yet fully understood. It is known that mycotoxins have nephrotoxic, genotoxic, teratogenic, carcinogenic, and cytotoxic properties and, as a consequence, these toxins may cause liver carcinomas, renal dysfunctions, and also immunosuppressed states. The deleterious physiological effects of mycotoxins on humans are still a first-priority question. In food production and also in the case of acute and chronic poisoning, there are possibilities to set suitable food safety measures into operation to minimize the effects of mycotoxin contaminations. On the other hand, preventive actions are always better, due to the multivariate nature of mycotoxin exposures. In this review, the occurrence and toxicological features of major Aspergillus-derived mycotoxins are summarized and, furthermore, the possibilities of treatments in the medical practice to heal the deleterious consequences of acute and/or chronic exposures are presented.

Appropriateness to set a group health-based guidance value for fumonisins and their modified forms

The EFSA Panel on Contaminants in the Food Chain (CONTAM) established a tolerable daily intake (TDI) for fumonisin B1 (FB 1) of 1.0 μg/kg body weight (bw) per day based on increased incidence of megalocytic hepatocytes found in a chronic study with mice. The CONTAM Panel considered the limited data available on toxicity and mode of action and structural similarities of FB 2-6 and found it appropriate to include FB 2, FB 3 and FB 4 in a group TDI with FB 1. Modified forms of FBs are phase I and phase II metabolites formed in fungi, infested plants or farm animals. Modified forms also arise from food or feed processing, and include covalent adducts with matrix constituents. Non-covalently bound forms are not considered as modified forms. Modified forms of FBs identified are hydrolysed FB 1-4 (HFB 1-4), partially hydrolysed FB 1-2 (pHFB 1-2), N-(carboxymethyl)-FB 1-3 (NCM-FB 1-3), N-(1-deoxy-d-fructos-1-yl)-FB 1 (NDF-FB 1), O-fatty acyl FB 1, N-fatty acyl FB 1 and N-palmitoyl-HFB 1. HFB 1, pHFB 1, NCM-FB 1 and NDF-FB 1 show a similar toxicological profile but are less potent than FB 1. Although in vitro data shows that N-fatty acyl FBs are more toxic in vitro than FB 1, no in vivo data were available for N-fatty acyl FBs and O-fatty acyl FBs. The CONTAM Panel concluded that it was not appropriate to include modified FBs in the group TDI for FB 1-4. The uncertainty associated with the present assessment is high, but could be reduced provided more data are made available on occurrence, toxicokinetics and toxicity of FB 2-6 and modified forms of FB 1-4.

The microbial ecology of wine grape berries

Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with different physiological characteristics and effects upon wine production. Some species are only found in grapes, such as parasitic fungi and environmental bacteria, while others have the ability to survive and grow in wines, constituting the wine microbial consortium. This consortium covers yeast species, lactic acid bacteria and acetic acid bacteria. The proportion of these microorganisms depends on the grape ripening stage and on the availability of nutrients. Grape berries are susceptible to fungal parasites until véraison after which the microbiota of truly intact berries is similar to that of plant leaves, which is dominated by basidiomycetous yeasts (e.g. Cryptococcus spp., Rhodotorula spp. Sporobolomyces spp.) and the yeast-like fungus Aureobasidium pullulans. The cuticle of visually intact berries may bear microfissures and softens with ripening, increasing nutrient availability and explaining the possible dominance by the oxidative or weakly fermentative ascomycetous populations (e.g. Candida spp., Hanseniaspora spp., Metschnikowia spp., Pichia spp.) approaching harvest time. When grape skin is clearly damaged, the availability of high sugar concentrations on the berry surface favours the increase of ascomycetes with higher fermentative activity like Pichia spp. and Zygoascus hellenicus, including dangerous wine spoilage yeasts (e.g. Zygosaccharomyces spp., Torulaspora spp.), and of acetic acid bacteria (e.g. Gluconobacter spp., Acetobacter spp.). The sugar fermenting species Saccharomyces cerevisiae is rarely found on unblemished berries, being favoured by grape damage. Lactic acid bacteria are minor partners of grape microbiota and while being the typical agent of malolactic fermentation, Oenococcus oeni has been seldom isolated from grapes in the vineyard. Environmental ubiquitous bacteria of the genus Enterobacter spp., Enterococcus spp., Bacillus spp., Burkholderia spp., Serratia spp., Staphylococcus spp., among others, have been isolated from grapes but do not have the ability to grow in wines. Saprophytic moulds, like Botrytis cinerea, causing grey rot, or Aspergillus spp., possibly producing ochratoxin, are only active in the vineyard, although their metabolites may affect wine quality during grape processing. The impact of damaged grapes in yeast ecology has been underestimated mostly because of inaccurate grape sampling. Injured berries hidden in apparently sound bunches explain the recovery of a higher number of species when whole bunches are picked. Grape health status is the main factor affecting the microbial ecology of grapes, increasing both microbial numbers and species diversity. Therefore, the influence of abiotic (e.g. climate, rain, hail), biotic (e.g. insects, birds, phytopathogenic and saprophytic moulds) and viticultural (e.g. fungicides) factors is dependent on their primary damaging effect.