Investigations on the occurrence of mycotoxins in beer

Highlights

• Ergot alkaloids, alternariol, deoxynivalenol, and zearalenone were surveyed in beer.

• All toxins were detected with high frequency, but in most cases at low levels.

• Highest concentrations up to 20 μg/L were detected for deoxynivalenol.

• Beer is not a key source of intake of ergot alkaloids and alternariol.

• Further studies are requested to investigate the presence of these toxins in beer.

Abstract

The occurrence of several mycotoxins, including ergot alkaloids, alternariol (AOH), deoxynivalenol (DON), and zearalenone (ZEA) in beer (n = 44) from the German market was studied by using enzyme immunoassay methods. Detection limits in beer were 2.1 μg/L (DON), 0.14 μg/L (ZEA), 0.06 μg/L (ergometrine equivalents), and 0.18 μg/L (AOH). DON was detected in 75% of the samples (2.2–20 μg/L, median 3.7 μg/L). All samples were positive for ZEA (0.35–2.0 μg/L, median 0.88 μg/L) and AOH (0.23–1.6 μg/L, median 0.45 μg/L). Most samples (93%) were positive for ergot alkaloids (0.07–0.47 μg/L, median 0.15 μg/L). Correlating toxin levels in beer with European Union tolerable daily intake (TDI) levels for DON (1 μg/kg b.w.), ZEA (0.25 μg/kg b.w.), and ergot alkaloids (0.6 μg/kg b.w.), beer does not represent a major source of intake of these toxins. No TDI data are available for AOH, but considering toxin levels in other foods, beer does not seem to be a major source of intake of this toxin either. Nevertheless, the frequency of their occurrence warrants further study of ergot alkaloids and AOH in raw materials used for beer brewing.

Introduction

Beer is the most consumed alcoholic beverage in the EU (WHO, 2014). In 2013, the average per capita consumption was 71 L in Europe. In some countries, annual consumption is more than 100 L (The Brewers of Europe, 2014). Therefore, the dietary exposure to natural toxins via beer might be of relevance for a high percentage of consumers in Europe.

Traditional raw materials for beer production are barley and wheat. These grains have often been associated with contamination of mycotoxins (Pereira, Fernandes, & Cunha, 2014). In a former review on mycotoxin carry-over from contaminated grains into beer, it has been suggested that existent mycotoxin levels in the raw grain might further increase as a result of promoted fungal growth in the malting process (Scott, 1996). According to previous reports on their moderate stability during food processing (Bullerman and Bianchini, 2007, Milani and Maleki, 2014), mycotoxins may, to some extent, effectively overcome the brewing process and thus be transferred from malt into beer. Therefore, the presence of mycotoxins in beer potentially is a significant source of intake. Research in this field has mainly been focused on the Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEA), which are known to frequently contaminate brewing grains (Barthel et al., 2012; Běláková et al., 2014, SCOOP, 2003). The occurrence of these mycotoxins in beer has been examined in several studies (Curtui et al., 2005, Kappenstein et al., 2005, Kuzdraliński et al., 2013, Samar and Resnik, 2002). Since their potential to cause serious health problems in animals and humans has been well documented (Escrivá et al., 2015, Richard, 2007), the European Commission has established a range of maximum limits for DON and ZEA in cereals and cereal-based foods in order to prevent human mycotoxicoses in consequence of consumption of contaminated foodstuffs (EC, 2006). Maximum amounts for these mycotoxins in beer have not specifically been set so far.

Other groups of mycotoxins such as ergot alkaloids and Alternaria toxins have also been related with detrimental effects according to intake of contaminated foods (Asam and Rychlik, 2013, Crews et al., 2009, Dong et al., 1987). Ergot alkaloids, mainly produced by the fungus Claviceps purpurea, have been known since the Middle Ages to cause intoxications in humans and animals, described as ergotism, which is characterized by a variety of symptoms ranging from abdominal pain, vomiting, and neurological signs to the point of severe vasoconstrictive effects (Krska & Crews, 2008). Otherwise, some ergot alkaloids also play an important role as pharmaceuticals for treatment of vascular and neurological diseases, including migraine, thrombosis, and parkinsonism (Flieger, Wurst, & Shelby, 1997).

Relating to Alternaria toxins, toxicity data are rather sparsely available; to date some of these mycotoxins have been shown to be teratogenic in vivo (EFSA, 2011b). Moreover, genotoxic effects of alternariol (AOH) and alternariol monomethyl ether (AME) in vitro have been described (EFSA, 2011b). In addition, these toxins have been associated with human esophageal cancer in the context of contaminated grain in Linxian, China (Ostry, 2008).

In the EU, regulatory levels for ergot alkaloids and Alternaria toxins in food have not yet been defined. Recently, a maximum level of 0.5 g/kg ergot sclerotia in certain unprocessed cereals has been set by Commission Regulation (EU) 2015/1940 of October 2015 (EC, 2015). Although this regulation does not directly refer to the ergot alkaloid content, it characterizes ergot as a topic of concern, which should forward the provision of maximum levels for ergot alkaloids in the near future. In 2012, the European Commission has recommended that member states should collect data on the predominantly occurring ergot alkaloids in food and feed, namely ergometrine, ergotamine, ergosine, ergocristine, ergocryptine, ergocornine, and their related -inines (EC, 2012). In previous studies, both ergot alkaloids and Alternaria toxins have been detected in grains and grain-based foods intended for human consumption (Crews et al., 2009, Müller and Korn, 2013, Scott et al., 2012). In barley, the occurrence of these mycotoxins has already been demonstrated (Liesener et al., 2010, Medina et al., 2006). Medina et al. (2006), in particular, identified Alternaria as the dominant fungal species isolated from malting barley samples. Still, relatively few information is available about the occurrence of these mycotoxins in beer. Recently, Prelle, Spadaro, Garibaldi, and Gullino (2013) found AOH to be the most frequent occurring Alternaria mycotoxin in beer. In addition, low average amounts of tenuazonic acid (TEA) in beer had been reported before (Siegel, Merkel, Koch, & Nehls, 2010).

Regarding ergot alkaloids, the fate of these mycotoxins throughout the brewing process was studied by Schwarz, Hill, and Rottinghaus (2007) in the scope of a micro-brewing experiment with barley and wheat samples containing ergot sclerotia. The authors recorded low quantities of ergot alkaloids transmitted into beer.

To the best of our knowledge, a survey of ergot alkaloids and AOH in commercial beer samples from the German market has not yet been published. We therefore performed a preliminary survey of mycotoxins belonging to four different groups, namely DON, ZEA as well as ergot alkaloids and AOH using competitive enzyme immunoassays (EIA) as rapid screening methods.