Mycotoxins and beer. Impact of beer production process on mycotoxin contamination. A review

Abstract

Beer is the most consumed alcoholic beverage in the world. Its contamination with mycotoxins is of public health concern, especially for heavy drinkers. Beer production implies a variety of operations which might impact the initial level of mycotoxins in a positive or negative way. The complexity of these operations do not give to the brewer a complete control on chemical and biochemical reactions that take place in the batch, but the knowledge about mycotoxin properties can help in identifying the operations decreasing their level in foodstuffs and in the development of mitigation strategies. This review discusses available data about mycotoxin evolution during malting and brewing process. The operations that may lead to a decrease in mycotoxin load are found to be steeping, kilning, roasting, fermentation and stabilization operations applied over the process (e.g. clarification). Also, other general decontamination strategies usually employed in food industry, such as hot water treatment of barley, ozonation or even the use of lactic acid bacteria starter cultures during malting or fermentation are considered.

Ochratoxin A in Beers Marketed in Portugal: Occurrence and Human Risk Assessment

“…Drying (kilning) conditions are unfavorable for fungi (especially the first phase with a temperature of 50 • C and grain moisture of 45%). Knowing that the intensity of kilning and roasting (if applied) is crucial in malt flavor and color formation [33], fungi are removed during this process but thermostable mycotoxins produced before kilning persist [35]. Nowadays, the largest percentage of malt in most beers is pale malt which is only mildly dried at moderate temperature and might explain our results.…”

“…The procedures involved in beer production use maximum operation temperatures lower than those able to destroy mycotoxins. However, they may impact mycotoxin levels given the physical, chemical, and biochemical alterations that take place [33]. The presence of OTA has been associated with barley malt contamination with ochratoxigenic species, namely Penicillium verrucosum.…”

“…During these phases, mycotoxins may be removed through the drainage water, with the spent grains or with the fermentation residue. Moreover, they can also be diluted or destroyed as a result of the thermic treatment [33].…”

Transfer of Fusarium mycotoxins from malt to boiled wort

“…Mashing consists 63 of mixing coarse ground malt with a large amount of water (approximately 170 g per litre) 64 under specific temperatures to activate all the enzymes present in malt, namely: 45-50 ºC is 65 set to ensure protein hydrolysis, 60-65 ºC lead to maltose production, and 75-78 ºC activate 66 -amylases (Kunze, 2006). Then, malt grist is removed from the wort and after adjusting the 67 relative density of the wort with water (final density should vary between 1005 and 1010 68 kg/m 3 ) boiling starts, lasting from 45-60 min up to 3h depending on the beer style to be 69 obtained (Pascari et al, 2018). 70…”

“…According to previously published studies, a transfer of mycotoxins from raw materials to 80 beer is possible due to their relatively high resistance to physical treatments applied during 81 brewing (Inoue, Nagatomi, Uyama, & Mochizuki, 2013; Pascari et al, 2018). Nevertheless, 82 several stages of the production scheme are proved to decrease the initial mycotoxin 83 contamination levels (Lancova et al, 2008).…”