Effect of Long-Term Storage on Mycobiota of Barley Grain and Malt

Abstract

Contamination of malting barley grain and malt with micromycetes sampled at various periods post-harvest (3rd, 6th, and 9th month of storage) and types of storage (storage silo and floor warehouse) was investigated. Each of these barley grain samples was malted. This article reports on the changes in the fungal microbiome composition and their overall count in barley grain and malt. From the surface-disinfected barley grain samples collected immediately after harvest, there were eight genera isolated, with a predominance of Alternaria. A small increase of isolated microfungi was detected in barley stored in silo for 3 and 6 months (from 142 isolates to 149) and decreased below the number of isolates in barley before storage (133 isolates). Fungal count during storage gradually decreased up to 9 month in barley stored in floor warehouse (from 142 isolates to 84). The initial total count of microscopic fungi in malt before storage was the highest (112 isolates) with 7 genera detected, compared to malts prepared from barley stored for longer time (54 isolates, 7 genera, 9th month of storage). Alternaria was the most abundant and frequent genus. Quantitative representation of the filamentous microscopic fungi was lower compared to yeasts especially in barley and malt prepared from barley stored at third month of storage in both type of storage. Yeasts were identified from all grain samples and malt samples with mass spectrometry. Most attention was given to the widely distributed fungus Penicillium, 79% of strains produced at least one mycotoxin detected under in vitro assays using the TLC method (97% of them produced griseofulvin, 94% CPA, 79% patulin, 14% roquefortin C, and penitrem A was produced by two screening strains under laboratory conditions). It is therefore important to monitor the microflora throughout the production cycle of “barley to beer”.

Evolution of Alternaria toxins during the brewing process and the usability of optical sorting methods to reduce mycotoxin concentrations in beer

“…The genus Alternaria includes ubiquitous filamentous fungi with a saprophytic or (opportunistic) plant pathogenic lifestyle, commonly found in soil or on decaying plant tissues. About 300 species are known to infest a large variety of agricultural crops, as well as causing postharvest spoilage [12][13][14]. The most important crop damaging representatives include: Alternaria alternata (syn.…”

Microscopic fungi of wheat grain in the Polissya zone

“…Micromycetes are potential phytopathogenic agents that can infect plants both during the growing season and during storage of grain and grain fodder, reducing its nutritional value and, under appropriate conditions, accumulating mycotoxins in it (Rozhkova et al, 2017;Felšöciová et al, 2021;Kolomiets et al, 2022).…”

Fungal Diversity in Barley Under Different Storage Conditions

“…Barley is rich in protein, minerals, vitamins, dietary fiber, and other nutrients ( Rashim et al, 2018 ), and for these reasons it has become the fourth largest cereal crop in the world ( Felšöciová et al, 2021 ). The main barley-producing countries are Russia, Canada, Australia, the European Union countries, and North America ( Jansse et al, 2018 ).…”