Mycotoxins stability evaluation during the beer process and fungi isolation with toxigenic and hydrophobic potential in brewing barley.

Author(s)

Karim Cristina Piacentini

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2019-09-27

Examining board members

Benedito Correa; Geovana Dagostim Savi Bortolotto; Kelly Ishida; Liliana de Oliveira Rocha; Carlos Pelleschi Taborda; Elisabete Jose Vicente

• Advisor: Benedito Correa

Abstract

Current beer consumption has been significant with an evident growth trend. For this reason, the quality of beer and the ingredients used in its production are increasingly relevant. A latent concern of the brewing industry is the occurrence of fungi and mycotoxins in grains, which happen due to several factors, such as: improper handling of the raw material, insect infestation, drying method, types of storage structure, as well as the environmental conditions. The Fusarium genus is considered one of the main contaminating fungi in barley, being able to produce mycotoxins such as deoxynivalenol and zearalenone and proteins called hydrophobins. These proteins have been causing gushing in beer, a phenomenon that consists of excessive foaming at the bottle opening. Therefore, the objective of the present study was to evaluate mycobiota, the occurrence of mycotoxins in barley, as well as the stability of these contaminants (mycotoxins). It also aimed to analyze the gushing potential in barley samples. The samples used in the study were from southern Brazil and collected after harvest. Isolation of the fungi was performed by serial dilution and identification by classical morphology and molecular techniques (sequencing and phylogeny). Barley mycotoxin analyzes and stability experiments of these compounds during beer processing were performed by liquid chromatography coupled with mass spectrometry. The gushing tests were performed according to the methodology developed by Carlsberg. The genus Fusarium was the most predominant fungi, with 56.26 % of the isolates classified as belonging to the Fusarium sambucinum species complex, 31.25 % to the Fusarium tricinctum species complex, 8.33 % to the Fusarium fujikuroi species complex and 2 % to species complex of Fusarium incarnatum-equiseti and Fusarium oxysporum . Regarding the presence of DON and ZEA in barley samples, 2016 crop presented contamination of 90.6 % and 87.5 %, respectively. Additionally, in 2015, the samples presented contamination of 94 % for DON and 73.6 % for ZEA. Analyzes during the beer processing stages showed a significant decrease of DON by 71.6 % between the beginning (barley) and the end of the process (beer). In the gushing tests, 9 samples were positive, with levels ranging from 3 to 124 g/bottle. Our results revealed a significant contamination by fungi, mycotoxins and hydrophobins, compared to studies conducted in other countries. For this reason, there is a need for constant monitoring of these grains, in order to mitigate the risks to consumer health and avoid economic losses to the industry. Research on the gushing phenomenon, including gene expression analysis of the hydrophobin gene in Fusarium species isolated from Brazilian barley, as well as quality testing of raw material within the brewing industry, should be further investigated. (AU)

• FAPESP's process: 16/01798-4 - Evaluation of mycotoxins stability during the craft brewing process and fungi isolation with a toxigenic and hydrophobic potential in malting barley
• Grantee: Karim Cristina Piacentini
• Support Opportunities: Scholarships in Brazil - Doctorate