Alexander Mauch

Fundamental study on the influence of Fusarium infection on quality and ultrastructure of barley malt

Barley infection with Fusarium species has been a long standing problem for the malting and brewing industries. In this study, we evaluate the impact of Fusarium culmorum infected raw barley on the final malt quality. Barley grains were infected for 5 days at optimum fungal growth conditions. Grains were fully characterized and compared to standard barley grains. Due to fungal infection, germinative energy of infected barley grains decreased by 45%; its water sensitivity increased dramatically, and grains accumulated 199 μg/kg of deoxynivalenol (DON). Barley grains were subsequently malted for 8 days, fully characterized and compared to standard malt grains. Fungal growth behavior was evaluated during malting using a PCR-based assay and mycotoxins were measured using HPLC. Fungal biomass increased in grains, during all stages of malting. Infected malt accumulated 8-times its DON concentration during malting. Kernel ultrastructure was evaluated using scanning electron and confocal laser scanning microscopy. Infected malt grains were characterized by extreme structural proteolytic, (hemi)-cellulolytic and starch deterioration with increased friability and fragmentation. Infected grains had higher protease and β-glucanase activities, lower amylase activity, a greater proportion of free amino and soluble nitrogen, and a lower β-glucan content. Malt loss was over 27% higher in infected malt in comparison to the control. The results of this study revealed that 20% F. culmorum infected barley kernels lead to a significant reduction in malt quality as well as mycotoxin formation.

The use of Lactobacillus brevis PS1 to in vitro inhibit the outgrowth of Fusarium culmorum and other common Fusarium species found on barley.

A total of 129 lactic acid bacteria (LAB) were screened for antifungal activity against common Fusarium spp. isolated from brewing barley. Four out of the five most inhibiting isolates were identified as Lactobacillus brevis, whereas one belonged to Weissella cibaria. L. brevis PS1, the isolate showing the largest inhibition spectrum, was selected and the influence of its freeze-dried cell-free supernatant (cfsP) on germination of macroconidia as well as mycelia growth was investigated using Fusarium culmorum as target organism.Addition of cfsP into the growth medium at concentrations > or = 2% altered the growth morphology of F.culmorum, whereas at concentrations > 5% the outgrowth of germ tubes from macroconidia was delayed and distorted. The presence of 10% cfsP completely inhibited the outgrowth of F. culmorum macroconidia. The activity of the compounds produced by L. brevis PS1 was higher at low pH values, i.e. pH < 5. Heating and/or proteolytic treatment reduced the inhibitory activity of cfsP, indicating that L. brevis produces organic acids and proteinaceous compounds which are active against Fusarium spp.

Lactic Acid Bacteria as a Cell Factory for the Delivery of Functional Biomolecules and Ingredients in Cereal-Based Beverages: A Review

In this review, we aim to describe the mechanisms by which LAB can fulfil the novel role of efficient cell factory for the production of functional biomolecules and food ingredients to enhance the quality of cereal-based beverages. LAB fermentation is a safe, economical, and traditional method of food preservation foremost, as well as having the additional benefits of flavor, texture, and nutrition amelioration. Additionally, LAB fermentation in known to render cereal-based foods and beverages safe, in a chemical-free, consumer-friendly manner, from an antinutrient and toxigenic perspective. Huge market opportunities and potential exist for food manufacturers who can provide the ideal functional beverage fulfilling consumer needs. Newly developed fermented cereal-based beverages must address markets globally including, high-nutrition markets (developing countries), lifestyle choice consumers (vegetarian, vegan, low-fat, low-salt, low-calorie), food-related non-communicable disease sufferers (cardiovascular disease, diabetes), and green label consumers (Western countries). To fulfil these recommendations, a suitable LAB starter culture and cereal-based raw materials must be developed. These strains would be suitable for the biopreservation of cereal beverages and, ideally, would be highly antifungal, anti-mycotoxigenic, mycotoxin-binding and proteolytic (neutralize toxic peptides and release flavor-contributing amino acids) with an ability to ferment cereals, whilst synthesizing oligosaccharides, thus presenting a major opportunity for the development of safe cereal-based prebiotic functional beverages to compete with and replace the existing dairy versions.

Barley malt wort fermentation by exopolysaccharide- forming Weissella cibaria MG1 for the production of a novel beverage

The growing interest of governments and industry in developing healthy and natural alternative foods and beverages that will fulfil the consumer drive towards a healthy lifestyle and clean‐label, natural diet has led to an increase in traditional lactic acid bacteria fermentation research. In particular, this research aims to address the organoleptic modulation of beverages using in situ‐produced bacterial polysaccharides.

Inhibition of growth of Trichophyton tonsurans by Lactobacillus reuteri

Aim:  The aims of this study were to identify antifungal lactic acid bacteria (LAB) and characterize their activity against the dermatophyte Trichophyton tonsurans.