Arja Laitila - Academia.edu (original) (raw)

Papers by Arja Laitila

Research paper thumbnail of TaqMan qPCR for Quantification of Clonostachys rosea Used as a Biological Control Agent Against Fusarium graminearum

Frontiers in Microbiology

Research paper thumbnail of Dextran produced in situ as a tool to improve the quality of wheat-faba bean composite bread

Food Hydrocolloids

The incorporation of faba bean flour into wheat-based products is a sustainable way to obtain pro... more The incorporation of faba bean flour into wheat-based products is a sustainable way to obtain proteinenriched food items. However, developing breads with a higher content of faba bean flour is challenging due to the poor textural/sensory properties of the final product. A potential solution is to use hydrocolloids as structuring agents to increase the viscoelastic properties of the composite bread. Microbial dextran is a natural hydrocolloid which can be used as a bread texture improver either as a pure food ingredient or by in situ production during sourdough fermentation. The aim of this study was to compare the influence of dextran produced in situ by Weissella confusa VTT E-143403 (E3403) and Leuconostoc pseudomesenteroides DSM 20193 in faba bean sourdoughs on the quality of wheat bread supplemented with 43% faba bean sourdough. The impact of dextran on the rheological properties of dough and textural properties of the final bread were evaluated. Dextran formed by W. confusa and L. pseudomesenteroides reached a level of 5.2 and 3.6% (flour basis), respectively. Incorporation of faba bean sourdough containing dextran synthesized by W. confusa improved the dough viscoelastic properties, and also increased the specific volume (~21%) and reduced crumb hardness (~12%) of the final bread, compared to control breads. Similar positive effects were not obtained with sourdough containing dextran from L. pseudomesenteroides, probably due to its higher acidity. Dextran synthesized in situ by W. confusa is a promising clean label hydrocolloid option to improve the quality of wheat bread enriched with faba bean flour.

Research paper thumbnail of Impact of in situ produced exopolysaccharides on rheology and texture of fava bean protein concentrate

Food Research International

The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) ... more The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) on the rheological and textural properties of fava bean protein concentrate (FPC). EPS (dextrans) were produced from sucrose by two lactic acid bacteria (LAB). The acidification, rheology, and texture of FPC pastes fermented with Leuconostoc pseudomesenteroides DSM 20193 and Weissella confusa VTT E-143403 (E3403) were compared. A clear improvement in rheological and textural parameters was observed in sucrose-added pastes after fermentation, especially with W. confusa VTT E3403. Only moderate proteolysis of fava bean protein during fermentation was observed. The microstructure of the protein in FPC pastes, as observed by confocal laser scanning microscopy, revealed a less continuous and denser structure in EPS-abundant pastes. The beneficial structure formed during EPS-producing fermentation could not be mimicked by simply mixing FPC, isolated dextran, lactic acid, and acetic acid with water. These results emphasize the benefits of in situ produced EPS in connection with the LAB fermentation of legume protein-rich foods. Fermentation with EPS-producing LAB is a cost-effective and clean-labeled technology to obtain tailored textures, and it can further enhance the usability of legumes in novel foods.

Research paper thumbnail of Acidipropionibacterium virtanenii sp. nov., isolated from malted barley

International journal of systematic and evolutionary microbiology, 2018

A Gram-stain-positive, catalase-positive and pleomorphic rod organism was isolated from malted ba... more A Gram-stain-positive, catalase-positive and pleomorphic rod organism was isolated from malted barley in Finland, classified initially by partial 16S rRNA gene sequencing and originally deposited in the VTT Culture Collection as a strain of Propionibacterium acidipropionici (currently Acidipropionibacterium acidipropionici). The subsequent comparison of the whole 16S rRNA gene with other representatives of the genus Acidipropionibacterium revealed that the strain belongs to a novel species, most closely related to Acidipropionibacterium microaerophilum and Acidipropionibacterium acidipropionici, with similarity values of 98.46 and 98.31 %, respectively. The whole genome sequencing using PacBio RS II platform allowed further comparison of the genome with all of the other DNA sequences available for the type strains of the Acidipropionibacterium species. Those comparisons revealed the highest similarity of strain JS278 to A. acidipropionici, which was confirmed by the average nucleoti...

Research paper thumbnail of Characterisation of barley-associated bacteria and their impact on wort separation performance

Journal of the Institute of Brewing

Wort separation is one of the rate-limiting steps in the brewhouse. It is a complex process, infl... more Wort separation is one of the rate-limiting steps in the brewhouse. It is a complex process, influenced by barley components such as proteins, β-glucans, residual starch and lipids. Filtration performance may also be influenced by microbial biofilms forming on the outer layers of the grains. This study aimed to identify the main barley-associated bacteria influencing wort separation efficiency. Next-generation sequencing was applied to characterise indigenous bacterial communities associated with Overture barley from different geographical locations as well as the bacterial population dynamics during laboratory-scale malting. In order to study the weakened filtration performance potentially caused by induced bacterial biofilm formation, a small portion of barley (5-12%) was subjected to mild husk damage prior to steeping. The bacterial communities were dominated by Gammaproteobacteria, accounting for >70% of the total bacterial population. Bacterial growth induction significantly decreased wort filtration performance. A content of~12% of injured grains decreased the rate of wort separation by up to 25%, with over 10% lower extract yields. This study showed that bacteria associated with barley are one of the key factors influencing wort separation.

Research paper thumbnail of Management of barley-associated bacterial biofilms: a key to improving wort separation

Journal of the Institute of Brewing

Several bacterial groups are associated with poor wort filtration performance. In this study we c... more Several bacterial groups are associated with poor wort filtration performance. In this study we characterized the shifts within the bacterial community during malting by next-generation sequencing. The aim was to reveal the bacterial groups involved in the decreased mash filterability caused by hus-damaged barley. Field emission scanning electron microscopy was used to visualise biofilm formation in the outer layers of barley. This study also investigated the impacts of bacterial biofilm suppression on extract recovery. The bacterial growth was suppressed with antibacterial treatment and modified by adding Lactobacillus plantarum VTT E-78076 (E76) starter cultures to steeping. In particular, barley-associated Leuconostoc was associated with decreased wort filtration performance. This study showed that development of biofilm containing extracellular polymeric substances (EPS) on the kernel surface layers during malting was a crucial factor influencing wort separation. The application of L. plantarum E76 successfully controlled the bacterial community during malting and improved wort filtration. Thus, improved wort separation and higher extract recovery could be obtained by management of barley-associated biofilms during malting.

Research paper thumbnail of The lager yeast Saccharomyces pastorianus removes and transforms Fusarium trichothecene mycotoxins during fermentation of brewer's wort

Food chemistry, Jan 15, 2016

An investigation was conducted to determine the fate of deoxynivalenol, deoxynivalenol-3-glucosid... more An investigation was conducted to determine the fate of deoxynivalenol, deoxynivalenol-3-glucoside, HT-2 toxin and T-2 toxin, during a four-day fermentation with the lager yeast Saccharomyces pastorianus. The influence of excessive mycotoxin concentrations on yeast growth, productivity and viability were also assessed. Mycotoxins were dosed at varying concentrations to 11.5° Plato wort. Analysis of yeast revealed that presence of the toxins even at concentrations up to 10,000μg/L had little or no effect on sugar utilisation, alcohol production, pH, yeast growth or cell viability. Of the dosed toxin amounts 9-34% were removed by the end of fermentation, due to physical binding and/or biotransformation by yeast. Deoxynivalenol-3-glucoside was not reverted to its toxic precursor during fermentation. Processing of full-scan liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS) data with MetaboLynx™ and subsequent LC-QTOF-MS/MS measurements resulted in annotation...

Research paper thumbnail of Bioprocessing of bran for improved functionality

Final HEALTHGRAIN Conference Enhancing Health Benefits of Cereal Foods - Results, Perspectives an... more Final HEALTHGRAIN Conference Enhancing Health Benefits of Cereal Foods - Results, Perspectives and Challenges. Lund, Sweden, 5 - 7 May 2010, 32

Research paper thumbnail of Prediction of barley and Fusarium activities during malting using transcriptional profiling

32nd EBC Congress. Hamburg, Germany, 10 - 14 May 2009

Research paper thumbnail of Prediction of Fusarium activities in malting using transcriptional profiling

Bioforsk FOKUS Vol.5 Nr.7, 28 Nordic Baltic Fusarium Seminar (NBFS). Ski, Norway, 23-25 Nov. 2010

Research paper thumbnail of Fungal hydrophobins as a beer gushing factor - current knowledge and future aspects

32nd EBC Congress. Hamburg, Germany, 10 - 14 May 2009

Research paper thumbnail of Elintarvike- ja juomateollisuuden varautuminen ilmaston muuttumiseen

ABSTRACT Mallas ja Olut Nr.4/2010, 134-139

Research paper thumbnail of Culture-independent PCR-DHPLC technique for profiling of microbial communities in malting and brewing process

Research paper thumbnail of Suomen elintarviketuotannon turvallisuuden haasteita muuttuvissa ilmasto-olosuhteissa

Research paper thumbnail of Pichia anomala in malting

First International Pichia anomala mini-Symposium. Uppsala, Sweden, 10 - 12 Feb. 2010, 17

Research paper thumbnail of Mycotoxin production of Fusarium langsethiae and Fusarium sporotrichioides on cereal-based substrates

Mycotoxin Research, 2011

The present study investigated and compared the mycotoxin production of two Fusarium species, F. ... more The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cerealflour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cerealbased assays but was more predominant on the carbohydraterich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000 μg/kg after 7 days' incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.

Research paper thumbnail of Indigenous Microbial Community of Barley Greatly Influences Grain Germination and Malt Quality

Journal of the Institute of Brewing, 2007

The present study was carried out to investigate the impacts of bacterial and fungal communities ... more The present study was carried out to investigate the impacts of bacterial and fungal communities on grain germination and on the malting properties of good-quality two-row barley. In order to suppress the growth of bacterial and/or fungal communities, various antibiotics were added to the first steeping water of barley. This study was also designed to explore the dynamics of the bacterial community in the malting process after antimicrobial treatments by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The diverse microbial community played an active role in the malting ecosystem. Even previously undescribed bacterial species were found in the malting ecosystem. Suppression of the bacterial community mainly consisting of Gram-negative bacteria was advantageous with respect to grain germination and wort separation. In addition, more extract was obtained after antibacterial treatments. The fungal community significantly contributed to the production of microbial β-glucanases and xylanases, and was also involved in proteolysis. An improved understanding of the complex microbial community and its role in malting enables a more controlled process management and the production of high quality malt with tailored properties.

Research paper thumbnail of Yeasts isolated from industrial maltings can suppress Fusarium growth and formation of gushing factors

Journal of Industrial Microbiology & Biotechnology, 2007

Fusarium infection of barley and malt can cause severe problems in the malting and brewing indust... more Fusarium infection of barley and malt can cause severe problems in the malting and brewing industry. In addition to being potential mycotoxin producers, Fusarium fungi are known to cause beer gushing (spontaneous overfoaming of beer). Cereal-derived bacteria and yeasts are potential biocontrol agents. In this study, the antifungal potential of selected yeasts (12 strains) derived from the industrial malting ecosystem was studied in vitro with a plate-screening assay. Several ascomycetous yeast strains showed antagonistic activity against Weld and storage moulds, Pichia anomala being the most eVective strain. The eVects of P. anomala VTT C-04565 (C565) were examined in laboratory scale malting with naturally contaminated barley exhibiting gushing potential. P. anomala C565 restricted Fusarium growth and hydrophobin production during malting and prevented beer gushing. Grain germination was not disturbed by the presence of yeast. Addition of P. anomala C565 into the steeping seemed to retard wort Wltration, but the Wltration performance was recovered when yeast culture was combined with Lactobacillus plantarum VTT E-78076. Well-characterized microbial cultures could be used as food-grade biocontrol agents and they oVer a natural tool for tailoring of malt properties.

Research paper thumbnail of Antifungal activities of two Lactobacillus plantarum strains against Fusarium moulds in vitro and in malting of barley

Journal of Applied Microbiology, 2002

Aims: The Lactobacillus plantarum strains VTT E-78076 (E76) and VTT E-79098 (E98) were studied fo... more Aims: The Lactobacillus plantarum strains VTT E-78076 (E76) and VTT E-79098 (E98) were studied for their antifungal potential against Fusarium species. Methods and Results: In vitro screening with automated turbidometry as well as direct and indirect impedimetric methods clearly showed Lact. plantarum cell-free extracts to be effective against Fusarium species including Fusarium avenaceum, F. culmorum, F. graminearum and F. oxysporum. However, great variation in growth inhibition was observed between different Fusarium species and even between strains. The antifungal potential of Lact. plantarum E76 culture, including cells and spent medium, was also examined in laboratory-scale malting with naturally contaminated two-rowed barley from the crops of 1990-96. The growth of the indigenous Fusarium flora was restricted by the addition of Lact. plantarum E76 to the steeping water. However, the antifungal effect was greatly dependent on the contamination level and the fungal species ⁄ strains present on barley in different years. Conclusions: Lactobacillus plantarum strains E76 and E98 had a fungistatic effect against different plant pathogenic, toxigenic and gushing-active Fusarium fungi. Significance and Impact of the Study: The present study indicates that Lact. plantarum strains with known and selected characteristics could be used as a natural, food-grade biocontrol agent for management of problems caused by Fusarium fungi during germination of cereals.

Research paper thumbnail of Oxygen Deficiency in Barley ( Hordeum vulgare ) Grain during Malting

Journal of Agricultural and Food Chemistry, 2006

The steep water is generally aerated in industrial barley malting. However, it is questionable wh... more The steep water is generally aerated in industrial barley malting. However, it is questionable whether oxygen actually reaches the embryo, which remains entrapped under the husk, testa, and pericarp until chitting occurs. The aim of our study was to investigate whether barley embryos experience oxygen deficiency during steeping, and whether various steeping conditions affect the oxygen deficiency. Alcohol dehydrogenase Adh2 was induced in all steeping conditions studied. Therefore, oxygen deficiency occurred regardless of the steeping conditions. However, steeping conditions affected the rate of recovery from oxygen deficiency, germination rate, and onset of alpha-amylase production. When barley was subjected to oxygen deficiency by applying N(2) gas during steeping, the timing of the treatment determined its effects. The importance of aeration increased as the process proceeded. Oxygen deprivation at the beginning of the process had little effect on malt quality. Therefore, the timing of aeration is important in the optimization of germination during the steeping stage of malting.

Research paper thumbnail of TaqMan qPCR for Quantification of Clonostachys rosea Used as a Biological Control Agent Against Fusarium graminearum

Frontiers in Microbiology

Research paper thumbnail of Dextran produced in situ as a tool to improve the quality of wheat-faba bean composite bread

Food Hydrocolloids

The incorporation of faba bean flour into wheat-based products is a sustainable way to obtain pro... more The incorporation of faba bean flour into wheat-based products is a sustainable way to obtain proteinenriched food items. However, developing breads with a higher content of faba bean flour is challenging due to the poor textural/sensory properties of the final product. A potential solution is to use hydrocolloids as structuring agents to increase the viscoelastic properties of the composite bread. Microbial dextran is a natural hydrocolloid which can be used as a bread texture improver either as a pure food ingredient or by in situ production during sourdough fermentation. The aim of this study was to compare the influence of dextran produced in situ by Weissella confusa VTT E-143403 (E3403) and Leuconostoc pseudomesenteroides DSM 20193 in faba bean sourdoughs on the quality of wheat bread supplemented with 43% faba bean sourdough. The impact of dextran on the rheological properties of dough and textural properties of the final bread were evaluated. Dextran formed by W. confusa and L. pseudomesenteroides reached a level of 5.2 and 3.6% (flour basis), respectively. Incorporation of faba bean sourdough containing dextran synthesized by W. confusa improved the dough viscoelastic properties, and also increased the specific volume (~21%) and reduced crumb hardness (~12%) of the final bread, compared to control breads. Similar positive effects were not obtained with sourdough containing dextran from L. pseudomesenteroides, probably due to its higher acidity. Dextran synthesized in situ by W. confusa is a promising clean label hydrocolloid option to improve the quality of wheat bread enriched with faba bean flour.

Research paper thumbnail of Impact of in situ produced exopolysaccharides on rheology and texture of fava bean protein concentrate

Food Research International

The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) ... more The aim of this study was to investigate the impact of in situ produced exopolysaccharides (EPS) on the rheological and textural properties of fava bean protein concentrate (FPC). EPS (dextrans) were produced from sucrose by two lactic acid bacteria (LAB). The acidification, rheology, and texture of FPC pastes fermented with Leuconostoc pseudomesenteroides DSM 20193 and Weissella confusa VTT E-143403 (E3403) were compared. A clear improvement in rheological and textural parameters was observed in sucrose-added pastes after fermentation, especially with W. confusa VTT E3403. Only moderate proteolysis of fava bean protein during fermentation was observed. The microstructure of the protein in FPC pastes, as observed by confocal laser scanning microscopy, revealed a less continuous and denser structure in EPS-abundant pastes. The beneficial structure formed during EPS-producing fermentation could not be mimicked by simply mixing FPC, isolated dextran, lactic acid, and acetic acid with water. These results emphasize the benefits of in situ produced EPS in connection with the LAB fermentation of legume protein-rich foods. Fermentation with EPS-producing LAB is a cost-effective and clean-labeled technology to obtain tailored textures, and it can further enhance the usability of legumes in novel foods.

Research paper thumbnail of Acidipropionibacterium virtanenii sp. nov., isolated from malted barley

International journal of systematic and evolutionary microbiology, 2018

A Gram-stain-positive, catalase-positive and pleomorphic rod organism was isolated from malted ba... more A Gram-stain-positive, catalase-positive and pleomorphic rod organism was isolated from malted barley in Finland, classified initially by partial 16S rRNA gene sequencing and originally deposited in the VTT Culture Collection as a strain of Propionibacterium acidipropionici (currently Acidipropionibacterium acidipropionici). The subsequent comparison of the whole 16S rRNA gene with other representatives of the genus Acidipropionibacterium revealed that the strain belongs to a novel species, most closely related to Acidipropionibacterium microaerophilum and Acidipropionibacterium acidipropionici, with similarity values of 98.46 and 98.31 %, respectively. The whole genome sequencing using PacBio RS II platform allowed further comparison of the genome with all of the other DNA sequences available for the type strains of the Acidipropionibacterium species. Those comparisons revealed the highest similarity of strain JS278 to A. acidipropionici, which was confirmed by the average nucleoti...

Research paper thumbnail of Characterisation of barley-associated bacteria and their impact on wort separation performance

Journal of the Institute of Brewing

Wort separation is one of the rate-limiting steps in the brewhouse. It is a complex process, infl... more Wort separation is one of the rate-limiting steps in the brewhouse. It is a complex process, influenced by barley components such as proteins, β-glucans, residual starch and lipids. Filtration performance may also be influenced by microbial biofilms forming on the outer layers of the grains. This study aimed to identify the main barley-associated bacteria influencing wort separation efficiency. Next-generation sequencing was applied to characterise indigenous bacterial communities associated with Overture barley from different geographical locations as well as the bacterial population dynamics during laboratory-scale malting. In order to study the weakened filtration performance potentially caused by induced bacterial biofilm formation, a small portion of barley (5-12%) was subjected to mild husk damage prior to steeping. The bacterial communities were dominated by Gammaproteobacteria, accounting for >70% of the total bacterial population. Bacterial growth induction significantly decreased wort filtration performance. A content of~12% of injured grains decreased the rate of wort separation by up to 25%, with over 10% lower extract yields. This study showed that bacteria associated with barley are one of the key factors influencing wort separation.

Research paper thumbnail of Management of barley-associated bacterial biofilms: a key to improving wort separation

Journal of the Institute of Brewing

Several bacterial groups are associated with poor wort filtration performance. In this study we c... more Several bacterial groups are associated with poor wort filtration performance. In this study we characterized the shifts within the bacterial community during malting by next-generation sequencing. The aim was to reveal the bacterial groups involved in the decreased mash filterability caused by hus-damaged barley. Field emission scanning electron microscopy was used to visualise biofilm formation in the outer layers of barley. This study also investigated the impacts of bacterial biofilm suppression on extract recovery. The bacterial growth was suppressed with antibacterial treatment and modified by adding Lactobacillus plantarum VTT E-78076 (E76) starter cultures to steeping. In particular, barley-associated Leuconostoc was associated with decreased wort filtration performance. This study showed that development of biofilm containing extracellular polymeric substances (EPS) on the kernel surface layers during malting was a crucial factor influencing wort separation. The application of L. plantarum E76 successfully controlled the bacterial community during malting and improved wort filtration. Thus, improved wort separation and higher extract recovery could be obtained by management of barley-associated biofilms during malting.

Research paper thumbnail of The lager yeast Saccharomyces pastorianus removes and transforms Fusarium trichothecene mycotoxins during fermentation of brewer's wort

Food chemistry, Jan 15, 2016

An investigation was conducted to determine the fate of deoxynivalenol, deoxynivalenol-3-glucosid... more An investigation was conducted to determine the fate of deoxynivalenol, deoxynivalenol-3-glucoside, HT-2 toxin and T-2 toxin, during a four-day fermentation with the lager yeast Saccharomyces pastorianus. The influence of excessive mycotoxin concentrations on yeast growth, productivity and viability were also assessed. Mycotoxins were dosed at varying concentrations to 11.5° Plato wort. Analysis of yeast revealed that presence of the toxins even at concentrations up to 10,000μg/L had little or no effect on sugar utilisation, alcohol production, pH, yeast growth or cell viability. Of the dosed toxin amounts 9-34% were removed by the end of fermentation, due to physical binding and/or biotransformation by yeast. Deoxynivalenol-3-glucoside was not reverted to its toxic precursor during fermentation. Processing of full-scan liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS) data with MetaboLynx™ and subsequent LC-QTOF-MS/MS measurements resulted in annotation...

Research paper thumbnail of Bioprocessing of bran for improved functionality

Final HEALTHGRAIN Conference Enhancing Health Benefits of Cereal Foods - Results, Perspectives an... more Final HEALTHGRAIN Conference Enhancing Health Benefits of Cereal Foods - Results, Perspectives and Challenges. Lund, Sweden, 5 - 7 May 2010, 32

Research paper thumbnail of Prediction of barley and Fusarium activities during malting using transcriptional profiling

32nd EBC Congress. Hamburg, Germany, 10 - 14 May 2009

Research paper thumbnail of Prediction of Fusarium activities in malting using transcriptional profiling

Bioforsk FOKUS Vol.5 Nr.7, 28 Nordic Baltic Fusarium Seminar (NBFS). Ski, Norway, 23-25 Nov. 2010

Research paper thumbnail of Fungal hydrophobins as a beer gushing factor - current knowledge and future aspects

32nd EBC Congress. Hamburg, Germany, 10 - 14 May 2009

Research paper thumbnail of Elintarvike- ja juomateollisuuden varautuminen ilmaston muuttumiseen

ABSTRACT Mallas ja Olut Nr.4/2010, 134-139

Research paper thumbnail of Culture-independent PCR-DHPLC technique for profiling of microbial communities in malting and brewing process

Research paper thumbnail of Suomen elintarviketuotannon turvallisuuden haasteita muuttuvissa ilmasto-olosuhteissa

Research paper thumbnail of Pichia anomala in malting

First International Pichia anomala mini-Symposium. Uppsala, Sweden, 10 - 12 Feb. 2010, 17

Research paper thumbnail of Mycotoxin production of Fusarium langsethiae and Fusarium sporotrichioides on cereal-based substrates

Mycotoxin Research, 2011

The present study investigated and compared the mycotoxin production of two Fusarium species, F. ... more The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cerealflour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cerealbased assays but was more predominant on the carbohydraterich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000 μg/kg after 7 days' incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.

Research paper thumbnail of Indigenous Microbial Community of Barley Greatly Influences Grain Germination and Malt Quality

Journal of the Institute of Brewing, 2007

The present study was carried out to investigate the impacts of bacterial and fungal communities ... more The present study was carried out to investigate the impacts of bacterial and fungal communities on grain germination and on the malting properties of good-quality two-row barley. In order to suppress the growth of bacterial and/or fungal communities, various antibiotics were added to the first steeping water of barley. This study was also designed to explore the dynamics of the bacterial community in the malting process after antimicrobial treatments by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The diverse microbial community played an active role in the malting ecosystem. Even previously undescribed bacterial species were found in the malting ecosystem. Suppression of the bacterial community mainly consisting of Gram-negative bacteria was advantageous with respect to grain germination and wort separation. In addition, more extract was obtained after antibacterial treatments. The fungal community significantly contributed to the production of microbial β-glucanases and xylanases, and was also involved in proteolysis. An improved understanding of the complex microbial community and its role in malting enables a more controlled process management and the production of high quality malt with tailored properties.

Research paper thumbnail of Yeasts isolated from industrial maltings can suppress Fusarium growth and formation of gushing factors

Journal of Industrial Microbiology & Biotechnology, 2007

Fusarium infection of barley and malt can cause severe problems in the malting and brewing indust... more Fusarium infection of barley and malt can cause severe problems in the malting and brewing industry. In addition to being potential mycotoxin producers, Fusarium fungi are known to cause beer gushing (spontaneous overfoaming of beer). Cereal-derived bacteria and yeasts are potential biocontrol agents. In this study, the antifungal potential of selected yeasts (12 strains) derived from the industrial malting ecosystem was studied in vitro with a plate-screening assay. Several ascomycetous yeast strains showed antagonistic activity against Weld and storage moulds, Pichia anomala being the most eVective strain. The eVects of P. anomala VTT C-04565 (C565) were examined in laboratory scale malting with naturally contaminated barley exhibiting gushing potential. P. anomala C565 restricted Fusarium growth and hydrophobin production during malting and prevented beer gushing. Grain germination was not disturbed by the presence of yeast. Addition of P. anomala C565 into the steeping seemed to retard wort Wltration, but the Wltration performance was recovered when yeast culture was combined with Lactobacillus plantarum VTT E-78076. Well-characterized microbial cultures could be used as food-grade biocontrol agents and they oVer a natural tool for tailoring of malt properties.

Research paper thumbnail of Antifungal activities of two Lactobacillus plantarum strains against Fusarium moulds in vitro and in malting of barley

Journal of Applied Microbiology, 2002

Aims: The Lactobacillus plantarum strains VTT E-78076 (E76) and VTT E-79098 (E98) were studied fo... more Aims: The Lactobacillus plantarum strains VTT E-78076 (E76) and VTT E-79098 (E98) were studied for their antifungal potential against Fusarium species. Methods and Results: In vitro screening with automated turbidometry as well as direct and indirect impedimetric methods clearly showed Lact. plantarum cell-free extracts to be effective against Fusarium species including Fusarium avenaceum, F. culmorum, F. graminearum and F. oxysporum. However, great variation in growth inhibition was observed between different Fusarium species and even between strains. The antifungal potential of Lact. plantarum E76 culture, including cells and spent medium, was also examined in laboratory-scale malting with naturally contaminated two-rowed barley from the crops of 1990-96. The growth of the indigenous Fusarium flora was restricted by the addition of Lact. plantarum E76 to the steeping water. However, the antifungal effect was greatly dependent on the contamination level and the fungal species ⁄ strains present on barley in different years. Conclusions: Lactobacillus plantarum strains E76 and E98 had a fungistatic effect against different plant pathogenic, toxigenic and gushing-active Fusarium fungi. Significance and Impact of the Study: The present study indicates that Lact. plantarum strains with known and selected characteristics could be used as a natural, food-grade biocontrol agent for management of problems caused by Fusarium fungi during germination of cereals.

Research paper thumbnail of Oxygen Deficiency in Barley ( Hordeum vulgare ) Grain during Malting

Journal of Agricultural and Food Chemistry, 2006

The steep water is generally aerated in industrial barley malting. However, it is questionable wh... more The steep water is generally aerated in industrial barley malting. However, it is questionable whether oxygen actually reaches the embryo, which remains entrapped under the husk, testa, and pericarp until chitting occurs. The aim of our study was to investigate whether barley embryos experience oxygen deficiency during steeping, and whether various steeping conditions affect the oxygen deficiency. Alcohol dehydrogenase Adh2 was induced in all steeping conditions studied. Therefore, oxygen deficiency occurred regardless of the steeping conditions. However, steeping conditions affected the rate of recovery from oxygen deficiency, germination rate, and onset of alpha-amylase production. When barley was subjected to oxygen deficiency by applying N(2) gas during steeping, the timing of the treatment determined its effects. The importance of aeration increased as the process proceeded. Oxygen deprivation at the beginning of the process had little effect on malt quality. Therefore, the timing of aeration is important in the optimization of germination during the steeping stage of malting.