Brian Gibson - Academia.edu (original) (raw)

Papers by Brian Gibson

Journal of the Institute of Brewing, 2011

Journal of the Institute of Brewing, 2013

ABSTRACT A pilot-scale fermentation was performed using SSU1-overexpressing bottom-fermenting yea... more ABSTRACT A pilot-scale fermentation was performed using SSU1-overexpressing bottom-fermenting yeast strains constructed by ‘self-cloning’. In these strains, the gene SSU1, encoding a plasma membrane protein that excretes sulphite, was highly expressed. The rate of fermentation of the two SSU1-overexpressing strains tested showed some reduction during the mid-fermentation phase as compared with the parental strain. These differences, however, did not affect overall fermentation and the final apparent extracts had decreased to a level normally obtained during brewing. The concentration of hydrogen sulphide in the wort remained low during fermentation in the case of the two self-cloning strains compared with the parent. The concentration of 2-mercapto-3-methyl-1-butanol, a sulphur compound that causes an ‘onion-like’ off-flavour, was also reduced in the case of the self-cloning strains, a result confirmed by sensory evaluation of the beer immediately after bottling. Furthermore, with these strains the anti-oxidation potential of bottled beer, as measured by electron spin resonance, was improved and the concentration of trans-2-nonenal in bottled beer after 7 days of accelerated aging at 37°C was decreased. These observations, together with the lower stale flavour score determined by sensory evaluation of bottled beer after a month of aging at 25°C, indicated that the flavour stability of the beer had been successfully improved. Copyright © 2013 The Institute of Brewing & Distilling

Journal of Clinical Pathology, 1991

A combination of biological and non-biological factors has led to the interspecific hybrid yeast ... more A combination of biological and non-biological factors has led to the interspecific hybrid yeast species Saccharomyces pastorianus becoming one of the world's most important industrial organisms. This yeast is used in the production of lager-style beers, the fermentation of which requires very low temperatures compared to other industrial fermentation processes. This group of organisms has benefited from both the whole-genome duplication in its ancestral lineage and the subsequent hybridization event between S. cerevisiae and S. eubayanus, resulting in strong fermentative ability. The hybrid has key traits, such as cold tolerance and good maltose- and maltotriose-utilizing ability, inherited either from the parental species or originating from genetic interactions between the parent genomes. Instability in the nascent allopolyploid hybrid genome may have contributed to rapid evolution of the yeast to tolerate conditions prevalent in the brewing environment. The recent discovery of S. eubayanus has provided new insights into the evolutionary history of S. pastorianus and may offer new opportunities for generating novel industrially-beneficial lager yeast strains. Copyright © 2014 John Wiley & Sons, Ltd.

Yeast (Chichester, England), 2015

Flavours are biologically active molecules of large commercial interest in the food, cosmetics, d... more Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so-called 'bioflavours', which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini-review, we give an overview of bioflavour production in yeasts from the process-engineering perspective. Two specific examples, production of 2-phenylethanol and vanillin, are used to illustrate the process challenges and strategies used.

73rd Annual Meeting of the American Society of Brewing Chemists. Rhode Island, USA, 15-18 June 2010

European Yeast Flavour Workshop. COST Action FA0907 Bioflavour. INSA Toulouse, France. 28-29 Oct.... more European Yeast Flavour Workshop. COST Action FA0907 Bioflavour. INSA Toulouse, France. 28-29 Oct. 2010

International Symposium for Young Scientist and Technologists in Malting, Brewing and Distilling.... more International Symposium for Young Scientist and Technologists in Malting, Brewing and Distilling. Freising-Weihenstephan, Germany, 19-21 May 2010

Journal of the American Society of Brewing Chemists

Diacetyl is normally considered to be an off-flavor in lager beer, and its removal prolongs the o... more Diacetyl is normally considered to be an off-flavor in lager beer, and its removal prolongs the overall brewing process. Here, the effects of fermentation temperature (9, 12, and 15°C), initial wort pH (4.8, 5.1, and 5.3), and wort free amino nitrogen (FAN) content (222, 252, 287, and 366 ppm) on diacetyl formation and removal in lager beer fermentations were studied in order to develop an enhanced model for predicting fermentation progress (alcohol content, biomass, and pH) and diacetyl concentration. The relationships between model coefficients, temperature, pH, and FAN were calculated, and models predicted fermentation and diacetyl profiles with a good fit (overall relative mean square error less than 10.1%). The model was validated, and also applied to a larger-scale fermentation involving a different wort and yeast strain by adjusting model coefficients. The model can be used for predicting diacetyl concentrations and for brewing process parameter optimization in industrial fer...

Journal- Institute of Brewing

Sahti, a strong, unhopped farmhouse beer flavoured with juniper is still actively brewed in rural... more Sahti, a strong, unhopped farmhouse beer flavoured with juniper is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean =

Journal of agricultural and food chemistry, Jan 11, 2015

Two bottles of beer from an about 170-year-old shipwreck (M1 Fö 403.3) near the Åland Islands in ... more Two bottles of beer from an about 170-year-old shipwreck (M1 Fö 403.3) near the Åland Islands in the Baltic Sea were analyzed. Hop components and their degradation compounds showed that the bottles contained two different beers, one more strongly hopped than the other. The hops used contained higher levels of β-acids than modern varieties and were added before the worts were boiled, converting α-acids to iso-α-acids and β-acids to hulupones. High levels of organic acids, carbonyl compounds, and glucose indicated extensive bacterial and enzyme activity during aging. However, concentrations of yeast-derived flavor compounds were similar to those of modern beers, except that 3-methylbutyl acetate was unusually low in both beers and 2-phenylethanol and possibly 2-phenylethyl acetate were unusually high in one beer. Concentrations of phenolic compounds were similar to those in modern lagers and ales.

Yeast (Chichester, England), 2015

The objectives of this study were to assess the differences in fermentative behaviour of two diff... more The objectives of this study were to assess the differences in fermentative behaviour of two different strains of Saccharomyces cerevisiae (EC1118 and RC212) and to determine the differences in composition and sensory properties of raspberry wines fermented with immobilized and suspended yeast cells of both strains at 15 °C. Analyses of aroma compounds, glycerol, acetic acid and ethanol, as well as the kinetics of fermentation and a sensory evaluation of the wines, were performed. All fermentations with immobilized yeast cells had a shorter lag phase and faster utilization of sugars and ethanol production than those fermented with suspended cells. Slower fermentation kinetics were observed in all the samples that were fermented with strain RC212 (suspended and immobilized) than in samples fermented with strain EC1118. Significantly higher amounts of acetic acid were detected in all samples fermented with strain RC212 than in those fermented with strain EC1118 (0.282 and 0.602 g/l, r...

Yeast (Chichester, England), 2015

Immobilized cell technology has shown a significant promotional effect on the fermentation of alc... more Immobilized cell technology has shown a significant promotional effect on the fermentation of alcoholic beverages such as beer, wine and cider. However, genetic, morphological and physiological alterations occurring in immobilized yeast cells impact on aroma formation during fermentation processes. The focus of this review is exploitation of existing knowledge on the biochemistry and the biological role of flavour production in yeast for the biotechnological production of aroma compounds of industrial importance, by means of immobilized yeast. Various types of carrier materials and immobilization methods proposed for application in beer, wine, fruit wine, cider and mead production are presented. Engineering aspects with special emphasis on immobilized cell bioreactor design, operation and scale-up potential are also discussed. Ultimately, examples of products with improved quality properties within the alcoholic beverages are addressed, together with identification and description o...

Yeast (Chichester, England), 2015

A screen of 14 S. pastorianus lager-brewing strains showed as much as a nine-fold difference in w... more A screen of 14 S. pastorianus lager-brewing strains showed as much as a nine-fold difference in wort total diacetyl concentration at equivalent stages of fermentation of 15°Plato brewer's wort. Two strains (A153 and W34), with relatively low and high diacetyl production, respectively, but which did not otherwise differ in fermentation performance, growth or flavour production, were selected for further investigation. Transcriptional analysis of key genes involved in valine biosynthesis showed differences between the two strains that were consistent with the differences in wort diacetyl concentration. In particular, the ILV6 gene, encoding a regulatory subunit of acetohydroxy acid synthase, showed early transcription (only 6 h after inoculation) and up to five-fold greater expression in W34 compared to A153. This earlier transcription was observed for both orthologues of ILV6 in the S. pastorianus hybrid (S. cerevisiae × S. eubayanus), although the S. cerevisiae form of ILV6 in W...

Yeast (Chichester, England), 2015

Flavours are biologically active molecules of large commercial interest in the food, cosmetics, d... more Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so-called 'bioflavours', which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini-review, we give an overview of bioflavour production in yeasts from the process-engineering perspective. Two specific examples, production of 2-phenylethanol and vanillin, are used to illustrate the process challenges and strategies used.

Journal of Industrial Microbiology & Biotechnology, 2015

Journal of the Institute of Brewing, 2011

Journal of the Institute of Brewing, 2013

ABSTRACT A pilot-scale fermentation was performed using SSU1-overexpressing bottom-fermenting yea... more ABSTRACT A pilot-scale fermentation was performed using SSU1-overexpressing bottom-fermenting yeast strains constructed by ‘self-cloning’. In these strains, the gene SSU1, encoding a plasma membrane protein that excretes sulphite, was highly expressed. The rate of fermentation of the two SSU1-overexpressing strains tested showed some reduction during the mid-fermentation phase as compared with the parental strain. These differences, however, did not affect overall fermentation and the final apparent extracts had decreased to a level normally obtained during brewing. The concentration of hydrogen sulphide in the wort remained low during fermentation in the case of the two self-cloning strains compared with the parent. The concentration of 2-mercapto-3-methyl-1-butanol, a sulphur compound that causes an ‘onion-like’ off-flavour, was also reduced in the case of the self-cloning strains, a result confirmed by sensory evaluation of the beer immediately after bottling. Furthermore, with these strains the anti-oxidation potential of bottled beer, as measured by electron spin resonance, was improved and the concentration of trans-2-nonenal in bottled beer after 7 days of accelerated aging at 37°C was decreased. These observations, together with the lower stale flavour score determined by sensory evaluation of bottled beer after a month of aging at 25°C, indicated that the flavour stability of the beer had been successfully improved. Copyright © 2013 The Institute of Brewing & Distilling

Journal of Clinical Pathology, 1991

A combination of biological and non-biological factors has led to the interspecific hybrid yeast ... more A combination of biological and non-biological factors has led to the interspecific hybrid yeast species Saccharomyces pastorianus becoming one of the world's most important industrial organisms. This yeast is used in the production of lager-style beers, the fermentation of which requires very low temperatures compared to other industrial fermentation processes. This group of organisms has benefited from both the whole-genome duplication in its ancestral lineage and the subsequent hybridization event between S. cerevisiae and S. eubayanus, resulting in strong fermentative ability. The hybrid has key traits, such as cold tolerance and good maltose- and maltotriose-utilizing ability, inherited either from the parental species or originating from genetic interactions between the parent genomes. Instability in the nascent allopolyploid hybrid genome may have contributed to rapid evolution of the yeast to tolerate conditions prevalent in the brewing environment. The recent discovery of S. eubayanus has provided new insights into the evolutionary history of S. pastorianus and may offer new opportunities for generating novel industrially-beneficial lager yeast strains. Copyright © 2014 John Wiley & Sons, Ltd.

Yeast (Chichester, England), 2015

Flavours are biologically active molecules of large commercial interest in the food, cosmetics, d... more Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so-called 'bioflavours', which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini-review, we give an overview of bioflavour production in yeasts from the process-engineering perspective. Two specific examples, production of 2-phenylethanol and vanillin, are used to illustrate the process challenges and strategies used.

73rd Annual Meeting of the American Society of Brewing Chemists. Rhode Island, USA, 15-18 June 2010

European Yeast Flavour Workshop. COST Action FA0907 Bioflavour. INSA Toulouse, France. 28-29 Oct.... more European Yeast Flavour Workshop. COST Action FA0907 Bioflavour. INSA Toulouse, France. 28-29 Oct. 2010

International Symposium for Young Scientist and Technologists in Malting, Brewing and Distilling.... more International Symposium for Young Scientist and Technologists in Malting, Brewing and Distilling. Freising-Weihenstephan, Germany, 19-21 May 2010

Journal of the American Society of Brewing Chemists

Diacetyl is normally considered to be an off-flavor in lager beer, and its removal prolongs the o... more Diacetyl is normally considered to be an off-flavor in lager beer, and its removal prolongs the overall brewing process. Here, the effects of fermentation temperature (9, 12, and 15°C), initial wort pH (4.8, 5.1, and 5.3), and wort free amino nitrogen (FAN) content (222, 252, 287, and 366 ppm) on diacetyl formation and removal in lager beer fermentations were studied in order to develop an enhanced model for predicting fermentation progress (alcohol content, biomass, and pH) and diacetyl concentration. The relationships between model coefficients, temperature, pH, and FAN were calculated, and models predicted fermentation and diacetyl profiles with a good fit (overall relative mean square error less than 10.1%). The model was validated, and also applied to a larger-scale fermentation involving a different wort and yeast strain by adjusting model coefficients. The model can be used for predicting diacetyl concentrations and for brewing process parameter optimization in industrial fer...

Journal- Institute of Brewing

Sahti, a strong, unhopped farmhouse beer flavoured with juniper is still actively brewed in rural... more Sahti, a strong, unhopped farmhouse beer flavoured with juniper is still actively brewed in rural areas in Finland. Presented here is the first comprehensive analysis of the physical and chemical properties of this unique beer style. Twelve sahti samples from the southwest of Finland were analysed and while properties varied, the beers generally had high levels of alcohol (mean = 7.9% ABV) and high residual extract (mean =

Journal of agricultural and food chemistry, Jan 11, 2015

Two bottles of beer from an about 170-year-old shipwreck (M1 Fö 403.3) near the Åland Islands in ... more Two bottles of beer from an about 170-year-old shipwreck (M1 Fö 403.3) near the Åland Islands in the Baltic Sea were analyzed. Hop components and their degradation compounds showed that the bottles contained two different beers, one more strongly hopped than the other. The hops used contained higher levels of β-acids than modern varieties and were added before the worts were boiled, converting α-acids to iso-α-acids and β-acids to hulupones. High levels of organic acids, carbonyl compounds, and glucose indicated extensive bacterial and enzyme activity during aging. However, concentrations of yeast-derived flavor compounds were similar to those of modern beers, except that 3-methylbutyl acetate was unusually low in both beers and 2-phenylethanol and possibly 2-phenylethyl acetate were unusually high in one beer. Concentrations of phenolic compounds were similar to those in modern lagers and ales.

Yeast (Chichester, England), 2015

The objectives of this study were to assess the differences in fermentative behaviour of two diff... more The objectives of this study were to assess the differences in fermentative behaviour of two different strains of Saccharomyces cerevisiae (EC1118 and RC212) and to determine the differences in composition and sensory properties of raspberry wines fermented with immobilized and suspended yeast cells of both strains at 15 °C. Analyses of aroma compounds, glycerol, acetic acid and ethanol, as well as the kinetics of fermentation and a sensory evaluation of the wines, were performed. All fermentations with immobilized yeast cells had a shorter lag phase and faster utilization of sugars and ethanol production than those fermented with suspended cells. Slower fermentation kinetics were observed in all the samples that were fermented with strain RC212 (suspended and immobilized) than in samples fermented with strain EC1118. Significantly higher amounts of acetic acid were detected in all samples fermented with strain RC212 than in those fermented with strain EC1118 (0.282 and 0.602 g/l, r...

Yeast (Chichester, England), 2015

Immobilized cell technology has shown a significant promotional effect on the fermentation of alc... more Immobilized cell technology has shown a significant promotional effect on the fermentation of alcoholic beverages such as beer, wine and cider. However, genetic, morphological and physiological alterations occurring in immobilized yeast cells impact on aroma formation during fermentation processes. The focus of this review is exploitation of existing knowledge on the biochemistry and the biological role of flavour production in yeast for the biotechnological production of aroma compounds of industrial importance, by means of immobilized yeast. Various types of carrier materials and immobilization methods proposed for application in beer, wine, fruit wine, cider and mead production are presented. Engineering aspects with special emphasis on immobilized cell bioreactor design, operation and scale-up potential are also discussed. Ultimately, examples of products with improved quality properties within the alcoholic beverages are addressed, together with identification and description o...

Yeast (Chichester, England), 2015

A screen of 14 S. pastorianus lager-brewing strains showed as much as a nine-fold difference in w... more A screen of 14 S. pastorianus lager-brewing strains showed as much as a nine-fold difference in wort total diacetyl concentration at equivalent stages of fermentation of 15°Plato brewer's wort. Two strains (A153 and W34), with relatively low and high diacetyl production, respectively, but which did not otherwise differ in fermentation performance, growth or flavour production, were selected for further investigation. Transcriptional analysis of key genes involved in valine biosynthesis showed differences between the two strains that were consistent with the differences in wort diacetyl concentration. In particular, the ILV6 gene, encoding a regulatory subunit of acetohydroxy acid synthase, showed early transcription (only 6 h after inoculation) and up to five-fold greater expression in W34 compared to A153. This earlier transcription was observed for both orthologues of ILV6 in the S. pastorianus hybrid (S. cerevisiae × S. eubayanus), although the S. cerevisiae form of ILV6 in W...

Yeast (Chichester, England), 2015

Flavours are biologically active molecules of large commercial interest in the food, cosmetics, d... more Flavours are biologically active molecules of large commercial interest in the food, cosmetics, detergent and pharmaceutical industries. The production of flavours can take place by either extraction from plant materials, chemical synthesis, biological conversion of precursor molecules or de novo biosynthesis. The latter alternatives are gaining importance through the rapidly growing fields of systems biology and metabolic engineering, giving efficient production hosts for the so-called 'bioflavours', which are natural flavour and/or fragrance compounds obtained with cell factories or enzymatic systems. Yeasts are potential production hosts for bioflavours. In this mini-review, we give an overview of bioflavour production in yeasts from the process-engineering perspective. Two specific examples, production of 2-phenylethanol and vanillin, are used to illustrate the process challenges and strategies used.

Journal of Industrial Microbiology & Biotechnology, 2015