The growth and survival of food-borne pathogens in sweet and fermenting brewers' wort
- Authors: Menz, Garry , Vriesekoop, Frank , Zarei, Mehdi , Zhu, Bofei , Aldred, Peter
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Food Microbiology Vol. 140, no. 1 (2010), p. 19-25
- Full Text: false
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- Description: The aim of this study was to investigate the factors affecting the survival and growth of four food-borne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus) in sweet and fermenting brewery wort. The Gram-negative pathogens (E. coli and Salm. Typhimurium) were capable of growth during the initial stages of fermentation in hopped wort, although they were quickly inactivated when added during the later stages of fermentation. When the wort was left unpitched, the two Gram-negative pathogens grew unabated. Pathogen growth and survival was enhanced as the pH was increased, and as both the ethanol and original gravity were decreased. Although having no effect on the Gram-negative pathogens, low levels of hop iso-
- Description: 2003008146
The presence and role of Thiamine and Riboflavin in the malting and brewing industries
- Authors: Hucker, Barry
- Date: 2013
- Type: Text , Thesis , PhD
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- Description: Thiamine and riboflavin vitamers are present in a wide range of foods including beer. They play critical roles in a variety of enzymatic complexes and can promote and maintain metabolism. Currently, the presence and role of these vitamers in the malting and brewing industry has not been widely explored. This research has investigated the effects of various malting and brewing processes on the final thiamine and riboflavin vitamer content of finished beer. In order to achieve this, a highly accurate and reproducible HPLC (spike recovery > 95 %; RSD < 5.0 %) method was developed that allowed the separation of thiamine diphosphate (TDP), thiamine monophosphate (TMP), thiamine, riboflavin 5-phosphate (FMN) and riboflavin in various sample matrices. This method was utilised to determine the vitamer content of various cereals and malts and it was found that malting vastly alters the thiamine content of malted barley, while it has minimal effect on riboflavin content. When malted barley is roasted, all vitamers are rapidly degraded. The mashing process releases the various vitamers into a solution and this release is dependent on temperature and enzymatic activity, while wort boiling significantly reduces the vitamer content of the wort. During fermentation, the thiamine content of wort is quickly utilised within the first six hours of standard fermentations and the uptake of this vitamin is not affected by increases in wort gravity. Meanwhile riboflavin is only poorly utilised during these fermentations. Post-fermentative additives, such as the addition of tannic acid and potassium metabisulphite, negatively affect the vitamin content of the final product while phosphorylated forms of these vitamins are greatly affected by the addition of many post-fermentative processing aids/additives. The presence of both thiamine and riboflavin can enhance the spoilage of beer by known brewery spoilage organisms, and the incorrect storage of bottle-conditioned beer can negatively affect the vitamin and organoleptic properties of the final product. These various steps involved in the production of beer greatly affect the final vitamin content, and this knowledge helps to explain the large variation in the thiamine and riboflavin vitamer content of a survey of 204 commercially available beers. This survey concluded that despite the large variations within particular styles of beer, lagers contain the least amount of thiamine compared to ales, stout/porters and wheat beers. However the average riboflavin content of the tested beers was statistically similar (p = 0.608) across all of the styles. This is due to the limited utilisation of this vitamin during fermentations.
- Description: Doctor of Philosophy
The quantitative analysis of thiamin and riboflavin and their respective vitamers in fermented alcoholic beverages
- Authors: Hucker, Barry , Wakeling, Lara , Vriesekoop, Frank
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Agricultural and Food Chemistry Vol. 59, no. 23 (2011), p. 12278-12285
- Full Text: false
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- Description: This research aimed to develop a simple and effective method for analyzing thiamin (B 1), riboflavin (B 2) and their respective vitamers by high performance liquid chromatography (HPLC) in fermented alcoholic beverages. The method developed here employs a phosphate buffer/methanol gradient elution on a single reverse phase column, coupled with independent fluorescent detection regimes. It also employs a precolumn derivatization to convert thiamin to thiochrome via an alkaline potassium ferricyanide solution. The method described here allowed a spike recovery of better than 97%, with a typical linear detection range (R 2 ≥ 0.9997) between ≥5 and ≥500
Growth and survival of foodborne pathogens in beer
- Authors: Menz, Garry , Aldred, Peter , Vriesekoop, Frank
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Food Protection Vol. 74, no. 10 (2011), p. 1670-1675
- Full Text: false
- Reviewed:
- Description: This work aimed to assess the growth and survival of four foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus) in beer. The effects of ethanol, pH, and storage temperature were investigated for the gram-negative pathogens (E. coli O157:H7 and Salmonella Typhimurium), whereas the presence of hops ensured that the gram-positive pathogens (L. monocytogenes and S. aureus) were rapidly inactivated in alcohol-free beer. The pathogens E. coli O157:H7 and Salmonella Typhimurium could not grow in the mid-strength or full-strength beers, although they could survive for more than 30 days in the mid-strength beer when held at 4°C. These pathogens grew rapidly in the alcoholfree beer; however, growth was prevented when the pH of the alcohol-free beer was lowered from the "as received" value of 4.3 to 4.0. Pathogen survival in all beers was prolonged at lowered storage temperatures. Copyright © International Association for Food Protection.
The influence of thiamine and riboflavin on various spoilage microorganisms commonly found in beer
- Authors: Hucker, Barry , Christophersen, Melinda , Vriesekoop, Frank
- Date: 2017
- Type: Text , Journal article
- Relation: Journal of the Institute of Brewing Vol. 123, no. 1 (2017), p. 24-30
- Full Text: false
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- Description: Beer is generally considered a stable product owing to its intrinsic ‘unfavourable’ conditions (hops, alcohol, low oxygen, etc.) that inhibit the growth of pathogenic microorganisms. However spoilage microorganism such as Lactobacillus brevis, Pediococcus damnosus, Acetobacter aceti, Zymomonas mobilis and various wild yeasts (e.g. Brettanomcyes spp.) can have significant detrimental effects on the organoleptic properties of the final product. The presence of essential vitamins, such as thiamine and riboflavin, can help to enhance the growth of these microorganisms, accelerating the rate of spoilage. The presence of thiamine had a noticeable effect on the lactic acid productivity of L. brevis and P. damnosus, acetaldehyde productivity of Z. mobilis and acetic acid production of Brettanomyces spp., while riboflavin enhanced 2,3-pentanedione production by P. damnosus and Brettanomyces spp. Copyright © 2017 The Institute of Brewing & Distilling. Copyright © 2017 The Institute of Brewing & Distilling
Glass shape influences the flavour of beer
- Authors: Mirabito, Adrian , Oliphant, Markus , Van Doorn, George , Watson, Shaun , Spence, Charles
- Date: 2017
- Type: Text , Journal article
- Relation: Food Quality and Preference Vol. 62, no. (2017), p. 257-261
- Full Text: false
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- Description: It is often said that our perception of wine varies as a function of the receptacle in which it is presented. Indeed, glassware has been the subject of extensive study in this category. By contrast, the impact of glassware on the perception of beer has been largely ignored in the field of sensory science research. The current study was specifically designed to investigate the influence of the shape (specifically side curvature) of the glass on people’s perception of beer. Fifty-three Australian participants rated (on 10-point Likert scales) a beer presented in one of two glasses. The beer was perceived as being fruitier and more intense when served in a curved-sided glass. Given previous research showing that people match fruitiness with curvature (rather than straightness/angularity), these results fit within the existing literature on crossmodal correspondences between shape and taste properties.
Brewers and vintners beware!: Mitigation of the carbon dioxide hazard in the fermentation industries using hierarchy of control methodology
- Authors: Young, Stephen , Naiker, Mani , Aldred, Peter
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Health, Safety and Environment Vol. 31, no. 3 (2015), p.
- Full Text: false
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- Description: This paper suggests that elevated levels of CO2 are a widely underestimated occupational hazard for those working in the fermentation industries. The generation of CO2 as a natural by-product of fermentation, and the input of additional CO2, are examined and the potential CO2 hazard highlighted. The need for the rapidly growing fermentation industries to understand and mitigate this hazard is emphasised. A robust application of hierarchy of controls methodology is employed to effect a bestpractice mitigation of the CO2 hazard. The paper concludes with a strong recommendation for the use of automated monitoring linked to lock out mechanisms as the most effective means of assuring worker safety with respect to elevated levels of CO2 in the workplace. © CCH.
Happy hour? A preliminary study of the effect of induced joviality and sadness on beer perception
- Authors: Desira, Beth , Watson, Shaun , Van Doorn, George , Timora, Justin , Spence, Charles
- Date: 2020
- Type: Text , Journal article
- Relation: Beverages Vol. 6, no. 2 (2020), p. 1-14
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- Description: Our emotions influence our perception. In order to determine whether emotion influences the perception of beer, 32 participants watched either a scene from the movie Wall-E to induce joviality, or a short clip from the Shawshank Redemption to induce sadness. The participants were then required to sample up to 250 mL of Yenda Pale Ale beer and rate it on a variety of taste and flavor characteristics (e.g., bitterness), before completing the Positive and Negative Affect Schedule-X (PANAS-X). The data were analyzed using Bayesian t-tests and Null Hypothesis Significance Tests (NHSTs). After applying conservative corrections for multiple comparisons, NHSTs failed to reach statistical significance. However, the effect sizes suggested that inducing joviality, relative to inducing sadness, resulted in the beer being rated as (a) tasting more pleasant, (b) tasting sweeter, and (c) being of higher quality. Following the induction of joviality, participants were also willing to pay more for the beer. The Bayesian analyses indicated that induced emotion can influence flavor perception for complex taste stimuli. The effect sizes and Bayesian analyses are interpreted in terms of Feelings-as-Information theory. These preliminary findings can tentatively be applied to real-world environments such as venues that serve and/or market alcohol. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Description: Funding: This research was funded by the Arts and Humanities Research Council (AHRC), grant number AH/L007053/1 awarded to C.S.
The visual appearance of beer : A review concerning visually-determined expectations and their consequences for perception
- Authors: Van Doorn, George , Timora, Justin , Watson, Shaun , Moore, Chris , Spence, Charles
- Date: 2019
- Type: Text , Journal article , Review
- Relation: Food Research International Vol. 126, no. (2019), p.
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- Description: This review critically evaluates the literature concerning the impact of visual appearance cues (including colour, foam, and cloudiness) on people's perception in the beer category. The authors assess both the sensory expectations that are elicited by the visual appearance of beer, and the extent to which those expectations carry-over to influence the actual tasting experience. Beer is a particularly intriguing category to study since the differing production rules in different countries mean that there is not always the same scope to modify the colour in order to meet perceived consumer demands. What is more, there is currently disagreement in the literature concerning the impact of beer colour and foam on people's expectations of beer prior to tasting, and their multisensory flavour perception on tasting. Given how much beer is consumed annually, it is surprising that more research has not been published that assesses the undoubtedly important role of visual appearance in this beverage category. Part of the reason for this may simply be that it is difficult to create consistent experimental stimuli given the rapid transition of the head of the beer post-serving. © 2019 Elsevier Ltd
The effect of water-soluble vitamins on spoilage organisms in beer
- Authors: Hucker, Barry , Wakeling, Lara , Vriesekoop, Frank
- Date: 2010
- Type: Text , Conference paper
- Relation: 31st Asia Pacific Convention 2010
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- Description: The vitamin content of beer and brewing related products might not only be of interest from a human health perspective, but determining their presence and relative quantities might also help to understand the role they play in product stability. Water-soluble vitamins are important in the brewing industry, as they are essential nutrients for yeasts and potential spoilage organisms. The presence of particular vitamins in beer has been linked to deterioration (light strike) and it is possible that many vitamins may be linked to increased bacterial spoilage potential in beer. There is strong evidence to support that lactic acid bacteria require a variety of vitamins in order to grow effectively and can aid in the increased spoilage of beer and beer related products. This study investigates the effect of a variety of water-soluble vitamins on the growth of commonly found spoilage organisms, Lactobacillus brevis and Pediococcus damnosus.
A preliminary investigation of the effect of ethical labeling and moral self-image on the expected and perceived flavor and aroma of beer
- Authors: Doorn, George , Ferguson, Rose , Watson, Shaun , Timora, Justin , Berends, Dylan , Moore, Chris
- Date: 2021
- Type: Text , Journal article
- Relation: Beverages Vol. 7, no. 2 (2021), p.
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- Description: Ethical labelling has been shown to influence taste/flavour perception. Across two experiments, the present study examined how ethical labelling and moral self-image influenced both the expected (Experiment One) and perceived (Experiment Two) taste/flavour characteristics of beer. In Experiment One, 170 participants read either a ‘moral’ or ‘control’ label describing a brewery, after which they were presented with an image of a beer. Participants then completed a Beer Taste Perception Questionnaire and the Moral Self-Image Scale. In Experiment Two, 59 participants were exposed to either the moral or control label before tasting a beer and completing the same questionnaires from Experiment One. The results of Experiment One indicated that label type moderated the relationship between moral self-image and the intensity ratings of the beer. Specifically, in the presence of a control label, the expected intensity of the beer’s flavour increased as moral self-image increased. Experiment Two found no evidence that the moral label influenced the perceived taste of the beer. However, the results showed that as moral self-image became more positive the perceived refreshingness of the beer increased. This study provides novel evidence of the potential relationship between an individual’s moral self-image and the expected and perceived taste/flavour characteristics of beer. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.