The Preservative Sorbic Acid Targets Respiration, Explaining the Resistance of Fermentative Spoilage Yeast Species

ABSTRACT A small number (10 to 20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like sorbic acid, and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only, and most of these are sorbic acid sensitive and so prevented from causing spoilage. This led us to hypothesize that sorbic acid may specifically inhibit respiration. Tests with respirofermentative yeasts showed that sorbic acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) than during fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables sorbic acid-resistant growth. Sorbic acid inhibited the respiration process more strongly than fermentation. We present a data set supporting a correlation between the level of fermentation and sorbic acid resistance across 191 yeast species. Other weak acids, C2 to C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic acidification. Supporting this, we present evidence that sorbic acid causes production of reactive oxygen species, the formation of petite (mitochondrion-defective) cells, and Fe-S cluster defects. This work rationalizes why yeasts that can grow in sorbic acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favor respiration over fermentation in many spoilage yeasts. IMPORTANCE Spoilage by yeasts and molds is a major contributor to food and drink waste, which undermines food security. Weak acid preservatives like sorbic acid help to stop spoilage, but some yeasts, commonly associated with spoilage, are resistant to sorbic acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here, we show that sorbic acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of sorbic acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as the sugar content of products like soft drinks is being lowered, which may favor respiration over fermentation in key spoilage yeasts.

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The preservative sorbic acid targets respiration, explaining the resistance of fermentative spoilage-yeast species

10.1101/2020.04.09.034074 ◽

2020 ◽

Cited By ~ 2

Author(s):

M. Stratford ◽

C. Vallières ◽

I.A. Geoghegan ◽

D.B. Archer ◽

S.V. Avery

Keyword(s):

Sorbic Acid ◽

Yeast Species ◽

Sugar Content ◽

Acid Resistance ◽

Rhodotorula Glutinis ◽

Weak Acid ◽

Soft Drinks ◽

Effective Control ◽

Spoilage Yeast ◽

Spoilage Yeasts

ABSTRACTA small number (10-20) of yeast species cause major spoilage in foods. Spoilage yeasts of soft drinks are resistant to preservatives like sorbic acid and they are highly fermentative, generating large amounts of carbon dioxide gas. Conversely, many yeast species derive energy from respiration only and most of these are sorbic acid-sensitive, so prevented from causing spoilage. This led us to hypothesize that sorbic acid may specifically inhibit respiration. Tests with respiro-fermentative yeasts showed that sorbic acid was more inhibitory to both Saccharomyces cerevisiae and Zygosaccharomyces bailii during respiration (of glycerol) compared with fermentation (of glucose). The respiration-only species Rhodotorula glutinis was equally sensitive when growing on either carbon source, suggesting that ability to ferment glucose specifically enables sorbic acid-resistant growth. Sorbic acid inhibited the respiration process more strongly than fermentation. We present a dataset supporting a correlation between the level of fermentation and sorbic acid resistance across 191 yeast species. Other weak acids, C2 – C8, inhibited respiration in accordance with their partition coefficients, suggesting that effects on mitochondrial respiration were related to membrane localization rather than cytosolic acidification. Supporting this, we present evidence that sorbic acid causes production of reactive oxygen species, the formation of petite (mitochondria-defective) cells, and Fe-S cluster defects. This work rationalises why yeasts that can grow in sorbic acid-preserved foods tend to be fermentative in nature. This may inform more-targeted approaches for tackling these spoilage organisms, particularly as the industry migrates to lower-sugar drinks, which could favour respiration over fermentation in many spoilage yeasts.IMPORTANCESpoilage by yeasts and moulds is a major contributor to food and drink waste, which undermines food security. Weak acid preservatives like sorbic acid help to stop spoilage but some yeasts, commonly associated with spoilage, are resistant to sorbic acid. Different yeasts generate energy for growth by the processes of respiration and/or fermentation. Here we show that sorbic acid targets the process of respiration, so fermenting yeasts are more resistant. Fermentative yeasts are also those usually found in spoilage incidents. This insight helps to explain the spoilage of sorbic acid-preserved foods by yeasts and can inform new strategies for effective control. This is timely as sugar content of products like soft drinks is being lowered, which may favour respiration over fermentation in key spoilage yeasts.

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Vinification without Saccharomyces: Interacting Osmotolerant and “Spoilage” Yeast Communities in Fermenting and Ageing Botrytised High-Sugar Wines (Tokaj Essence)

Microorganisms ◽

10.3390/microorganisms9010019 ◽

2020 ◽

Vol 9 (1) ◽

pp. 19

Author(s):

Hajnalka Csoma ◽

Zoltán Kállai ◽

Zsuzsa Antunovics ◽

Kinga Czentye ◽

Matthias Sipiczki

Keyword(s):

Fragment Length Polymorphism ◽

Sugar Content ◽

Grape Juice ◽

Minor Components ◽

Additional Species ◽

Spoilage Yeast ◽

Genetic Segregation ◽

Spoilage Yeasts ◽

Molecular Karyotype ◽

Restriction Fragment Length

The conversion of grape juice to wine starts with complex yeast communities consisting of strains that have colonised the harvested grape and/or reside in the winery environment. As the conditions in the fermenting juice gradually become inhibitory for most species, they are rapidly overgrown by the more adaptable Saccharomyces strains, which then complete the fermentation. However, there are environmental factors that even Saccharomyces cannot cope with. We show that when the sugar content is extremely high, osmotolerant yeasts, usually considered as “spoilage yeasts“, ferment the must. The examination of the yeast biota of 22 botrytised Tokaj Essence wines of sugar concentrations ranging from 365 to 752 g∙L−1 identified the osmotolerant Zygosaccharomyces rouxii, Candida (Starmerella) lactis-condensi and Candida zemplinina (Starmerella bacillaris) as the dominating species. Ten additional species, mostly known as osmotolerant spoilage yeasts or biofilm-producing yeasts, were detected as minor components of the populations. The high phenotypical and molecular (karyotype, mtDNA restriction fragment length polymorphism (RFLP) and microsatellite-primed PCR (MSP-PCR)) diversity of the conspecific strains indicated that diverse clones of the species coexisted in the wines. Genetic segregation of certain clones and interactions (antagonism and crossfeeding) of the species also appeared to shape the fermenting yeast biota.

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Level of food additives, caffeine and total sugars in locally manufactured beverages in Mauritius and their compliance with national and international norms

British Food Journal ◽

10.1108/bfj-03-2019-0189 ◽

2019 ◽

Vol 121 (11) ◽

pp. 2849-2866

Author(s):

Dhamawatee Harnarun Etwaroo ◽

Viswen Armoogum ◽

Dayawatee Goburdhun ◽

Arvind Ruggoo ◽

Pooja Dookheea ◽

...

Keyword(s):

Citric Acid ◽

Sorbic Acid ◽

Food Additives ◽

Soft Drinks ◽

International Norms ◽

Brilliant Blue ◽

Sunset Yellow ◽

Total Sugars ◽

Content Type ◽

Validation Parameters

Purpose The purpose of this paper is to determine the level of food additives, caffeine and total sugars in locally manufactured beverages in Mauritius and ascertain their compliance with national and international norms. Design/methodology/approach In total, 48 beverages: 21 soft drinks, 14 ice teas, 5 fruit drinks, 5 nonalcoholic sparkling drinks and 3 tonic waters were analysed for the level of sweeteners (aspartame, acesulfame K and saccharin), preservatives (benzoic and sorbic acid), colours (tartrazine, sunset yellow, quinoline yellow, allura red, amaranth, ponceau 4R, carmoisine, erythrosine, brilliant blue, green S and patent blue), citric acid, caffeine and total sugars. High-performance liquid chromatography methods used to quantify the levels of total sugars, caffeine and additives were validated against parameters such as linearity, recovery, accuracy, precision and limit of quantification. Findings Out of 48 beverages, 13 contained at least one sweetener. The most frequently used sweeteners were acesulfame K and aspartame. Benzoic acid was present in 27 samples (42.32–168.03 mg/L). Sorbic acid was present in 14 beverages (13.01–180.38 mg/L). Citric acid (0.7–4 g/L) was present in all the 48 beverages, while caffeine was present in 20 samples in the range of 14.01–129.42 mg/L. Nine samples contained at least one artificial colour and the most frequently used colours were tartrazine, sunset yellow, brilliant blue and carmoisine. The average level of total sugars present in the beverages was 10 g/100 ml. The validation parameters obtained showed evidence for method suitability. Research limitations/implications Beverages sold by individuals on the street, small restaurants and markets were not analysed. Originality/value This study provides an overview of the chemical composition of soft drinks and their compliance with Food Regulations. It also paves the way to investigate weaknesses, knowledge, attitudes and practices of local manufacturers, which leads to non-adherence to Regulations regarding food additives.

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Decarboxylation of Sorbic Acid by Spoilage Yeasts Is Associated with the PAD1 Gene

Applied and Environmental Microbiology ◽

10.1128/aem.01246-07 ◽

2007 ◽

Vol 73 (20) ◽

pp. 6534-6542 ◽

Cited By ~ 53

Author(s):

Malcolm Stratford ◽

Andrew Plumridge ◽

David B. Archer

Keyword(s):

Carboxylic Acids ◽

Cinnamic Acid ◽

Sorbic Acid ◽

Debaryomyces Hansenii ◽

Pichia Anomala ◽

Gas Chromatography Mass Spectrometry ◽

Cinnamic Acids ◽

Mechanism Of Resistance ◽

Spoilage Yeast ◽

Spoilage Yeasts

ABSTRACT The spoilage yeast Saccharomyces cerevisiae degraded the food preservative sorbic acid (2,4-hexadienoic acid) to a volatile hydrocarbon, identified by gas chromatography mass spectrometry as 1,3-pentadiene. The gene responsible was identified as PAD1, previously associated with the decarboxylation of the aromatic carboxylic acids cinnamic acid, ferulic acid, and coumaric acid to styrene, 4-vinylguaiacol, and 4-vinylphenol, respectively. The loss of PAD1 resulted in the simultaneous loss of decarboxylation activity against both sorbic and cinnamic acids. Pad1p is therefore an unusual decarboxylase capable of accepting both aromatic and aliphatic carboxylic acids as substrates. All members of the Saccharomyces genus (sensu stricto) were found to decarboxylate both sorbic and cinnamic acids. PAD1 homologues and decarboxylation activity were found also in Candida albicans, Candida dubliniensis, Debaryomyces hansenii, and Pichia anomala. The decarboxylation of sorbic acid was assessed as a possible mechanism of resistance in spoilage yeasts. The decarboxylation of either sorbic or cinnamic acid was not detected for Zygosaccharomyces, Kazachstania (Saccharomyces sensu lato), Zygotorulaspora, or Torulaspora, the genera containing the most notorious spoilage yeasts. Scatter plots showed no correlation between the extent of sorbic acid decarboxylation and resistance to sorbic acid in spoilage yeasts. Inhibitory concentrations of sorbic acid were almost identical for S. cerevisiae wild-type and Δpad1 strains. We concluded that Pad1p-mediated sorbic acid decarboxylation did not constitute a significant mechanism of resistance to weak-acid preservatives by spoilage yeasts, even if the decarboxylation contributed to spoilage through the generation of unpleasant odors.

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Financial distress determinants among SMEs: empirical evidence from Sweden

Journal of Economic Studies ◽

10.1108/jes-01-2019-0030 ◽

2020 ◽

Vol 47 (3) ◽

pp. 547-560 ◽

Cited By ~ 1

Author(s):

Darush Yazdanfar ◽

Peter Öhman

Keyword(s):

Financial Crisis ◽

Financial Distress ◽

Large Scale ◽

Global Financial Crisis ◽

Binary Logistic Regression ◽

Data Availability ◽

Cross Sectional ◽

Data Set ◽

Content Type ◽

The Global Financial Crisis

PurposeThe purpose of this study is to empirically investigate determinants of financial distress among small and medium-sized enterprises (SMEs) during the global financial crisis and post-crisis periods.Design/methodology/approachSeveral statistical methods, including multiple binary logistic regression, were used to analyse a longitudinal cross-sectional panel data set of 3,865 Swedish SMEs operating in five industries over the 2008–2015 period.FindingsThe results suggest that financial distress is influenced by macroeconomic conditions (i.e. the global financial crisis) and, in particular, by various firm-specific characteristics (i.e. performance, financial leverage and financial distress in previous year). However, firm size and industry affiliation have no significant relationship with financial distress.Research limitationsDue to data availability, this study is limited to a sample of Swedish SMEs in five industries covering eight years. Further research could examine the generalizability of these findings by investigating other firms operating in other industries and other countries.Originality/valueThis study is the first to examine determinants of financial distress among SMEs operating in Sweden using data from a large-scale longitudinal cross-sectional database.

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Light touch, heavy hand: principals and data-use PLCs

Journal of Educational Administration ◽

10.1108/jea-09-2016-0101 ◽

2017 ◽

Vol 55 (4) ◽

pp. 376-389 ◽

Cited By ~ 10

Author(s):

Alice Huguet ◽

Caitlin C. Farrell ◽

Julie A. Marsh

Keyword(s):

Professional Learning ◽

Low Income ◽

Equal Opportunity ◽

Data Use ◽

Opportunity To Learn ◽

School Level ◽

Comparative Case Study ◽

Data Set ◽

Content Type ◽

Principal's Role

Purpose The use of data for instructional improvement is prevalent in today’s educational landscape, yet policies calling for data use may result in significant variation at the school level. The purpose of this paper is to focus on tools and routines as mechanisms of principal influence on data-use professional learning communities (PLCs). Design/methodology/approach Data were collected through a comparative case study of two low-income, low-performing schools in one district. The data set included interview and focus group transcripts, observation field notes and documents, and was iteratively coded. Findings The two principals in the study employed tools and routines differently to influence ways that teachers interacted with data in their PLCs. Teachers who were given leeway to co-construct data-use tools found them to be more beneficial to their work. Findings also suggest that teachers’ data use may benefit from more flexibility in their day-to-day PLC routines. Research limitations/implications Closer examination of how tools are designed and time is spent in data-use PLCs may help the authors further understand the influence of the principal’s role. Originality/value Previous research has demonstrated that data use can improve teacher instruction, yet the varied implementation of data-use PLCs in this district illustrates that not all students have an equal opportunity to learn from teachers who meaningfully engage with data.

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Study on the Inhibitory Activity of a Synthetic Defensin Derived from Barley Endosperm against Common Food Spoilage Yeast

Molecules ◽

10.3390/molecules26010165 ◽

2020 ◽

Vol 26 (1) ◽

pp. 165

Author(s):

Laila N. Shwaiki ◽

Aylin W. Sahin ◽

Elke K. Arendt

Keyword(s):

Apple Juice ◽

Digestive Enzyme ◽

Inhibitory Effect ◽

Food Preservation ◽

Food Spoilage ◽

Inhibitory Effects ◽

Barley Endosperm ◽

Spoilage Yeast ◽

Spoilage Yeasts ◽

Spoilage Microorganisms

In the food industry, food spoilage is a real issue that can lead to a significant amount of waste. Although current preservation techniques are being applied to reduce the occurrence of spoilage microorganisms, the problem persists. Food spoilage yeast are part of this dilemma, with common spoilers such as Zygosaccharomyces, Kluyveromyces, Debaryomyces and Saccharomyces frequently encountered. Antimicrobial peptides derived from plants have risen in popularity due to their ability to reduce spoilage. This study examines the potential application of a synthetic defensin peptide derived from barley endosperm. Its inhibitory effect against common spoilage yeasts, its mechanisms of action (membrane permeabilisation and overproduction of reactive oxygen species), and its stability in different conditions were characterised. The safety of the peptide was evaluated through a haemolysis and cytotoxicity assay, and no adverse effects were found. Both assays were performed to understand the effect of the peptide if it were to be consumed. Its ability to be degraded by a digestive enzyme was also examined for its safety. Finally, the peptide was successfully applied to different beverages and maintained the same inhibitory effects in apple juice as was observed in the antiyeast assays, providing further support for its application in food preservation.

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A dynamic simulator for the ergonomics evaluation of powered torque tools for human assembly

Assembly Automation ◽

10.1108/aa-12-2015-126 ◽

2017 ◽

Vol 37 (1) ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Haluk Ay ◽

Anthony Luscher ◽

Carolyn Sommerich

Keyword(s):

Risk Factors ◽

Joint Torque ◽

Human Hand ◽

Model Parameters ◽

Test Rig ◽

Musculoskeletal Discomfort ◽

Data Set ◽

Content Type ◽

Working Posture ◽

Displacement Measurements

Purpose The purpose of this study is to design and develop a testing device to simulate interaction between human hand–arm dynamics, right-angle (RA) computer-controlled power torque tools and joint-tightening task-related variables. Design/methodology/approach The testing rig can simulate a variety of tools, tasks and operator conditions. The device includes custom data-acquisition electronics and graphical user interface-based software. The simulation of the human hand–arm dynamics is based on the rig’s four-bar mechanism-based design and mechanical components that provide adjustable stiffness (via pneumatic cylinder) and mass (via plates) and non-adjustable damping. The stiffness and mass values used are based on an experimentally validated hand–arm model that includes a database of model parameters. This database is with respect to gender and working posture, corresponding to experienced tool operators from a prior study. Findings The rig measures tool handle force and displacement responses simultaneously. Peak force and displacement coefficients of determination (R2) between rig estimations and human testing measurements were 0.98 and 0.85, respectively, for the same set of tools, tasks and operator conditions. The rig also provides predicted tool operator acceptability ratings, using a data set from a prior study of discomfort in experienced operators during torque tool use. Research limitations/implications Deviations from linearity may influence handle force and displacement measurements. Stiction (Coulomb friction) in the overall rig, as well as in the air cylinder piston, is neglected. The rig’s mechanical damping is not adjustable, despite the fact that human hand–arm damping varies with respect to gender and working posture. Deviations from these assumptions may affect the correlation of the handle force and displacement measurements with those of human testing for the same tool, task and operator conditions. Practical implications This test rig will allow the rapid assessment of the ergonomic performance of DC torque tools, saving considerable time in lineside applications and reducing the risk of worker injury. DC torque tools are an extremely effective way of increasing production rate and improving torque accuracy. Being a complex dynamic system, however, the performance of DC torque tools varies in each application. Changes in worker mass, damping and stiffness, as well as joint stiffness and tool program, make each application unique. This test rig models all of these factors and allows quick assessment. Social implications The use of this tool test rig will help to identify and understand risk factors that contribute to musculoskeletal disorders (MSDs) associated with the use of torque tools. Tool operators are subjected to large impulsive handle reaction forces, as joint torque builds up while tightening a fastener. Repeated exposure to such forces is associated with muscle soreness, fatigue and physical stress which are also risk factors for upper extremity injuries (MSDs; e.g. tendinosis, myofascial pain). Eccentric exercise exertions are known to cause damage to muscle tissue in untrained individuals and affect subsequent performance. Originality/value The rig provides a novel means for quantitative, repeatable dynamic evaluation of RA powered torque tools and objective selection of tightening programs. Compared to current static tool assessment methods, dynamic testing provides a more realistic tool assessment relative to the tool operator’s experience. This may lead to improvements in tool or controller design and reduction in associated musculoskeletal discomfort in operators.

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Seven-year trends in the availability, sugar content and serve size of single-serve non-alcoholic beverages in New Zealand: 2013–2019

Public Health Nutrition ◽

10.1017/s1368980020005030 ◽

2020 ◽

pp. 1-13

Author(s):

Teresa Gontijo de Castro ◽

Helen Eyles ◽

Cliona Ni Mhurchu ◽

Leanne Young ◽

Sally Mackay

Keyword(s):

New Zealand ◽

Sugar Content ◽

Food Composition ◽

Soft Drinks ◽

Alcoholic Beverages ◽

Slight Reduction ◽

Cross Sectional ◽

Sweetened Beverages ◽

Sugary Drinks ◽

High Sugar Content

Abstract Objective: To assess trends in relative availability, sugar content and serve size of ready-to-drink non-alcoholic beverages available for sale in supermarkets from 2013 to 2019. Design: Repeat cross-sectional surveys. Data on single-serve beverages to be consumed in one sitting were obtained from an updated brand-specific food composition database. Trends in beverages availability and proportions with serve size ≤ 250 ml were assessed by χ2 tests. Sugar content trends were examined using linear regressions. The proportion of beverages exceeding the sugar threshold of the United Kingdom Soft Drinks Industry Levy (SDIL) was assessed. Setting: New Zealand. Results: From 2013 to 2019, there was (i) an increase in the availability of sugar-free/low-sugar beverages (n 25 (8·4 %) to n 75 (19·1 %); P < 0·001) and craft sugar-sweetened soft drinks (n 11 (3·7 %) to n 36 (9·2 %); P < 0·001), and a decrease in availability of fruit/vegetable juices/drinks (n 94 (31·8 %) to n 75 (19·4 %); P < 0·001); (ii) small decreases in sugar content (mean g/100 ml) of sugar-sweetened soft drinks (3·03; 95 % CI 3·77, 2·29); fruit/vegetable juices/drinks (1·08; 95 % CI 2·14, 0·01) and energy drinks (0·98; 95 % CI 1·63, 0·32) and (iii) slight reduction in the proportion of beverages with serve size ≤ 250 ml (21·6 to 18·9 %; P < 0·001). In 2019, most beverages were sugar-sweetened or had naturally occurring sugars (79·1 %) and serve size > 250 ml (81·1 %) and most sugar-sweetened beverages exceeded the SDIL lower benchmark (72·9 %). Conclusions: Most single-serve beverages available for sale in 2019 were sugary drinks with high sugar content and large serve sizes; therefore, changes made across the years were not meaningful for population’s health.

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Use of Basu-Dhar bivariate geometric distribution in the analysis of the reliability of component series systems

International Journal of Quality & Reliability Management ◽

10.1108/ijqrm-05-2018-0115 ◽

2019 ◽

Vol 36 (4) ◽

pp. 569-586

Author(s):

Ricardo Puziol Oliveira ◽

Jorge Alberto Achcar

Keyword(s):

Bayesian Approach ◽

Geometric Distribution ◽

Bivariate Distribution ◽

Dependence Structure ◽

Series System ◽

Engineering Applications ◽

Data Set ◽

Content Type ◽

Bivariate Geometric Distribution ◽

Series Systems

Purpose The purpose of this paper is to provide a new method to estimate the reliability of series system by using a discrete bivariate distribution. This problem is of great interest in industrial and engineering applications. Design/methodology/approach The authors considered the Basu–Dhar bivariate geometric distribution and a Bayesian approach with application to a simulated data set and an engineering data set. Findings From the obtained results of this study, the authors observe that the discrete Basu–Dhar bivariate probability distribution could be a good alternative in the analysis of series system structures with accurate inference results for the reliability of the system under a Bayesian approach. Originality/value System reliability studies usually assume independent lifetimes for the components (series, parallel or complex system structures) in the estimation of the reliability of the system. This assumption in general is not reasonable in many engineering applications, since it is possible that the presence of some dependence structure between the lifetimes of the components could affect the evaluation of the reliability of the system.

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