Cardinal Temperatures for Growth of Osmotolerant Yeasts in Broths at Different Water Activity Values

1987 ◽  
Vol 50 (6) ◽  
pp. 473-478 ◽  
Author(s):  
MARCO F. G. JERMINI ◽  
WILHELM SCHMIDT-LORENZ
Keyword(s):  
Water Activity ◽  
Debaryomyces Hansenii ◽  
Torulaspora Delbrueckii ◽  
Zygosaccharomyces Rouxii ◽  
High Sugar ◽  
Cardinal Temperatures

All three cardinal temperatures (Tmin, Topt and Tmax) for growth of 6 strains as well as Tmin and Tmax for growth of an additional 23 strains were determined in solutions of 10, 30, 50 and 60% (w/w) glucose at aw (20°C) of 0.990, 0.970, 0.922 and 0.868, respectively. The Topt for growth of Zygosaccharomyces rouxii and Z. bisporus were 24–28.5°C at aw >0.990 and 31–33°C at aw in the range of 0.922–0.868. Z. bailii showed Topt for growth of 29–31°C and 33–35°C at aw >0.990 and aw <0.922, respectively. The Topt for growth of Torulaspora delbrueckii was 27–28.5°C at aw <0.990 and 31–33.5 at aw in the range of 0.922–0.868. Debaryomyces hansenii showed a Topt of 24°C and 27–29.5°C at aw >0.990 and aw <0.922, respectively. The Tmin and Tmax for growth were also shifted toward higher values as the aw decreased; at aw<0.922 none of the tested strains grew at 4°C within 30 d. Several strains could grow at 42°C only in the presence of high sugar concentrations.

Detection, Isolation and Identification of Osmotolerant Yeasts from High-Sugar Products

1987 ◽  
Vol 50 (6) ◽  
pp. 468-472 ◽  
Author(s):  
MARCO F. G. JERMINI ◽  
OTTO GEIGES ◽  
WILHELM SCHMIDT-LORENZ
Keyword(s):  
Yeast Extract ◽  
Enrichment Culture ◽  
Debaryomyces Hansenii ◽  
Yeast Cells ◽  
Isolation And Identification ◽  
Torulaspora Delbrueckii ◽  
Enrichment Medium ◽  
Zygosaccharomyces Bailii ◽  
Zygosaccharomyces Rouxii ◽  
High Sugar

A simple presence-absence test for detection of small numbers of osmotolerant yeasts in foods was developed. Yeast extract glucose 50 broth [consisting of 0.5% (w/w) yeast extract and 50% (w/w) glucose] was used as enrichment medium and was incubated with agitation at 30°C. The detection was done by (a) microscope and (b) streaking 0.03 ml of enrichment culture on selective yeast extract glucose 50 agar and incubation at 30°C for 5–7 d. If no yeast cells were observed under the microscope within 10 d of incubation, the product sample was judged as “free from osmotolerant yeasts.” In accordance with this method 28 strains of osmotolerant yeasts were isolated from 27 spoiled high-sugar products. Twenty-four strains were identified as Zygosaccharomyces rouxii, 2 Zygosaccharomyces bailii and 1 each as Torulaspora delbrueckii and Debaryomyces hansenii.

scholarly journals Evaluación de la diversidad de bacterias lácticas y levaduras en quesos frescos de cabra de la quebrada de Humahuaca

2015 ◽  
Vol 13 (1) ◽  
pp. 03
Author(s):  
E Gustavo Ancasi ◽  
S Maldonado ◽  
R Oliszewski
Keyword(s):  
Candida Albicans ◽  
Kluyveromyces Lactis ◽  
Debaryomyces Hansenii ◽  
Pichia Anomala ◽  
Dekkera Bruxellensis ◽  
Sabouraud Agar ◽  
Zygosaccharomyces Rouxii ◽  
Candida Magnoliae ◽  
Candida Versatilis

Los quesos frescos de cabra artesanales de la quebrada de Humahuaca son elaborados con leche cruda, cuya maduración genera sabores, aromas y texturas característicos de la región. Los objetivos de este estudio fueron identificar y caracterizar bacterias lácticas (BAL) y levaduras nativas, aisladas de quesos frescos de esta zona productora. De un total de 36 muestras sembradas en agar Sabouraud, agar MRS y M17, se obtuvieron 128 levaduras y 39 lactobacilos, los que fueron identificados fenotípicamente y evaluadas las siguientes propiedades tecnológicas: pH a la coagulación, tasa de acidificación, proteólisis en agar leche, lipólisis en agar triacetina, producción de acetoína en leche reconstituida y asimilación del citrato en agar citrato. Lb. delbruekii subsp. bulgaricus, Lb. casei subsp. pseudoplantarum, Lb. plantarum var. arabinosus, Lb. plantarum var. plantarum, Lb. casei subsp. rhamnosus, Lb. acidophilus, Lb. helveticus, Lb. fermentum, Lb. brevis var. brevis, Lactococos sp. y Enterococcus sp. fueron las bacterias lácticas identificadas. Del total de los aislamientos, 41,6% coagularon la leche en 10 horas y 33% en 5 horas. Lb. helveticus coaguló la leche a pH de 5,40 en 5 horas, hasta alcanzar un valor final de 4,16 en 24 h, mientras que Lb. delbrueckii subsp. bulgaricus y Lb. fermentum iniciaron la coagulación en 5 horas, con valores de pH iniciales de 4,81 y 4,92 hasta valores finales de 4,19 y 4,21 respectivamente. Lb. helveticus, Lb. delbrueckii subsp. bulgaricus, Lb. plantarum var. arabinosus, Lb. fermentum, Lb. casei subsp. rhamnsosus, Lb. casei subsp. pseudoplantarum, Lb. brevis var. brevis, en orden descendente, demostraron tener capacidad acidificante. Lb. fermentum y Lb. casei subsp. pseudoplantarum desarrollaron actividad proteolítica y sólo Lb. plantarum var. plantarum demostró tener actividad lipolítica. Las levaduras aisladas fueron Debaryomyces hansenii, Zygosaccharomyces rouxii, Kluyveromyces lactis, Wickerbamiela domerquiae, Dekkera bruxellensis, Candida valdiviana, Candida novakii, Dekkera bruxellensis, Candida versatilis, Candida magnoliae, Candida albicans, Pichia anómala, Dekkera anómala y Rodotorula sp. Cepas de D. hansenii, C. magnoliae, Z. rouxii,C. versatilis y K. lactis tuvieron actividad proteolítica y lipólitica, y una cepa de W. domerquiae tuvo solamente actividad proteolítica. Algunas cepas de K. lactis produjeron acetoína y D. bruxellensis y C. versatilis metabolizaron el citrato, hidrolizaron la caseína y tuvieron actividad lipolítica.  Los resultados obtenidos en este estudio muestran que la composición de las poblaciones de BAL y levadura en quesos artesanales es específica de la región. Los conocimientos adquiridos en este estudio podrían ser utilizados para la obtención de cultivos iniciadores con cepas de BAL y levaduras específicas de la región, destinados a la producción de quesos frescos con origen geográfico específico.

Effects of potassium sorbate on growth patterns, morphology, and heat resistance of Zygosaccharomyces rouxii at reduced water activity

1992 ◽  
Vol 38 (12) ◽  
pp. 1252-1259 ◽  
Author(s):  
David A. Golden ◽  
Larry R. Beuchat
Keyword(s):  
Heat Resistance ◽  
Water Activity ◽  
Growth Patterns ◽  
Potassium Sorbate ◽  
Heat Sensitivity ◽  
Growth Morphology ◽  
Zygosaccharomyces Rouxii ◽  
Inhibition Of Growth ◽  
Reduced Water ◽  
Sorbate Concentration

A study was made of the effects of potassium sorbate on growth, morphology, and heat sensitivity of an osmotolerant yeast, Zygosaccharomyces rouxii, grown in media (water activity (aw) 0.93) supplemented with glucose and sucrose. Growth patterns of Z. rouxii in YM broth supplemented with glucose (YMBG) and sucrose (YMBS) were similar, although increased potassium sorbate concentration in both media resulted in decreased growth rates. Growth in YMBS containing potassium sorbate was not as prolific as that in YMBG containing potassium sorbate. Inhibition of growth was indicated by decreased absorbance (at 600 nm) of cells grown in YMBS and in YMBG and YMBS supplemented with potassium sorbate at 600 or 1000 μg/mL. Slight decreases in cell size and alteration of cellular morphology were associated with increased potassium sorbate concentration. Plasmolysis increased as potassium sorbate concentration was elevated in YMBS but not in YMBG. Tolerance of Z. rouxii to potassium sorbate was enhanced by previous adaptation of cells in media with elevated potassium sorbate concentrations. Heat resistance of cells unadapted to potassium sorbate showed little or no increase regardless of culture age, but increased substantially in cells grown in media containing potassium sorbate, particularly YMBS. Key words: Zygosaccharomyces rouxii, potassium sorbate, glucose, sucrose, heat resistance.

Retention of Viability of Salmonella in Sucrose as Affected by Type of Inoculum, Water Activity, and Storage Temperature

2017 ◽  
Vol 80 (9) ◽  
pp. 1408-1414 ◽  
Author(s):  
Larry R. Beuchat ◽  
David A. Mann ◽  
Christine A. Kelly ◽  
Ynes R. Ortega
Keyword(s):  
Osmotic Stress ◽  
Water Activity ◽  
Storage Temperature ◽  
Low Level ◽  
High Sugar ◽  
High Inoculum ◽  
Stress Survival ◽  
Low Levels ◽  
Survival Patterns ◽  
And Storage

ABSTRACT Outbreaks of salmonellosis have been associated with consumption of high-sugar, low–water activity (aw) foods. The study reported here was focused on determining the effect of storage temperature (5 and 25°C) on survival of initially high and low levels of Salmonella in dry-inoculated sucrose (aw 0.26 ± 0.01 to 0.54 ± 0.01) and wet-inoculated sucrose (aw 0.24 ± 0.01 to 0.44 ± 0.04) over a 52-week period. With the exception of dry-inoculated sucrose at aw 0.26, Salmonella survived for 52 weeks in dry- and wet-inoculated sucrose stored at 5 and 25°C. Retention of viability was clearly favored in sucrose stored at 5°C compared with 25°C, regardless of level or type of inoculum or aw. Survival at 5°C was not affected by aw. Initial high-inoculum counts of 5.18 and 5.25 log CFU/g of dry-inoculated sucrose (aw 0.26 and 0.54, respectively) stored for 52 weeks at 5°C decreased by 0.56 and 0.53 log CFU/g; counts decreased by >4.18 and >4.25 log CFU/g in samples stored at 25°C. Inactivation rates in wet-inoculated sucrose were similar to those in dry-inoculated sucrose; however, a trend toward higher persistence of Salmonella in dry- versus wet-inoculated sucrose suggests there was a higher proportion of cells in the wet inoculum with low tolerance to osmotic stress. Survival patterns were similar in sucrose initially containing a low level of Salmonella (2.26 to 2.91 log CFU/g). The pathogen was recovered from low-inoculated sucrose stored at 5°C for 52 weeks regardless of type of inoculum or aw and from dry-inoculated sucrose (aw 0.54) and wet-inoculated sucrose (aw 0.24) stored at 25°C for 12 and 26 weeks, respectively. Results emphasize the importance of preventing contamination of sucrose intended for use as an ingredient in foods not subjected to a treatment that would be lethal to Salmonella.

Impact of mixed Torulaspora delbrueckii–Saccharomyces cerevisiae culture on high-sugar fermentation

2008 ◽  
Vol 122 (3) ◽  
pp. 312-320 ◽  
Author(s):  
Marina Bely ◽  
Philippe Stoeckle ◽  
Isabelle Masneuf-Pomarède ◽  
Denis Dubourdieu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Torulaspora Delbrueckii ◽  
High Sugar ◽  
Sugar Fermentation

scholarly journals Selection Process of a Mixed Inoculum of Non-Saccharomyces Yeasts Isolated in the D.O.Ca. Rioja

Fermentation ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 148
Author(s):  
Rocío Escribano-Viana ◽  
Lucía González-Arenzana ◽  
Patrocinio Garijo ◽  
Rosa López ◽  
Pilar Santamaría ◽  
...  
Keyword(s):  
Selection Process ◽  
Debaryomyces Hansenii ◽  
Aroma Compound ◽  
Wine Aroma ◽  
Candida Spp ◽  
Torulaspora Delbrueckii ◽  
Mixed Inoculum ◽  
Organoleptic Characteristics ◽  
Saccharomyces Yeasts ◽  
Lachancea Thermotolerans

The use of non-Saccharomyces yeasts in sequential fermentations with S. cerevisiae has been proposed to improve the organoleptic characteristics involved in the quality of wine. The present study set out to select a non-Saccharomyces inoculum from the D.O.Ca. Rioja for use in winemaking. Strains included in the study belonged to Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, Zygosaccharomyces bailii, Williopsis pratensis, Debaryomyces hansenii, Pichia kluyveri, Sporidiobolus salmonicolor, Candida spp., Cryptococcus spp. and two mixed inocula of Lachancea thermotolerans-Torulaspora delbrueckii in a 30/70 ratio. In the first stage of the process, SO2 resistance and presence of enzymatic activities related to wine aroma and wine color and fining (esterase, esterase-lipase, lipase, leucine arylamidase, valine arylamidase, cystine arylamidase, β-glucosidase, pectinase, cellulose, xylanase and glucanase) were studied. In the later stages, selection criteria such as fermentative behavior, aroma compound production or influence on phenolic compounds were studied in laboratory scale vinifications. Taking into account the results obtained in the different stages of the process, a mixed inoculum of Lachancea thermotolerans-Torulaspora delbrueckii in a 30/70 ratio was finally selected. This inoculum stood out for its high implantation capacity, the production of compounds of interest such as glycerol and lactic acid and the consequent modulation of wine acidity. Given these characteristics, the selected inoculum is suitable for the production of quality wines.

Growth Properties and Gas Formation by Yeasts Isolated from Processed Fruits in Media with Various Brix Values and Sorbic Acid Contents

1992 ◽  
Vol 55 (3) ◽  
pp. 192-197 ◽  
Author(s):  
ERICH MAIMER ◽  
MARTIN BUSSE
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Parapsilosis ◽  
Sorbic Acid ◽  
Torulaspora Delbrueckii ◽  
Zygosaccharomyces Rouxii ◽  
Gas Formation ◽  
Yeast Strains ◽  
Growth Properties ◽  
Short Time

Growth and gas formation by Saccharomyces cerevisiae (2 strains), Zygosaccharomyces rouxii (2 strains), Hansenula fabianii (2 strains), Torulaspora delbrueckii (1 strain), and Candida parapsilosis (1 strain) were studied in homogenized processed strawberries. These strawberries had 15, 30, 45, and 55° Brix in combination with 0, 50, 100, 200, 400, and 600 ppm sorbic acid. Z. rouxii showed the highest tolerance for sorbic acid, followed by S. cerevisiae and T. delbrueckii; these strains also produced gas within a short time. The highest osmotolerance was observed for Z. rouxii. Processed fruits with 55° Brix and 200 ppm sorbic acid or with 45° Brix and ≥400 ppm sorbic acid did not allow growth and gas formation by any of the yeast strains.

Detection of Zygosaccharomyces rouxii and Candida tropicalis in a High-Sugar Medium by a Metal Oxide Sensor–Based Electronic Nose and Comparison with Test Panel Evaluation

2015 ◽  
Vol 78 (11) ◽  
pp. 2052-2063 ◽  
Author(s):  
HUXUAN WANG ◽  
ZHONGQIU HU ◽  
FANGYU LONG ◽  
CHUNFENG GUO ◽  
YAHONG YUAN ◽  
...  
Keyword(s):  
Electronic Nose ◽  
Candida Tropicalis ◽  
Solid Phase ◽  
Reference Method ◽  
Test Panel ◽  
Zygosaccharomyces Rouxii ◽  
High Sugar ◽  
Yeast Strains ◽  
Total Yeast ◽  
Panel Evaluation

Osmotolerant yeasts are primarily responsible for spoilage of sugar-rich foods. In this work, an electronic nose (e-nose) was used to diagnose contamination caused by two osmotolerant yeast strains (Zygosaccharomyces rouxii and Candida tropicalis) in a high-sugar medium using test panel evaluation as the reference method. Solid-phase microextraction gas chromatography with mass spectrometry (GC-MS) was used to determine the evolution of the volatile organic compound fingerprint in the contaminated samples during yeast growth. Principal component analysis and linear discriminant analysis revealed that the e-nose could identify contamination after 48 h, corresponding to the total yeast levels of 3.68 (Z. rouxii) and 3.09 (C. tropicalis) log CFU/ml. At these levels, the test panel could not yet diagnose the spoilage, indicating that the e-nose approach was more sensitive than the test panel evaluation. Loading analysis indicated that sensors 8 and 6 were the most important for detection of these two yeasts. Based on the result obtained with the e-nose, the incubation time and total yeast levels could be accurately predicted by established multiple regression models with a correlation of greater than 0.97. In the sensory evaluation, spoilage was diagnosed after 72 h in samples contaminated with C. tropicalis and after 48 to 72 h for samples contaminated with Z. rouxii. GC-MS revealed that compounds such as acetaldehyde, acetone, ethyl acetate, alcohol, and 3-methyl-1-butanol contributed to spoilage detection by the e-nose after 48 h. In the high-sugar medium, the e-nose was more sensitive than the test panel evaluation for detecting contamination with these test yeast strains. This information could be useful for developing instruments and techniques for rapid scanning of sugar-rich foods for contamination with osmotolerant yeasts before such spoilage could be detected by the consumer.

scholarly journals Evaluation of different chemical preservatives to control Zygosaccharomyces rouxii growth in high sugar culture media

Food Control ◽  
2015 ◽  
Vol 50 ◽  
pp. 349-355 ◽  
Author(s):  
M.C. Rojo ◽  
F.N. Arroyo López ◽  
M.C. Lerena ◽  
L. Mercado ◽  
A. Torres ◽  
...  
Keyword(s):  
Culture Media ◽  
Zygosaccharomyces Rouxii ◽  
High Sugar ◽  
Chemical Preservatives

Relationships between sucretolerance and salinotolerance in bacteria from hypersaline environments and their implications for the exploration of Mars and the icy worlds

2016 ◽  
Vol 16 (2) ◽  
pp. 156-162 ◽  
Author(s):  
Casper Fredsgaard ◽  
Donald B. Moore ◽  
Amer F. Al Soudi ◽  
James D. Crisler ◽  
Fei Chen ◽  
...  
Keyword(s):  
Water Activity ◽  
Science Studies ◽  
Differentially Expressed ◽  
Food Science ◽  
Bacterial Isolates ◽  
Hypersaline Environments ◽  
High Sugar ◽  
Microbial Isolates

AbstractThe most extremely osmotolerant microbial isolates are fungi from high-sugar environments that tolerate the lowest water activity (0.61) for growth yet reported. Studies of osmotolerant bacteria have focused on halotolerance rather than sucretolerance (ability to grow in high sugar concentrations). A collection of salinotolerant (≥10% NaCl or ≥50% MgSO4) bacterial isolates from the Great Salt Plains of Oklahoma and Hot Lake in Washington were screened for sucretolerance in medium supplemented with ≥50% fructose, glucose or sucrose. Tolerances significantly differed between solutes, even though water activities for saline media (0.92 and 0.85 for 10 and 20% NaCl Salt Plains media, respectively) were comparable or lower than water activities for high-sugar media (0.93 and 0.90 for 50 and 70% sucrose artificial nectar media, respectively). These specific solute effects were differentially expressed among individual isolates. Extrapolating the results of earlier food science studies with yeasts at high sugar concentrations to bacteria in salty environments with low water activity should be done with caution. Furthermore, the discussion of habitable Special Regions on Mars and the icy worlds should reflect an understanding of specific solute effects.

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