Inactivation of Saccharomyces cerevisiae and Polyphenoloxidase in Mango Nectar Treated with UV Light

2006 ◽  
Vol 69 (2) ◽  
pp. 362-368 ◽  
Author(s):  
JOSÉ A. GUERRERO-BELTRÉN ◽  
GUSTAVO V. BARBOSA-CÉNOVAS
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Uv Light ◽  
Storage Period ◽  
Microbial Load ◽  
Microbial Count ◽  
Uv Treatment ◽  
Log Reduction ◽  
First Order Kinetics ◽  
Yellow Orange ◽  
Entire Storage Period

Fresh mango nectar was processed by UV light at five flow rates (0.073 to 0.451 liter/min) and five UV light doses (75 to 450 kJ/m2) to evaluate total microbial load, Saccharomyces cerevisiae survival, and polyphenoloxidase activity. UV systems containing an inner mercury lamp (254 nm) each with intensity of 25 mW/cm2 were used as germicidal sources. In addition, mango nectar was treated for 15 min at 0.073 and 0.451 liter/min, stored at 3°C, and evaluated periodically for total microbial count, yeast count, color, and polyphenoloxidase activity. The first-order kinetics modeling found that DUV-values in mango nectar ranged from 27.9 to 10.9 min (R2 > 0.950) and 26.0 to 11.8 min (R2 > 0.962) for total microbial count and yeast count, respectively. The maximum log reduction (CFU per milliliter) was 2.71 and 2.94 for total microbial count and yeast count, respectively, after 30 min of UV treatment at 0.451 liter/min. DUV-values ranging from 156 to 204 min were observed for polyphenoloxidase activity. The remaining polyphenoloxidase activity after 30 min of UV treatment at 0.451 liter/min was 19 ± 4%. Initial microbial load and yeast in stored mango nectar were reduced in the range 2.86 to 3.41 and 1.82 to 1.97 log (CFU/ml) cycles, respectively. No substantial microbial growth was observed prior to 20 days of storage. Averages of 1,055 ± 32, 803 ± 32, and 710 ± 37 enzyme activity units were observed in mango nectar UV processed at 0, 0.073, and 0.451 liter/min, respectively, during the entire storage period. However, mango nectar treated at 0.073 and 0.451 liter/min maintained a yellow and yellow-orange color, respectively, after 26 days of storage.

Use of UV Light for the Inactivation of Listeria monocytogenes and Lactic Acid Bacteria Species in Recirculated Chill Brines

2008 ◽  
Vol 71 (3) ◽  
pp. 629-633 ◽  
Author(s):  
K. M. GAILUNAS ◽  
K. E. MATAK ◽  
R. R. BOYER ◽  
C. Z. ALVARADO ◽  
R. C. WILLIAMS ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Thermal Processing ◽  
Uv Light ◽  
Light Exposure ◽  
Meat Products ◽  
Uv Treatment ◽  
Bacterial Populations ◽  
Log Reduction

Ready-to-eat meat products have been implicated in several foodborne listeriosis outbreaks. Microbial contamination of these products can occur after thermal processing when products are chilled in salt brines. The objective of this study was to evaluate UV radiation on the inactivation of Listeria monocytogenes and lactic acid bacteria in a model brine chiller system. Two concentrations of brine (7.9% [wt/wt] or 13.2% [wt/wt]) were inoculated with a ~6.0 log CFU/ml cocktail of L. monocytogenes or lactic acid bacteria and passed through a UV treatment system for 60 min. Three replications of each bacteria-and-brine combination were performed and resulted in at least a 4.5-log reduction in microbial numbers in all treated brines after exposure to UV light. Bacterial populations were significantly reduced after 5 min of exposure to UV light in the model brine chiller compared with the control, which received no UV light exposure (P < 0.05). The maximum rate of inactivation for both microorganisms in treated brines occurred between minutes 1 and 15 of UV exposure. Results indicate that in-line treatment of chill brines with UV light reduces the number of L. monocytogenes and lactic acid bacteria.

scholarly journals Quantitative Microbiological Analysis of Artisanal Stretched Cheese Manufacture

2021 ◽  
Author(s):  
Veronika Lehotová ◽  
Veronika Antálková ◽  
Alžbeta Medveďová ◽  
Ľubomír Valík
Keyword(s):  
Early Stage ◽  
Storage Period ◽  
Coliform Bacteria ◽  
Microbiological Analysis ◽  
E Coli ◽  
Log Reduction ◽  
Milk Coagulation ◽  
Entire Storage Period ◽  
Stretching Process ◽  
Cheese Production

To evaluate the behaviour of the relevant microbial populations during stretched cheese production, the quantitative microbiological analysis was performed during the critical steps of the preparation. The obtained data distributions proved statistically significant increases in all indicators, on average by 4.55 ± 0.64 log CFU/g of presumptive lactococci counts, 4.06 ±0.61 of lactobacilli, 1.53 ± 0.57 log CFU/g of coliforms, 2.42 ± 0.67 log CFU/g of Escherichia coli, 1.53 ± 0.75 log CFU/g of yeasts and moulds, and 0.99 ± 0.27 log CFU/g of presumptive Staphylococcus aureus, from the early stage of milk coagulation until curd ripening (0–24 h). The following steaming/stretching process caused reductions in viable counts with the most significant inactivation effect on coliform bacteria, including E. coli (-4.0 ± 1.0 log CFU/g). Total viable counts and yeasts and moulds showed 2 and almost 3 log reduction (-2.2 ± 1.1 log CFU/g and -2.6 ± 0.9 log CFU/g), respectively. The lowest decreases in presumptive S. aureus counts were estimated at the level of -1.50 ± 0.64 log CFU/g. The counts of yeasts and moulds showed the best indicatory function during the entire storage period of vacuum-packaged cheeses at 6 °C.

scholarly journals 514 Influence of Storage and Sanitizing Protocols on the Physiology of Fresh-cut Watermelon

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 483D-483
Author(s):  
Jorge M. Fonseca ◽  
James W. Rushing ◽  
Robert F. Testin
Keyword(s):  
Uv Light ◽  
Chilling Injury ◽  
Microbial Count ◽  
Uv Treatment ◽  
Random Occurrence ◽  
Initial Reduction ◽  
Fresh Cut ◽  
Increasing Temperature ◽  
Better Than

Fresh-cut watermelon cubes stored at selected temperatures within the range of 1.1 to 14.5 °C had decreasing quality shelf life corresponding with increasing temperature. At lower temperatures there was a random occurrence of chilling injury symptoms in some cubes that was associated with the section of watermelon from which the cubes were cut. Cubes removed from the top side of the intact watermelon fruit were more susceptible to chilling injury than cubes from other sectors of the fruit. Sanitizing cubes with chlorine (40 ul/l) or ozone (0.04 μL/L) solutions caused an initial reduction in microbial count, but, during storage, the effect diminished and became insignificant compared to controls. Overall quality was lower in cubes receiving aqueous sanitizing treatments, possibly due to mechanical injury occurring during centrifugation to remove excess solution. Overall quality of cubes exposed to UV light (≈250 nm for 1 to 5 min) was better than cubes receiving aqueous sanitizing treatment. The effectiveness of UV treatment in reducing microbial load was dependent on the amount of cube surface exposed to the light. The results emphasize the importance of preventing microbial contamination during processing of fresh-cut watermelon.

scholarly journals Influence of Storage and Sanitizing Protocols on the Physiology of Fresh-Cut Watermelon

HortScience ◽  
2000 ◽  
Vol 35 (4) ◽  
pp. 567D-567c
Author(s):  
Jorge M. Fonseca ◽  
James W. Rushing ◽  
Robert F. Testin
Keyword(s):  
Uv Light ◽  
Chilling Injury ◽  
Microbial Count ◽  
Uv Treatment ◽  
Random Occurrence ◽  
Initial Reduction ◽  
Fresh Cut ◽  
Increasing Temperature ◽  
Better Than

Fresh-cut watermelon cubes stored at selected temperatures within the range of 1.1 to 14.5 °C had decreasing quality shelf life corresponding with increasing temperature. At lower temperatures there was a random occurrence of chilling injury symptoms in some cubes that was associated with the section of watermelon from which the cubes were cut. Cubes removed from the top side of the intact watermelon fruit were more susceptible to chilling injury than cubes from other sectors of the fruit. Sanitizing cubes with chlorine (40 μL·L–1) or ozone (0.04 μL·L–1) solutions caused an initial reduction in microbial count but during storage the effect diminished and became insignificant compared to controls. Overall quality was lower in cubes receiving aqueous sanitizing treatments, possibly due to mechanical injury occurring during centrifugation to remove excess solution. Overall quality of cubes exposed to UV light (≈250 nm for 1–5 min) was better than cubes receiving aqueous sanitizing treatment. The effectiveness of UV treatment in reducing microbial load was dependent on the amount of cube surface exposed to the light. The results emphasize the importance of preventing microbial contamination during processing of fresh-cut watermelon.

Effect of Nonthermal, Conventional, and Combined Disinfection Technologies on the Stability of Human Adenoviruses as Fecal Contaminants on Surfaces of Fresh Ready-to-Eat Products

2016 ◽  
Vol 79 (3) ◽  
pp. 454-462 ◽  
Author(s):  
ANGELIKI BIRMPA ◽  
MARIA BELLOU ◽  
PETROS KOKKINOS ◽  
APOSTOLOS VANTARAKIS
Keyword(s):  
Treatment Time ◽  
Uv Light ◽  
Foodborne Diseases ◽  
Uv Treatment ◽  
Viral Inactivation ◽  
Viral Origin ◽  
Infectious Dose ◽  
Human Adenoviruses ◽  
Log Reduction ◽  
The Stability

ABSTRACT Over one-half of foodborne diseases are believed to be of viral origin. The ability of viruses to persist in the environment and fresh produce, as well as their low infectious dose, allows even a small amount of contamination to cause serious foodborne problems. Moreover, the consumer's demands for fresh, convenient, and safe foods have prompted research into alternative food disinfection technologies. Our study focuses on viral inactivation by both conventional and alternative nonthermal disinfection technologies on different fresh ready-to-eat food products. The use of chlorine, as well as that of nonthermal technologies such as UV light and ultrasound (US), was tested for different treatment times. UV nonthermal technology was found to be more effective for the disinfection of human adenoviruses (hAdVs) compared with US, achieving a log reduction of 2.13, 1.25, and 0.92 for lettuce, strawberries, and cherry tomatoes, respectively, when UV treatment was implemented for 30 min. US treatment for the same period achieved a log reduction of 0.85, 0.53, and 0.36, respectively. The sequential use of US and UV was found to be more effective compared with when the treatments were used separately, for the same treatment time, thus indicating a synergistic effect. In addition, human adenoviruses were inactivated sooner, when chlorine treatment was used. Therefore, the effect of each disinfection method was dependent upon the treatment time and the type of food.

scholarly journals Quantitative Microbiological Analysis of Artisanal Stretched Cheese Manufacture

2021 ◽  
Vol 11 (6) ◽  
pp. 2680
Author(s):  
Veronika Lehotová ◽  
Veronika Antálková ◽  
Alžbeta Medveďová ◽  
Ľubomír Valík
Keyword(s):  
Early Stage ◽  
Storage Period ◽  
Coliform Bacteria ◽  
Microbiological Analysis ◽  
E Coli ◽  
Log Reduction ◽  
Milk Coagulation ◽  
Yeasts And Molds ◽  
Entire Storage Period ◽  
Cheese Production

To evaluate the behavior of the relevant microbial populations during stretched cheese production, quantitative microbiological analysis was performed during the critical steps of the preparation. The obtained data distributions proved statistically significant increases in all indicators, on average by 4.55 ± 0.64 log CFU/g of presumptive lactococci counts, 4.06 ± 0.61 of lactobacilli, 1.53 ± 0.57 log CFU/g of coliforms, 2.42 ± 0.67 log CFU/g of Escherichia coli, 1.53 ± 0.75 log CFU/g of yeasts and molds, and 0.99 ± 0.27 log CFU/g of presumptive Staphylococcus aureus, from the early stage of milk coagulation until curd ripening (0–24 h). The following steaming/stretching process caused reductions in viable counts with the most significant inactivation effect on coliform bacteria, including E. coli (−4.0 ± 1.0 log CFU/g). Total viable counts and yeasts and molds showed 2 and almost 3 log reduction (−2.2 ± 1.1 log CFU/g and −2.6 ± 0.9 log CFU/g), respectively. The lowest decreases in presumptive S. aureus counts were estimated at the level of −1.50 ± 0.64 log CFU/g. The counts of yeasts and molds showed the best indicatory function during the entire storage period of vacuum-packaged cheeses at 6 °C.

Optimization of processing conditions of milk “coagulum” rings and the effect of incorporation of extenders on their quality and storage stability under ambient temperature conditions

2018 ◽  
Vol 120 (11) ◽  
pp. 2645-2659
Author(s):  
H. Lalawmpuii ◽  
Geeta Chauhan ◽  
Sanjod K. Mendiratta ◽  
Tarun Pal Singh ◽  
Bhanu Pratap Singh ◽  
...  
Keyword(s):  
Milk Fat ◽  
Storage Period ◽  
Banana Peel ◽  
Microbial Count ◽  
Processing Conditions ◽  
Total Dietary Fiber ◽  
Content Type ◽  
Oxidation Parameter ◽  
Banana Peel Powder ◽  
Entire Storage Period

PurposeThe purpose of this paper is to optimize the processing conditions of ready-to-eat (RTE) milk “coagulum” rings.Design/methodology/approachMilk “coagulum” rings were prepared from milk coagulum. Milk at four different level of milk fat (0.1, 1.5, 3 and 4.5 percent) were used to obtain milk coagulum of four different fat level for preparing milk “coagulum” rings. Unripe banana powder (UPB) and banana peel powder (BPP) were incorporated at three different levels separately. The incorporation levels were also optimized to be 11 percent for UPB and 6 percent for BPP on the basis of sensory evaluation.FindingsThe yield, ash, moisture and total dietary fiber content of products with optimized level of UPB and BPP were significantly higher as compared to control while the protein and fat contents were lower. Incorporation of extenders resulted in a significant reduction in the color value of the treated products. The water activity was highest forT2and lowest for control at the end of 42 days. TBARS as lipid oxidation parameter was highest for control and the microbial count was comparable inT1andT2where as it was higher in control. The sensory scores of the control was higher than the two treated products during the entire storage period.Originality/valueThe shelf stable RTE milk coagulum-based snack using 1.5 percent fat can provide a nutritious, palatable and healthy product to the consumers.

UV Irradiation of Shell Eggs: Effect on Populations of Aerobes, Molds, and Inoculated Salmonella typhimurium

1997 ◽  
Vol 60 (6) ◽  
pp. 639-643 ◽  
Author(s):  
FUENG-LIN KUO ◽  
JOHN B. CAREY ◽  
STEVEN C. RICKE
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Radiation ◽  
Uv Light ◽  
The Other ◽  
Uv Exposure ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Uv Treatment ◽  
Shell Eggs

The effects were investigated of 254-nm UV radiation on populations of Salmonella typhimurium, aerobes, and molds on the shells of eggs. In the first experiment, the CFU of attached S. typhimurium cells on unwashed clean shell eggs were determined after 0, 1, 3, 5, and 7 min of UV treatment (620 μW/cm2) on both ends of the egg. All UV treatments significantly reduced S. typhimurium CFU (P < .01). UVtreatment (620 μW/cm2) in 1-min alternating light and dark cycles for 5 min (three light and two dark) was compared to 0, 3, and 5 min of UV treatment. No significant differences in microbial populations were observed among light and dark cycles and the other UV treatments. In a subsequent experiment, the same UV treatments were utilized to evaluate photoreactivation. After UV exposure, eggs were exposed to 1 h of fluorescent light or I h of darkness or cultured immediately. S. typhimurium CFU were significantly (P < .01) reduced by the UV treatments. However, no significant differences between microbial populations exposed to UV treatment and UV radiation plus photoreactivation were detected. For studies of aerobic bacteria and molds, different UV treatment times (0, 15, and 30 min) at the intensity of 620 μW/cm2 and different intensities (620, 1350, and 1720 μW/cm2) for 15 min were evaluated. Mold CFU per egg were either 0 or 1 for all UV treatments and a 99% reduction of CFU of aerobic bacteria per egg were observed for all UV treatments. It appears from these studies that UV light can significantly reduce populations of S. typhimurium, aerobes, and molds on shell eggs.

scholarly journals DELETIONS OF THE ISO-1-CYTOCHROME c AND ADJACENT GENES OF YEAST: DISCOVERY OF THE OSM1 GENE CONTROLLING OSMOTIC SENSITIVITY

Genetics ◽  
1978 ◽  
Vol 89 (4) ◽  
pp. 653-665
Author(s):  
Arjun Singh ◽  
Fred Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Uv Light ◽  
Yeast Saccharomyces Cerevisiae ◽  
Osmotic Sensitivity ◽  
Inhibition Of Growth

ABSTRACT Some of the deletions in the yeast Saccharomyces cerevisiae that encompass the CYC1 gene, which determines iso-1-cytochrome c, extend into the OSM1 gene, causing inhibition of growth on hypertonic media, and into the RAD7 gene, causing sensitivity to UV light. Two deletions (cyc1-363 and cyc1-367) encompass only the CYC1 gene, two deletions (cyc1-366 and cyc1-368) encompass the CYC1 and OSM1 genes, three deletions (cyc1-1, cyc1-364 and cyc1-365) encompass the CYC1, OSM1 and RAD7 genes, while none of the deletions extend into the closely linked SUP4 gene.

COMPARATIVE EVALUATION OF YOGHURT SAMPLES FROM GOATS AND COWS MILK AND COMMERCIAL RETAIL OUTLET

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
V. A. Obatolu ◽  
E. A. Adebowale ◽  
F. Omidokun ◽  
E. O. Farinde
Keyword(s):  
Goat Milk ◽  
Storage Period ◽  
Total Solid ◽  
Cow Milk ◽  
Microbial Count ◽  
Significant Drop ◽  
Overall Acceptability ◽  
Count Range ◽  
Significant Difference ◽  
Mineral Acidity

This paper compared the chemical (Proximate and mineral), acidity, microbial count and organoleptic properties of yoghurt samples produced from Nigeria locally bred goat and cow milk with commercially retail yoghurt during 14days of refrigerated storage. Yoghurt production was conducted by inoculation of the milk samples at 43oC for 6hrs with 2% of streptococcus thermophillus and lactobacillus bulgarus active culture. The total ash content of yoghurt ranges from 0.23g/100g in the commercial yoghurt sample to 0.84g/100g in yoghurt from goat  milk which is considered significantly higher than that observed for yoghurt from cow milk. The commercially retail yoghurt had a significantly higher (P < 0.05) total solid matter than yoghurt from goat and cow milk. Calcium and phosphorus contents were significantly (P < 0.05) lowest in the commercial yoghurt (0.28%) to a significant higher value of 0.28% in goat milk. A statisitically significant drop in pH values was observed in the commercial yoghurt sample after one and two week storage compared to yoghurt from goat and cow milk. High lactic acid bacteria were observed in yoghurt from cow milk with lactococci group being higher than the lactobacilli group throughout the storage period. The yeast count range from a significant low (P < 05) value of 2.22 cfu/ml-1 in commercial yoghurt sample to 3.22 and 3.24 in goat and cow milk respectively on day zero of storage. By the 7days of storage, the commercially retail yoghurt was significant (P < 0.05) least desirable with respect to colour, taste and overall acceptability while there was no significant difference in the consistency of all the yoghurt samples.

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