scholarly journals Influence of temperature, humidity, and diluent type on survival of Salmonella spp. on the surface of raw tomatoes

10.5219/1121 ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 325-330
Author(s):  
Oleksandr Tokarskyy ◽  
Keith Schneider
Keyword(s):  
Relative Humidity ◽  
Storage Period ◽  
High Humidity ◽  
Salmonella Spp ◽  
Influence Of Temperature ◽  
Pathogen Elimination ◽  
Peptone Water ◽  
Low Humidity ◽  
Fresh Tomato ◽  
The U.S

Tomatoes are an important commodity, placing fourth among most popular vegetables in the U.S. However, fresh tomatoes lack a final pathogen elimination step and have been implicated in Salmonella-related outbreaks. The purpose of the study was to evaluate survival of Salmonella post-drying in three diluents on the surface of green mature tomatoes at 12 °C or 25 °C. Additionally, low and high air relative humidity influence was evaluated at 25 °C on pathogen survival. A five Salmonella rifampin-resistant strain cocktail was double-washed in buffered peptone water (BPW) and resuspended in 0.1% peptone, BPW, or fresh tomato serum. Inoculum (0.1 mL) was allowed to dry on the surface of tomatoes. For study I, tomatoes were placed in 12 °C and 25 °C incubators with no humidity control and sampled on days 0, 1, 3, and 5. For study II, tomatoes were sampled on days 0, 1 (biosafety hood storage) and on day 5 after storage in two 25 oC incubators (low and high relative humidity). Salmonella was recovered from tomatoes (20 mL BPW) and plated (TSA-rif80, 37 °C, 48 hours). Post-drying Salmonella counts (ca. 4.5 – 5.0 log10 CFU.mL-1) remained at 4.03 and 4.40 log10 CFU.mL-1 in serum after 5 days of storage at 12 °C and 25 °C, respectively. Conversely, corresponding counts in BPW and peptone were lower at ca. 1.4 to 1.8 and 2.2 to 2.8 log units at 12 °C and 25 °C, respectively. At low humidity, post-drying Salmonella counts showed highest decline for peptone (final 1.98 log10 CFU.mL-1) compared to BPW (3.79 log10 CFU.mL-1) and tomato serum (4.75 log10 CFU.mL-1) on day 5. Counts declined rapidly to 0.03, 0.56, and 0.44 log10 CFU.mL-1 for peptone, BPW, and tomato serum, respectively, at high humidity on day 5. To summarize, it was shown that increased solutes have protective effect on Salmonella in desiccated conditions, while high humidity storage causes accelerated death of stationary culture within five days storage period.

STUDIES OF THE AGING OF CONIDIA OF MONILINIA FRUCTICOLA (WINT.) HONEY: I.GERMINATION RATES AND LONGEVITY

1957 ◽  
Vol 35 (5) ◽  
pp. 635-645 ◽  
Author(s):  
S. H. Z. Naqvi ◽  
H. M. Good
Keyword(s):  
Relative Humidity ◽  
Storage Temperature ◽  
Potato Dextrose Agar ◽  
Monilinia Fructicola ◽  
High Humidity ◽  
Percentage Germination ◽  
Low Humidity ◽  
Nutrient Solutions

Conidia of Monilinia fructicola (Wint.) Honey were stored 1–10 months at temperatures of 5°, 25°, and 35 °C. and at constant relative humidities approximating 0, 15, 45, 75, and 90%. The germination of these spores was tested on potato dextrose agar containing 6% glucose, and curves of the percentage germination against time are given for representative samples.A pronounced delay in germination developed under all conditions of storage. The rate at which this delay developed was virtually independent of the storage temperature. All spore samples gave 100% germination after 3 months but only those at 5 °C. gave; any germination after 10 months. Storage in a relative humidity of 75% gave the best preservation of spore vigor, there being evidence in other conditions of either high humidity or low humidity injury. Of the nutrient solutions tested, glucose was the only one which gave substantially better germination than water, the effect being most marked on spores stored for some months at high humidity. With glucose, such spores sometimes germinated faster than those stored at intermediate humidities.

scholarly journals High Relative Humidity after Ethylene Gassing is Important to Banana Fruit Quality

1995 ◽  
Vol 5 (2) ◽  
pp. 150-151 ◽  
Author(s):  
Sylvia M. Blankenship ◽  
Robert W. Herdeman
Keyword(s):  
Relative Humidity ◽  
Fruit Quality ◽  
High Relative Humidity ◽  
High Humidity ◽  
Banana Fruit ◽  
Fruit Firmness ◽  
Compression Injury ◽  
Peel Color ◽  
Before And After ◽  
Low Humidity

Bananas were held at 18C in all possible combinations of 65%, 75%, or 95% relative humidity (RH) before and after gassing with ethylene. Peel color, fruit firmness, starch loss, compression injury to peel and pulp, and overall peel scarring were measured. Peels were greener and the fruit were slightly firmer when fruit were held in the higher humidity combinations, particularly when the humidity was high after gassing with ethylene. Starch loss was not different among humidity treatments. Overall peel scarring was about twice as severe with 65% RH compared to 95% RH during the ripening phase. Low humidity before ethylene gassing had little effect on overall scarring. There were some instances where humidity had a significant effect on compression injury; high humidity caused less injury, but the effect was inconsistent.

COLOUR OF MEAT: II. EFFECT OF DESICCATION ON THE COLOUR OF CURED PORK

1939 ◽  
Vol 17d (2) ◽  
pp. 29-34 ◽  
Author(s):  
C. A. Winkler
Keyword(s):  
Relative Humidity ◽  
Colour Change ◽  
Storage Period ◽  
Moisture Loss ◽  
Influence Of Temperature ◽  
Dry Air ◽  
Intensity Changes ◽  
Influence Of Temperature On

In the absence of air, a linear relation, independent of temperature, was observed between moisture loss and colour change. The change was mainly one of intensity, and was reversible. In air, irrespective of its humidity, changes in both intensity and quality of colour occurred, but no definite relation was found between changes in humidity and colour quality for different samples. In saturated air, intensity changes became complete in the early part of the storage period, but the enhanced changes in air of lower humidity continued to increase. No influence of temperature on the rate of colour change was observed in dry air or in air of 60% relative humidity.

Some Effects of Humidity on the Translocation of 2,4,5-T in Bean Plants

Weed Science ◽  
1970 ◽  
Vol 18 (3) ◽  
pp. 396-398 ◽  
Author(s):  
Eddie Basler ◽  
Fred W. Slife ◽  
John W. Long
Keyword(s):  
Acetic Acid ◽  
Relative Humidity ◽  
Nutrient Solution ◽  
Leaf Tissue ◽  
Phloem Transport ◽  
High Humidity ◽  
Plant Parts ◽  
Bean Plants ◽  
Low Humidity ◽  
Nutrient Solutions

The effect of humidity on the rate and direction of translocation of stem-injected (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) in bean (Phaseolus vulgaris L., var. Stringless Green-pod) seedlings was determined. A total of 0.75 μg of 14C-labeled 2,4,5-T was injected into the stem with a 1-μl syringe pipette. Translocation was determined by assaying the nutrient solution and plant parts for 14C. High relative humidities enhanced downward translocation to roots and nutrient solutions. About 41% of the applied 2,4,5-T was found in the nutrient solution after 2 days' treatment at about 95% relative humidity while only 23% was found when treatment was conducted at 20% relative humidity. Low humidity during treatment caused much more 2,4,5-T to be translocated upward to the primary leaves and young shoots of the seedlings and this effect was more pronounced in plants which were grown in low humidity prior to treatment. The results confirm the conclusions of others and show that the increased basipetal phloem transport of herbicides in plants under high humidity is not due to an effect on penetration of herbicides in leaf tissue.

scholarly journals Colonization of Tomatoes by Salmonella Montevideo Is Affected by Relative Humidity and Storage Temperature†

2007 ◽  
Vol 70 (1) ◽  
pp. 30-34 ◽  
Author(s):  
MONTSERRAT H. ITURRIAGA ◽  
MARK L. TAMPLIN ◽  
EDUARDO F. ESCARTÍN
Keyword(s):  
Relative Humidity ◽  
Lycopersicon Esculentum ◽  
Pathogenic Bacteria ◽  
Storage Temperature ◽  
High Humidity ◽  
Scanning Electron Micrographs ◽  
Peptone Water ◽  
Growth Promoting ◽  
And Storage ◽  
Scanning Electron

The influences of the relative humidity (RH) and storage temperature on the colonization of tomato surfaces by Salmonella Montevideo were studied. Red, ripe tomatoes (Lycopersicon esculentum) were spot inoculated in three separate trials with 100 μl (approximately 106 CFU) of Salmonella Montevideo and stored for 90 min at 22°C under 97% RH to facilitate attachment of cells to the blossom end of tomato surfaces. Following this attachment step, tomatoes were washed to remove loosely adhered cells and then stored at 22 or 30°C for up to 10 days under RH of 60, 75, 85, or 97%. At 0, 0.4, 1, 4, 7, and 10 days of storage, three tomatoes were individually hand massaged in 50 ml of 0.1% peptone water and the washes were separately analyzed to enumerate populations of Salmonella Montevideo. The number of Salmonella Montevideo cells attached after 90 min at 22°C was 3.8 log CFU per tomato; this level was determined to be the initial colonizing population. After 10 days of storage at 30°C, the Salmonella Montevideo population increased to 0.7, 1.0, 1.2, and 2.2 log CFU per tomato at 60, 75, 85, and 97% RH, respectively. A similar trend was observed at 22°C, although populations were lower than at 30°C. Scanning electron micrographs of tomato cuticles after storage revealed a well-defined biofilm containing bacteria. These findings reinforce the importance of maintaining stored tomatoes at temperatures that do not support growth of pathogenic bacteria and demonstrate the growth-promoting effects of high humidity.

INFLUENCE OF WEATHER ON FLIGHT ACTIVITY OF PARASITIC HYMENOPTERA

1964 ◽  
Vol 42 (6) ◽  
pp. 1133-1141 ◽  
Author(s):  
J. A. Juillet
Keyword(s):  
Light Intensity ◽  
Wind Velocity ◽  
Insect Pests ◽  
Flight Activity ◽  
High Humidity ◽  
Forest Insect ◽  
Influence Of Temperature ◽  
Light Rain ◽  
Parasitic Hymenoptera ◽  
Low Humidity

The influence of temperature, relative humidity, wind velocity, light intensity, and precipitation on the flight activity of diurnal ichneumonids and braconids is discussed. Light rain stimulates flight activity, but light intensity does not affect it. Ichneumonids are most active at moderate temperature, high humidity, and low wind velocity, while braconids are most active at high temperature, low humidity, and low wind velocity. The optimum weather for maximum flight activity coincides with the fact that ichneumonids predominate on forest insect pests, and braconids on agricultural insect pests.

scholarly journals High Temperatures Decrease the Flight Capacity of Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 394
Author(s):  
Carlos A. Antolinez ◽  
Tobias Moyneur ◽  
Xavier Martini ◽  
Monique J. Rivera
Keyword(s):  
Relative Humidity ◽  
High Temperatures ◽  
Insect Pest ◽  
The United States ◽  
Diaphorina Citri ◽  
Long Distance ◽  
Flight Duration ◽  
Custom Made ◽  
Flight Capacity ◽  
Low Humidity

Diaphorina citri Kuwayama (Hemiptera: Liviidae), commonly known as Asian citrus psyllid (ACP), is an invasive insect pest and the vector of the bacterium causing Huanglongbing (HLB), a lethal disease of citrus. In the United States, ACP has been established in all citrus-producing zones, all of which have different environmental conditions. The spread of ACP and, more importantly, HLB, has progressed differently depending on the state, with more rapid spread in Florida and Texas than in California. Climatic variations between the regions are likely a strong factor in the difference in the rate of spread. Despite this, it is unknown how the flight capacity of D. citri is influenced by high temperatures (>30 °C) and subsequently, low humidity experienced in California but not in Texas or Florida. In this study, by using a custom-made, temperature-controlled flight mill arena, we assessed the effect of high temperatures on the flight capacity and flight propensity of D. citri under low (20–40%) and high (76–90%) relative humidity conditions. We found that temperature and humidity influence the propensity to engage in short or long-distance flight events. Psyllids exposed to temperatures above 43 °C only performed short flights (˂60 s), and a high relative humidity significantly decrease the proportion of long flights (≥60 s) at 26 and 40 °C. The flight capacity for insects who engaged in short and long flights was significantly affected by temperature but not by humidity. For long flyers, temperature (in the 26–43 °C range) was negatively correlated with distance flown and flight duration. The most favorable temperature for long dispersion was 26 °C, with suboptimal temperatures in the range of 32–37 °C and the least favorable temperatures at 40 and 43 °C. In conclusion, D. citri is able to fly in a broad range of temperatures and efficiently fly in high and low humidity. However, temperatures above 40 °C, similar to those experienced in semi-arid environments like Southern California or Arizona, are detrimental for its flight capacity.

Influence of temperature and relative humidity on early bond strengths to dentine

1995 ◽  
Vol 23 (1) ◽  
pp. 41-45 ◽  
Author(s):  
M.F. Burrow ◽  
Y. Taniguchi ◽  
T. Nikaido ◽  
M. Satoh ◽  
N. Inai ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Influence Of Temperature ◽  
Bond Strengths

High Humidity, Low Humidity, and Mist Therapy for Croup

JAMA ◽  
2006 ◽  
Vol 296 (4) ◽  
pp. 393
Author(s):  
Richard Gabor
Keyword(s):  
High Humidity ◽  
Low Humidity
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