Associations between Weather and Microbial Load on Fresh Produce Prior to Harvest

2015 ◽  
Vol 78 (4) ◽  
pp. 849-854 ◽  
Author(s):  
MICHELLE WARD ◽  
RADHIKA DHINGRA ◽  
JUSTIN V. REMAIS ◽  
HOWARD H. CHANG ◽  
LYNETTE M. JOHNSTON ◽  
...  
Keyword(s):  
Fresh Produce ◽  
Microbial Load ◽  
Weather Data ◽  
Plate Count ◽  
Sample Collection ◽  
Microbial Indicators ◽  
Average Temperature ◽  
Temperature And Precipitation ◽  
Aerobic Plate Count ◽  
Relationship Of

Contaminated produce causes approximately 1 million cases of foodborne illness and 1 billion dollars in damages to the U.S. economy annually. The environmental conditions, especially weather, that influence the inoculation, proliferation, and dispersal of microbial load on produce are not well understood. Using a mixed models approach, we examined the relationship of temperature and precipitation to microbial indicators of contamination on fresh produce on the farm over a week-long period prior to harvest. Between 2000 and 2002, we assayed for four microbial indicators of contamination (aerobic plate count, Enterococcus, total coliforms, and Escherichia coli) on 10 produce types in 15 fields in the southern United States. The sample collection times varied, with most occurring between January and May. We collected hourly weather data for the corresponding time period and location. Our results indicated that there was a significant association between the average daily temperature (20°C) and both log aerobic plate count (e.g., an increase of 0.074 log CFU/g [standard error {SE}, 0.023] per °C increase in weekly average temperature) and log Enterococcus (e.g., an increase of 0.15 log CFU/g [SE, 0.031] per °C increase in weekly average temperature) for approximately 5 days prior to sample collection. Daily total precipitation was significantly associated with log coliforms on 2 days (~0.11 log CFU/g [SE, 0.06] per mm of precipitation) during the week-long lag period prior to harvest. Our results suggest that microbial indicator concentrations may increase as the temperature increases. Precipitation may have a positive but complex relationship with microbial indicators, as precipitation may create moist conditions conducive to bacterial growth, spread contamination onto the field, or wash contamination off of the plant.

scholarly journals Effect of Pulsed Ultraviolet Light on Natural Microbial Load and Antioxidant Properties of Fresh Blueberries

2018 ◽  
Vol 6 (6) ◽  
pp. 733
Author(s):  
Senem Guner ◽  
Zeynal Topalcengiz
Keyword(s):  
Enzyme Activity ◽  
Antioxidant Capacity ◽  
Antioxidant Enzyme ◽  
Antioxidant Properties ◽  
Antioxidant Enzyme Activity ◽  
Microbial Load ◽  
Plate Count ◽  
Light Illumination ◽  
Sod Activity ◽  
Aerobic Plate Count

Blueberries have been drawn more attention in recent years for their antioxidant capacities and proposed health benefits. Pulsed ultraviolet (PUV) light is known for its disinfection effects on the surface of fresh fruits. This study’s aim was to examine the effects of PUV light on naturally present microbial load, antioxidant capacity, and antioxidant enzyme activity of fresh blueberries. Fresh blueberry samples were treated for 30, 60, 90, and 120 s. Samples were stabilized at 13 cm away from the PUV lamp before treatment. Total Aerobic Plate Count (TAPC) and yeast and mold count reduction were observed the highest in samples treated for 90 s, 1.97 and 1.27 log CFU/g, respectively. Antioxidant capacity levels were significantly different for treated samples for 60 and 90 s in FRAP analysis, whereas no differences were observed in results of DPPH analysis. Superoxide dismutase (SOD) activity as antioxidant enzyme had no difference, however, glutathione peroxidase (GPx) increased by 50% with PUV treatment for 120 s. PUV light treatment of fresh blueberries for 90 s was determined as ideal exposure time among tested time intervals of this study. PUV light illumination can generally enhance antioxidant capacity and antioxidant enzyme activity of fresh blueberries and decrease the population of natural microorganisms of fresh blueberries and similar small fruits.

Impact of Mannanase-Producing Bacillus spp. on the Accuracy of the 3M Petrifilm Aerobic Count Method

2017 ◽  
Vol 80 (7) ◽  
pp. 1117-1122
Author(s):  
Guoping Feng ◽  
Amanda Hew ◽  
Ramesh Manoharan ◽  
Siva Subramanian
Keyword(s):  
Guar Gum ◽  
Negative Impact ◽  
Gelling Agent ◽  
Plate Count ◽  
Root Cause ◽  
Bacillus Spp ◽  
Aerobic Plate Count ◽  
Relationship Of ◽  
Diffusion Assay

ABSTRACTConsistent deviations of the 3M Petrifilm aerobic counts (AC) from the standard pour plate aerobic plate count (APC) were observed with dehydrated onion and garlic products. A large study was designed to determine the relationship of these two methods and the root cause for the deviations. A total of 3,800 dehydrated onion and garlic samples were analyzed by both the Petrifilm AC and the standard pour plate APC method. Large spreader-like liquefied areas were observed on numerous Petrifilm plates. These liquefied areas made enumeration inaccurate. “Liquefier” microorganisms from Petrifilm plates were isolated and identified to species level by 16S rRNA and gyrB gene sequencing. Enzyme diffusion assay was performed to determine potential enzymatic degradation of guar gum, the gelling agent used in Petrifilm plates. The results indicated that the correlation between Petrifilm AC and standard APC is relatively low. Paired t test results suggested that the Petrifilm AC method produced significantly different results compared with standard APC. The discrepancies were attributable at least partly to a liquefier organism that hydrolyzed guar gum, leading to liquefaction. Liquefaction of Petrifilm plates seems to have two effects on accuracy: (i) liquefied areas may allow motile organisms to move and multiply in the liquefied area during the incubation period, yielding more than one colony from one cell and, as a result, leading to overestimation of the microbial load and (ii) the blurred areas obscure other colonies, leading to potential underestimation. The liquefier organism was identified as Bacillus amyloliquefaciens, a potent mannanase producer and heat-resistant spore former. Enzyme diffusion assay confirmed that mannanase contained in the cell-free supernatant of B. amyloliquefaciens can hydrolyze the 1,4-β-mannopyranosyl bond, the backbone of guar gum. This is the first report of the role of B. amyloliquefaciens in the liquefaction of Petrifilm plates and its negative impact on accuracy.

THE VALUE OF STANDARD WEATHER DATA IN YIELD–CLIMATE STUDIES OF TWO OAT VARIETIES

1966 ◽  
Vol 46 (1) ◽  
pp. 27-34 ◽  
Author(s):  
P. Dermine ◽  
H. R. Klinck
Keyword(s):  
Correlation Coefficients ◽  
Limiting Factors ◽  
Weather Data ◽  
Growth Phases ◽  
Eastern Canada ◽  
Temperature And Precipitation ◽  
Temperature Records ◽  
Precipitation Records ◽  
Relationship Of ◽  
Climate Studies

Temperature and precipitation records during various growth phases of oats were studied in relation to the yields of two varieties, Ajax and Roxton, collected at five locations in Eastern Canada, over the 1940–1956 period.Available temperature records consisted of mean maximum, mean minimum, and mean temperature range, taken in standard shelters at 4 ft above ground. Simple correlation coefficients between oat yields and the weather records were small and seldom significant. No marked improvement in correlation sensitivity was gained by separating mean daily temperature into its two components, mean maximum and minimum temperature, nor by considering weather records in relation to given growth phases of the crop. The two oat varieties belonging to opposite maturity ranges, produced correlations of similar signs with the weather data. The relative position of one variety to the other did not display any consistent or significant correlation with the weather data.On the basis of these results, standard weather records were shown to be inadequate to measure the true climate–yield relationship of a widely adapted crop such as oats, in a climate where temperature and precipitation are seldom limiting factors per se.

scholarly journals Postharvest Supply Chain with Microbial Travelers: a Farm-to-Retail Microbial Simulation and Visualization Framework

2018 ◽  
Vol 84 (17) ◽  
Author(s):  
Claire Zoellner ◽  
Mohammad Abdullah Al-Mamun ◽  
Yrjo Grohn ◽  
Peter Jackson ◽  
Randy Worobo
Keyword(s):  
Supply Chain ◽  
Foodborne Pathogens ◽  
Empirical Data ◽  
Microbial Growth ◽  
Microbial Contamination ◽  
Fresh Produce ◽  
The United States ◽  
Plate Count ◽  
Modeling Tool ◽  
Parameter Ranges

ABSTRACTFresh produce supply chains present variable and diverse conditions that are relevant to food quality and safety because they may favor microbial growth and survival following contamination. This study presents the development of a simulation and visualization framework to model microbial dynamics on fresh produce moving through postharvest supply chain processes. The postharvest supply chain with microbial travelers (PSCMT) tool provides a modular process modeling approach and graphical user interface to visualize microbial populations and evaluate practices specific to any fresh produce supply chain. The resulting modeling tool was validated with empirical data from an observed tomato supply chain from Mexico to the United States, including the packinghouse, distribution center, and supermarket locations, as an illustrative case study. Due to data limitations, a model-fitting exercise was conducted to demonstrate the calibration of model parameter ranges for microbial indicator populations, i.e., mesophilic aerobic microorganisms (quantified by aerobic plate count and here termed APC) and total coliforms (TC). Exploration and analysis of the parameter space refined appropriate parameter ranges and revealed influential parameters for supermarket indicator microorganism levels on tomatoes. Partial rank correlation coefficient analysis determined that APC levels in supermarkets were most influenced by removal due to spray water washing and microbial growth on the tomato surface at postharvest locations, while TC levels were most influenced by growth on the tomato surface at postharvest locations. Overall, this detailed mechanistic dynamic model of microbial behavior is a unique modeling tool that complements empirical data and visualizes how postharvest supply chain practices influence the fate of microbial contamination on fresh produce.IMPORTANCEPreventing the contamination of fresh produce with foodborne pathogens present in the environment during production and postharvest handling is an important food safety goal. Since studying foodborne pathogens in the environment is a complex and costly endeavor, computer simulation models can help to understand and visualize microorganism behavior resulting from supply chain activities. The postharvest supply chain with microbial travelers (PSCMT) model, presented here, provides a unique tool for postharvest supply chain simulations to evaluate microbial contamination. The tool was validated through modeling an observed tomato supply chain. Visualization of dynamic contamination levels from harvest to the supermarket and analysis of the model parameters highlighted critical points where intervention may prevent microbial levels sufficient to cause foodborne illness. The PSCMT model framework and simulation results support ongoing postharvest research and interventions to improve understanding and control of fresh produce contamination.

scholarly journals Homogeneity Test and Correction of Daily Temperature and Precipitation Data (1978–2015) in North China

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Lingling Shen ◽  
Li Lu ◽  
Tianjie Hu ◽  
Runsheng Lin ◽  
Ji Wang ◽  
...  
Keyword(s):  
Large Scale ◽  
North China ◽  
Maximum Temperature ◽  
Homogeneity Test ◽  
Climate Data ◽  
Average Temperature ◽  
Temperature And Precipitation ◽  
Daily Data ◽  
Before And After ◽  
Annual Average Temperature

Homogeneity of climate data is the basis for quantitative assessment of climate change. By using the MASH method, this work examined and corrected the homogeneity of the daily data including average, minimum, and maximum temperature and precipitation during 1978–2015 from 404/397 national meteorological stations in North China. Based on the meteorological station metadata, the results are analyzed and the differences before and after homogenization are compared. The results show that breakpoints are present pervasively in these temperature data. Most of them appeared after 2000. The stations with a host of breakpoints are mainly located in Beijing, Tianjin, and Hebei Province, where meteorological stations are densely distributed. The numbers of breakpoints in the daily precipitation series in North China during 1978–2015 also culminated in 2000. The reason for these breakpoints, called inhomogeneity, may be the large-scale replacement of meteorological instruments after 2000. After correction by the MASH method, the annual average temperature and minimum temperature decrease by 0.04°C and 0.06°C, respectively, while the maximum temperature increases by 0.01°C. The annual precipitation declines by 0.96 mm. The overall trends of temperature change before and after the correction are largely consistent, while the homogeneity of individual stations is significantly improved. Besides, due to the correction, the majority series of the precipitation are reduced and the correction amplitude is relatively large. During 1978–2015, the temperature in North China shows a rise trend, while the precipitation tends to decrease.

scholarly journals Relationship of microbial indicators to health effects at marine bathing beaches.

1979 ◽  
Vol 69 (7) ◽  
pp. 690-696 ◽  
Author(s):  
V J Cabelli ◽  
A P Dufour ◽  
M A Levin ◽  
L J McCabe ◽  
P W Haberman
Keyword(s):  
Health Effects ◽  
Microbial Indicators ◽  
Relationship Of

Study of the Microbial Ecology of Wild and Aquacultured Tunisian Fresh Fish

2011 ◽  
Vol 74 (10) ◽  
pp. 1762-1768 ◽  
Author(s):  
MOUNA BOULARES ◽  
LOBNA MEJRI ◽  
MNASSER HASSOUNA
Keyword(s):  
Aeromonas Hydrophila ◽  
Microbiological Quality ◽  
Common Species ◽  
Microbial Populations ◽  
Plate Count ◽  
Gram Negative Bacteria ◽  
Fresh Fish ◽  
Psychrotrophic Bacteria ◽  
Aerobic Plate Count

Eighty samples of fresh fish were collected in Tunisia and analyzed for microbial load. Quality and hygienic safety of the meat and intestines of wild and aquacultured fresh fish were determined. The mesophilic aerobic plate count and populations of psychrotrophic lactic acid bacteria (LAB) and other psychrotrophic bacteria ranged from 5.67 to 7.29, 4.51 to 6, and 5.07 to 6.21 log CFU/g, respectively. For all microbiological determinations, bacterial counts were lower in meat than in the intestines of fresh fish. For all samples lower microbial populations were found in most of the wild fish than in the aquacultured fish. No isolates of the pathogenic genera Salmonella and Listeria were detected in any sample. Among the 160 strains of biopreservative psychrotrophic LAB and the 150 strains of spoilage psychrotrophic gram-negative bacteria identified by biochemical and molecular methods, Lactobacillus (six species) and Pseudomonas (six species) predominated. Lactococcus, Leuconostoc, Carnobacterium (C. piscicola and C. divergens), Aeromonas, and Photobacterium were the most common genera, and Lactococcus lactis, Lactobacillus plantarum, Pseudomonas fluorescens, and Aeromonas hydrophila were the most common species. These findings indicate that the microbiological quality of fresh fish in Tunisia can be preserved by controlling pathogenic and psychrotrophic bacteria.

Microbial Quality of Hoummos (Chickpea Dip) Commercially Produced in Jordan

1994 ◽  
Vol 57 (5) ◽  
pp. 431-435 ◽  
Author(s):  
MOHAMMED I. YAMANI ◽  
BASIM A. AL-DABABSEH
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Low Ph ◽  
Plate Count ◽  
Microbial Quality ◽  
Aerobic Plate Count ◽  
And Staphylococcus Aureus ◽  
Reference Samples ◽  
Hygienic Conditions

Sixty samples of fresh hoummos (chickpea dip) from 15 restaurants were examined in winter and summer to find out numbers and types of microorganisms present. Five reference samples, produced by the investigators under hygienic conditions, were examined for comparison. The microbial load of commercial hoummos was high, and spherical lactic acid bacteria (LAB) belonging to Lactococcus, Enterococcus and Leuconostoc were the predominant microorganisms. The means of the aerobic plate count (APC) and the counts of LAB and coliforms (1.9 × 108, 1.6 × 108 and 2.9 × 105/g, respectively) in summer samples were significantly higher (p < 0.05) than the averages of the same counts in winter samples (2.7 × 107, 1.6 × 107 and 2.2 × 103/g). The average summer and winter yeast counts were 4.2 × 104 and 1.5 × 104g, respectively. In reference samples of hoummos, APC and LAB counts were < 103/g, while the coliform and yeast counts were < 10/g and 102/g, respectively, indicating lack of hygienic practices during the production of commercial hoummos. Salmonella was not detected in any sample, and Escherichia coli and Staphylococcus aureus counts of all samples were < 10/g. The relatively low pH of hoummos (the average pH of all samples was 5.1) and the rapid growth of LAB, possibly accompanied by production of inhibitory substances, may explain the predominance of these bacteria, and could have contributed to the absence of the pathogens examined.

Survey of the Bacterial Populations of Bologna Products1,2

1978 ◽  
Vol 41 (9) ◽  
pp. 692-695 ◽  
Author(s):  
JOHN T. FRUIN ◽  
JAMES F. FOSTER ◽  
JAMES L. FOWLER
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Foodborne Pathogens ◽  
High Volume ◽  
Plate Count ◽  
Retail Market ◽  
Bacterial Populations ◽  
Retail Markets ◽  
Aerobic Plate Count

Bologna products most frequently are stored and consumed as refrigerated products. Thus bacteria that survive processing or those that contaminate the product subsequent to processing are not destroyed. Ten types of presliced, vacuum-packaged bologna products were purchased from a high-volume retail market and analyzed for total aerobic plate count (APC) and common foodborne pathogens. No Salmonella were isolated. Less than 1% of the 419 samples analyzed contained either Clostridium perfringens or Escherichia coli, Staphylococcus aureus was isolated from 4% of the samples, but only one sample contained more than 1000/g. Just over 5% of the samples contained coliform organisms. The manufacturer appeared to play an important role in bacterial quality of the finished items. An APC < 5 × 106/g is a realistic criterion for bologna products at the time of delivery to retail markets.

scholarly journals Comparative study of physical, chemical, microbiological and sensory aspects of some sun dried fishes in Bangladesh

2017 ◽  
Vol 4 (8) ◽  
pp. 323-331 ◽  
Author(s):  
Bhaskar Chandra Majumdar ◽  
Faria Afrin ◽  
Md. Golam Rasul ◽  
Murshida Khan ◽  
A. K. M. Azad Shah
Keyword(s):  
Acid Value ◽  
Plate Count ◽  
Fish Products ◽  
Physical Chemical ◽  
Physico Chemical ◽  
Wallago Attu ◽  
Acceptable Quality ◽  
Dried Fish ◽  
Aerobic Plate Count ◽  
Glossogobius Giuris

An investigation was carried out to compare the physical, chemical, microbiological and sensory properties of three freshwater dried fish products of Wallago attu Bloch & Schneider, 1801 (Siluriformes: Siluridae), Channa striatus (Bloch, 1793) (Perciformes: Channidae) and Glossogobius giuris (F. Hamilton, 1822) (Perciformes: Gobiidae). The traditionally sun dried fishes were collected from Kawran Bazar Fish Market, Dhaka, Bangladesh. Results showed that the water reconstitution properties varied among the dried fishes where maximum rehydration was observed in the C. striatus at room temperature, 40 oC and 60 oC. Moisture content of W. attu, C. striatus and G. giuris were 22.70% +/- 0.45%, 18.75% +/- 0.58% and 21.93% +/- 0.54%, respectively; the protein content were 61.85% +/- 0.99%, 66.44% +/- 1.02% and 62.83% +/- 0.87%, respectively; the lipid content were 6.21% +/- 0.93%, 6.81% +/- 0.72% and 5.98% +/- 0.55%, respectively, and the ash content were 6.79% +/- 1.11%, 6.49% +/- 1.29% and 7.83% +/- 0.98%, respectively. Peroxide value, acid value, pH, TVB N value and aerobic plate count were found to be highest in W. attu followed by G. giuris and C. striatus. Results of this study revealed that traditionally sun dried fish products were acceptable quality in terms of physico-chemical, microbiological and sensory aspects.

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