Altered organoleptic properties and high total microbial count in mozarella from Italy in Germany
Archives
-
Join 8,454 other subscribers
KSWFoodWorld
Blog Stats
- 320,995 Views
Links
Category Archives: Total Viable Count
RASFF Alert- Total Microbial Count – Leg of Lamb
Spoilage and increased total microbial count in chilled leg of lamb from New Zealand in Germany
Research – Comparing the effectiveness of Cinnamomum zeylanicum essential oil and two common household sanitizers to reduce lettuce microbiota and prevent Salmonella enterica recontamination
The washing step is necessary to remove biological and physical hazards from minimally processed vegetables. Nevertheless, the risk of foodborne diseases could persist even after washing due to postsanitizing contamination, and little is known about the antimicrobial effect of residual sanitizers. This study was conducted to compare the effectiveness of sodium hypochlorite (SH), sodium bicarbonate, and Cinnamomum zeylanicum essential oil (CEO) as sanitizers on lettuce (8°C, 48 h). First, the effect of sanitizers in reducing total aerobic mesophilic and psychrotrophic bacteria, yeast and molds, lactic acid bacteria, and Enterobacteriaceae on lettuce was evaluated with some insights on lettuce quality attributes (pH, color, and sensory analysis). Then, the capability of the treatments in preventing postwashing Salmonella adhesion on lettuce surface was investigated. Commercial SH disinfectant (solution at 2%) and CEO (0.5%) reduced microbial contamination in lettuce, without affecting the overall acceptability after 48 h at 8°C. SH reduced postsanitizing Salmonella adhesion of about 2.7 Log colony forming unit (CFU)/g. The microbial reduction was confirmed by confocal laser scanning microscopy, which also evidenced Salmonella internalization within stomata. Interestingly, CEO as well reduced Salmonella adhesion but with lower efficacy (0.44–1.00 Log CFU/g reduction), while sodium bicarbonate (15 mg/ml) was not effective. In conclusion, SH and CEO seem to be effective sanitizing agents, capable of improving the microbiological profile of fresh produce. In addition, the residual sanitizers, that remain on lettuce after washing, play a role in reducing Salmonella adhesion.
Posted in Decontamination Microbial, E.coli, Enterobacteriaceae, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Mould/Mold, psychrotrophic bacteria, Research, Salmonella, Total Viable Count, Yeasts
Research – Evaluation of steam-ultrasound decontamination on naturally contaminated broilers through the analysis of Campylobacter, total viable count, and Enterobacteriaceae
Combined steam-ultrasound process was investigated for decontamination of freshly slaughtered broilers. Combined steam-ultrasound was delivered simultaneously through specially designed nozzles. The nozzles were installed inside of a constructed machine that allowed for continuous processing. The aim of this study was to evaluate the decontamination effect of the steam- ultrasound application with a capacity of 10,500 birds/hour on naturally contaminated broilers, using three different skin sampling areas for microbial analysis (back, breast and the neck skin). Microbial analysis of Campylobacter , Enterobacteriaceae and Total Viable Count (TVC), was performed pre- and -post steam-ultrasound treatment. A total of 648 skin samples were analyzed for Campylobacter and a total of 216 samples were analyzed for Enterobacteriaceae and TVC. R esults showed significant (p<0.001) Campylobacter reductions of 0.8 log, 1.1 log and 0.7 log, analyzed from skin samples taken from the back, breast and the neck, respectively. Significant reductions of Enterobacteriaceae (p<0.001) by 1.6 log, 1.9 log and 1.1 log and significant reductions of TVC (p<0.001) by 2.0 log, 2.4 log and 1.3 log were found on back, breasts and neck, respectively. Refrigeration effect on Campylobacter numbers pre- and post- steam-ultrasound treatment and incubation at 4°C for eight days was determined in a small trial with 12 samples. Results showed significant (p<0.01) reductions of 0.9 log analyzed on breast skin samples, and 0.7 log reduction (p<0.05) on neck skin samples. Results in this study showed that significant bacteria reduction was achieved on three different surface areas on broilers at a slaughter-speed of 10,500b/h with temperatures over 80°C. The rapid treatment of less than 1.5s exposure time per bird chamber, makes this technology potentially suitable for modern and fast poultry processing lines.
Posted in Campylobacter, Campylobacter jejuni, Enterobacteriaceae, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Technology, Total Viable Count
Research – Determining bacterial load and water quality of tomato flume tanks in Florida packinghouses
Monitoring and maintenance of water quality in dump tanks or flume systems is crucial to prevent pathogen cross-contamination during postharvest washing of tomatoes, but there is limited information on how organic matter influences sanitizer efficacy in the water. The main objective of this study was to monitor water quality in flume tanks and evaluate the efficacy of postharvest washing of tomatoes in commercial packinghouses. Flume tank water samples (n=3) were collected on an hourly basis from three packinghouses in Florida and analyzed for pH, total dissolved solids (TDS), free chlorine, chemical oxygen demand (COD), oxidation-reduction potential (ORP), and turbidity. Additionally, three flume water samples were collected and tested for total aerobic plate count (APC), total coliforms (TC), and generic E. coli (EC). Fresh tomatoes (n=3), both before and after washing, were collected and analyzed for the same bacterial counts. Turbidity, COD, and TDS levels in flume water increased over time in all packinghouses. Correlations observed include COD and turbidity (r = 0.631), turbidity and TDS (r = 0.810), and ORP and chlorine (r = 0.660). APC for water samples had an average range of 0.0 to 4.7 log CFU/mL and TC average range of 0.0 to 4.7 log CFU/mL. All water samples were negative for generic E. coli . The average APC for pre-and post-flume tomatoes from the three packinghouses was 6.0 log CFU/tomato and ranged from 2.2 to 7.4 log CFU/tomato. The average TC count was <1.5 and 7.0 log CFU/tomato for pre-and post-wash tomatoes, respectively. There was no significant effect ( P >0.05) of postharvest washing on the microbiological qualities of tomatoes. Water quality in flume tanks deteriorated over time in all packinghouses during a typical operational day of 4-8 h.
Research – Microbiological Survey of Wheat Flour Sold at Retail in Canada, 2018-2019
Following two O121 STEC outbreaks linked to wheat flour, this study was conducted to gain baseline information on the occurrence of bacterial pathogens and levels of indicator organisms in wheat flour in Canada. A total of 347 pre-packaged wheat flour samples were analyzed for Salmonella spp., Shiga Toxin-Producing Escherichia coli (STEC), Listeria monocytogenes ( L. monocytogenes ) , aerobic colony count (ACC), total coliforms, and generic Escherichia coli ( E. coli ) . Salmonella spp. and O157 STEC were not detected in any of the samples. L. monocytogenes was identified in two samples (0.6%) at levels below the limit of detection (<0.7 log CFU/g). Non-O157 STEC were isolated from six samples (1.7%) and were characterized for the presence of STEC virulence genes: stx 1, stx 2 and subtypes, eae , hlyA, and aggR . One O103:H25 STEC isolate carried virulence genes ( stx 1 a + eae ) that are known to be capable of causing diarrhea and/or bloody diarrhea in humans. Of the five remaining non-O157 STEC isolates, four carried single stx 2a or stx 2c genes and were considered to have the potential of causing diarrhea. The remaining non-O157 STEC isolate ( stx 2 ), while not a priority non-O157 STEC was not available for sequencing and thus its potential to cause illness is unknown. ACC, total coliforms, and generic E. coli were detected in 98.8%, 72.6% and 0.6% of the flour samples. The mean counts of ACC were greater in whole-wheat flour as compared to the other flour types tested ( p <0.001). The results of this study suggest that the occurrence of O157 STEC and Salmonella is low, but the occurrence of non-O157 STEC in wheat flour with the potential to cause human illness of diarrhea is relatively common. Therefore, the consumption of raw flour could increase the likelihood of STEC infections. Further research is merited for potential risk mitigation strategies within the food production system and with consumers.
Research – Does physical state of farm housing and milking practices affect total bacteria and somatic cell count of cow milk?
Abstract
The study determined the effect of physical state of farm housing on total bacteria and somatic cell count (SCC) of cow milk. Milk records collected at Dairy Services Zimbabwe were used. Effects of physical state of ceilings, doors, ventilation, walls, drains, fly‐proofs, windows and roof type on total bacterial count (TBC) in milk, and SCC were determined using general linear models procedure. Poor physical state of ceilings, doors and floors in milking parlors, wash rooms and bulk tank rooms result in high TBC and SCC in milk (p < 0.05). Poor ventilation in the bulk tank room results in high TBC in milk (p < 0.05). Floors, doors, and ceilings of milking houses should be kept in sound condition and good repair in order minimize TBC and SCC in raw milk.
Practical applications
Understanding how physical state of farm houses and management practices affect total bacterial count and somatic cell count in fresh milk enables farmers and regulatory agencies to put in corrective action to reduce bacterial contamination of milk at farm level. This helps keep the population of disease causing bacteria in raw milk, which is widely consumed by human beings, as low as possible. It also helps reduce contamination by some resistant bacteria that might survive processing and cause further defects in milk products. The shelf‐life of the milk and its products is, thus, improved. Reducing bacterial and somatic cell count in raw milk also helps the milk producers to score high milk grades on the market and, thus, fetch high prices.
Research – Microbial quality of edible grasshoppers Ruspolia differens (Orthoptera: Tettigoniidae): From wild harvesting to fork in the Kagera Region, Tanzania
Abstract
In Tanzania, edible Ruspolia differens are still harvested from the natural environments. In this perspective, little is known about the microbiological quality of wild harvested R. differens. This study was conducted to assess the microbiological quality of wild harvested R. differens and evaluate the efficacy of conventional processing methods in reducing microbial load. Two districts (Bukoba rural and Muleba) within the Kagera region were purposively selected for the study. Sampling was done from the same batches along the R. differens food chain as follows: (a) at harvest points in the villages, (b) after transportation to the market and plucking of wings and legs, (c) after rinsing with potable tap water, and (d) after processing using conventional methods. Generally, high microbial counts, that is, total viable aerobic count (TVC), Enterobacteriaceae, lactic acid bacteria, bacterial endospores, and yeasts and molds were observed in raw R. differenssamples. A significant increase in microbial counts after transportation and plucking was only observed for TVC, bacterial endospores, and yeasts and molds. A statistically significant reduction in all types of counts, with the exception of bacterial endospores, was observed after processing. All processed samples analyzed were devoid of salmonellae, Listeria monocytogenes, and Escherichia coli.
Practical applications
Although commonly used processing methods of Ruspolia differens were effective in reducing microbial load, bacterial endospores were hardly eliminated and could pose a health hazard to consumers; thus, improved handling of R. differens along the food chain could reduce such risks.
Research – Survival of food‐borne bacterial pathogens in traditional Mediterranean anchovy products
Abstract
The aim of this study was to investigate the survival of Salmonella Enteritidis, Staphylococcus aureus and Listeria monocytogenes in salted and marinated anchovy (Engraulis encrasicholus). Total viable counts (TVCs), lactic acid bacteria, Enterobacteriaceae, and yeasts/molds were also enumerated. Initially, TVC was as high as 5.5 log10 cfu/g, but the population dropped down to 3.2 and 2.2 log10 CFU/g for salted and marinated anchovy, respectively. S. aureus was the most salt‐tolerant and L. monocytogenes was the most acid‐tolerant microorganism. A biphasic inactivation of S. Enteriditis and L. monocytogenes was apparent during the 8‐hr marination process, implying adaptation and resistance to low pH. Results suggest that salting or marinating of anchovy creates an environment in which pathogenic bacteria are inactivated. However, inherent resistance or possible adaptation to stresses can result to prolonged inactivation times; hence it is important to avoid contamination with high numbers of food‐borne pathogens.
Practical applications
Many food‐borne bacterial pathogens can survive at low pH and aw, especially in cases in which they might adapt to the imposed stresses and become resistant. Knowing the time required to reduce food‐borne pathogens is of great interest for ensuring safety of traditional seafood.
Posted in Enterobacteriaceae, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Testing, lactic acid bacteria, Listeria, Listeria monocytogenes, Moulds, Salmonella, Staphylococcus aureus, Total Viable Count, Uncategorized, Yeasts
HPA Scotland – Contaminated Water Tanks
A recent Estates and Facilities Alert issued by Health Facilities Scotland (HFS) has noted that contamination of water supplies was found in two recent projects within NHS Scotland. Extensive testing traced the source to the cold water storage tanks which gave TVC (Total Viable Count) readings for Pseudomonas in excess of 500cfu/100ml (after 72-hour incubation). TVC readings fell to 0cfu/100ml immediately after disinfecting the tanks but had reverted to high levels at later re-testing.
Posted in Bacteria, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Safety, Food Testing, Health Protection England, Hygiene, Laboratory, Microbiology, Pseudomonas, Research, Total Viable Count, Water
Tagged Health Facilities Scotland, Health Protection Scotland, NHS Scotland
FoodWorld 