Bismarck Martinez - Academia.edu (original) (raw)

Papers by Bismarck Martinez

Escherichia coli O157:H7 is a human pathogen that can cause a wide spectrum of disease symptoms, ... more Escherichia coli O157:H7 is a human pathogen that can cause a wide spectrum of disease symptoms, such as bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Escherichia coli O157:H7 illness are mainly associated with undercooked beef; however, in recent years outbreaks have been linked to fresh produce such as spinach, lettuce, and sprouts. In 2009, flour was implicated as a contamination source in the consumption of raw cookie dough resulting in 77 illness-cases. The objective of this research was to determine the possible route of transmission of E. coli O157:H7 into the phyllo-plane of wheat using contaminated seed, soil or irrigation water. Levels of contamination were 6.88 log CFU/g, 6.60 log CFU/g and 6.76 log CFU/ml of Kanamycin resistant E. coli O157:H7. One hundred plants per treatment were sown in pots trays with 50 g of sterile soil, watered every day with 5 ml of dilution water and harvested after 9 days post-inoculation. In a fourth experiment, fl...

Sustainable Water and Wastewater Processing, 2019

Abstract The food industry faces the challenges of scarce water resources for processing and sign... more Abstract The food industry faces the challenges of scarce water resources for processing and significant volumes of nutrient-rich wastewater resulting from its operations. Recondition and reuse of water are effective options to improve water availability while reducing environmental impacts due to the discharge of untreated wastewater. Different food sectors offer unique conditions to design and implement water reconditioning and reuse alternatives. However, there are several fundamental concepts, discussed herein, that guide the decision-making process, those include technologies, regulations, considerations regarding food safety, risk perceptions, water quality, environmental impacts, and gaps of knowledge. This chapter discusses feasible water conservation strategies while highlighting current limitations and opportunities to process food with less water.

Journal of Food Protection, 2021

Food manufacturers often use squeegees as a tool to remove condensation from overhead surfaces. T... more Food manufacturers often use squeegees as a tool to remove condensation from overhead surfaces. This practice is done to reduce the likelihood of environmental pathogen contamination by eliminating condensed-water droplets that could fall from overhead surfaces during production. However, this practice may actually spread environmental pathogens across these surfaces, defeating its purpose and further increasing the risk for contamination in the processing area. To understand the risk associated with this common practice, test pipes inoculated with Listeria innocua ATCC 33090 were exposed to steam to produce condensation, which was then removed by squeegees. The pipe surfaces, droplets, and squeegees were subsequently analyzed for Listeria to determine the distance the organism spread across the pipe and how many organisms were transferred to the droplets and the squeegees. Results showed that Listeria traveled as far as 16 in. across the surface of the pipe, and bacterial transfer ...

Dairy processing facilities need to control spoilage microorganisms in fluid milk in order to rea... more Dairy processing facilities need to control spoilage microorganisms in fluid milk in order to reach markets and increase their profits. The major contributors for early spoilage on fluid milk are sporeforming bacteria capable of growing under refrigeration temperature and Post- Pasteurization Contamination (PPC) organism. Since these two groups of organisms have different survival characteristics, strategies to control them may require different approaches. Therefore, identification of bacteria contributing to spoilage becomes essential. The objective of this research was to identify the spoilage bacteria, mainly sporeformers, associated with laboratory heat-treated milk (80°C for 12 min) and commercially-pasteurized fluid milk, throughout a production chain in Nebraska. Identification was done using the rpoB gene and/or partial 16S rDNA sequences. Raw and pasteurized milk samples were collected from different locations (farm, trucks, processing plant, and packaged products) during ...

Food Control, 2018

Approximately one-third of the fluid milk produced in the United States is lost annually. One imp... more Approximately one-third of the fluid milk produced in the United States is lost annually. One important factor contributing to the loss is the contamination with spore-forming bacteria, which can not only survive the pasteurization process but also grow under refrigeration conditions, resulting in subsequent spoilage. The objective of this study was to describe the population dynamics of spore-forming bacteria in milk, from the farm to the packaged product, through a systematic review approach. A database search was conducted to identify, appraise, and summarize primary research studies that described the prevalence and/or concentration of spore-forming bacteria throughout the fluid milk supply chain. Due to variations in sampling points in reported studies, the pasteurized milk supply chain was standardized to include the following steps: "milking machine", "raw milk", "bulk tank", "transportation", "silo", "pasteurized milk" and "packaged milk". A literature search retrieved 9,778 citations, from which 46 relevant citations were selected for data extraction and subsequent meta-analysis. Concentration data were more abundant with 758 data points, as compared to prevalence data with 74 data points. In general, great heterogeneity was observed among studies on the contamination in milk samples with spore-forming bacteria. The findings showed that the concentration of spore-forming bacteria in milk samples increased within the range of 0.58e2.41 logs CFU/mL from raw milk to pasteurized milk according to the weighted mean estimates. Similarly, the prevalence of contaminated samples with sporeforming bacteria increased from 23% on farm, to up to 58% at the step of "pasteurized milk". Metaregression analysis indicates that the variables, season and location, of the study, accounted for 56.35% of the between-study heterogeneity. Although considerable primary research has been conducted on this topic, there are limited studies that comprehensively describe the dynamic changes of spore-forming bacteria under the current milk production system. In summary, the analyses based on comprehensively collected evidence show that the contamination of spore-forming bacteria originating from the farm remains stable with steady increases as the milk moves downstream. These findings indicate that in addition to on-farm interventions, special attention should be paid to introducing effective mitigation measures at the processing stage to further lower spore-forming bacteria levels introduced by the raw milk, and to prevent post-pasteurization contamination from raw ingredients and processing environments.

Journal of dairy science, 2017

Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in ... more Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in milk after pasteurization. They have been reported to affect the quality of dairy products by the production of enzymes (lipolytic and proteolytic) under low-temperature conditions in fluid milk, and have become a limiting factor for milk powder in reaching some selective markets. The objective of this research was to isolate and identify the population of spore-forming bacteria (psychrotrophic and thermophilic strains) associated with concentrated milk processing in Nebraska. During 2 seasons, in-process milk samples from a commercial plant (raw, pasteurized, and concentrated) were collected and heat-treated (80°C/12 min) to recover only spore-formers. Samples were spread-plated using standard methods agar and incubated at 32°C to enumerate mesophilic spore counts. Heat-treated samples were also stored at 7°C and 55°C to recover spore-formers that had the ability to grow under those tem...

Journal of Food Protection, 2012

Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highligh... more Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highlight the need for the food and feed industries to validate their extrusion processes to ensure the destruction of pathogenic microorganisms. Response surface methodology was employed to study the effect of moisture and temperature on inactivation by extrusion of Enterococcus faecium NRRL B-2354 in a carbohydrate-protein mix. A balanced carbohydrate-protein mix was formulated to different combinations of moisture contents, ranging from 24.9 to 31.1%, and each was inoculated with a pure culture of E. faecium to a final level of 5 log CFU/g. Each mix of various moistures was then extruded in a pilot scale extruder at different temperatures (ranging from 67.5 to 85°C). After the extruder was allowed to equilibrate for 10 min, samples were collected in sterile bags, cooled in dry ice, and stored at 4°C prior to analysis. E. faecium was enumerated with tryptic soy agar and membrane Enterococcus m...

Journal of Food Protection, 2014

Multiple outbreaks of salmonellosis have been associated with the consumption of low-moisture pro... more Multiple outbreaks of salmonellosis have been associated with the consumption of low-moisture products, including extruded products. Therefore, there is a need for a nonpathogenic, surrogate microorganism that can be used to validate extrusion processes for Salmonella. The objective of this research was to determine if Enterococcus faecium NRRL B-2354 is an adequate surrogate organism for Salmonella during extrusion. Extrusions at different temperatures were done in material contaminated with both organisms. Results indicated that the minimum temperature needed to achieve a 5-log reduction of E. faecium was 73.7°C. Above 80.3°C, the enumeration of E. faecium showed counts below the detectable levels (<10 CFU g−1). Salmonella was reduced by 5 log at 60.6°C, and above 68.0°C the levels of this organism in the product were below the detection limit of the method. The data show that E. faecium is inactivated at higher temperatures than Salmonella, indicating that its use as a surroga...

Journal of food protection, 2015

Escherichia coli O157:H7 is a human pathogen that can cause bloody diarrhea, hemorrhagic colitis,... more Escherichia coli O157:H7 is a human pathogen that can cause bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. E. coli O157:H7 illnesses are mainly associated with undercooked beef; however, in recent years, outbreaks have been linked to fresh produce, such as spinach, lettuce, and sprouts. In 2009, flour was implicated as the contamination source in an outbreak involving consumption of raw cookie dough that resulted in 77 illnesses. The objectives of this research were to determine (i) whether E. coli O157:H7 could be translocated into the internal tissues of wheat (Triticum aestivum) seedlings from contaminated seed, soil, or irrigation water and (ii) whether the bacterium could survive on flowering wheat heads. The levels of contamination of kanamycin-resistant E. coli O157:H7 strains in seed, soil, and irrigation water were 6.88 log CFU/g, 6.60 log CFU/g, and 6.76 log CFU/ml, respectively. One hundred plants per treatment were sown in pot trays with 50 g of aut...

Journal of Food Protection, 2012

Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highligh... more Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highlight the need for the food and feed industries to validate their extrusion processes to ensure the destruction of pathogenic microorganisms. Response surface methodology was employed to study the effect of moisture and temperature on inactivation by extrusion of Enterococcus faecium NRRL B-2354 in a carbohydrate-protein mix. A balanced carbohydrate-protein mix was formulated to different combinations of moisture contents, ranging from 24.9 to 31.1%, and each was inoculated with a pure culture of E. faecium to a final level of 5 log CFU/g. Each mix of various moistures was then extruded in a pilot scale extruder at different temperatures (ranging from 67.5 to 85°C). After the extruder was allowed to equilibrate for 10 min, samples were collected in sterile bags, cooled in dry ice, and stored at 4°C prior to analysis. E. faecium was enumerated with tryptic soy agar and membrane Enterococcus media, followed by incubation at 35°C for 48 h. Each extrusion was repeated twice, with the central point of the design being repeated four times. From each extrusion, three subsamples were collected for microbial counts and moisture determination. Based on the results, the response surface model was y = 185.04 - 3.11X(1) - 4.23X(2) + 0.02X(1)(2) - 0.004X(1)X(2) + 0.08X(2)(2), with a good fit (R(2) = 0.92), which demonstrated the effects of moisture and temperature on the inactivation of E. faecium during extrusion. According to the response surface analysis, the greatest reduction of E. faecium for the inoculation levels studied here (about 5 log) in a carbohydrate-protein meal would occur at the temperature of 81.1°C and moisture content of 28.1%. Other temperature and moisture combinations needed to achieve specific log reductions were plotted in a three-dimensional response surface graph.

Escherichia coli O157:H7 is a human pathogen that can cause a wide spectrum of disease symptoms, ... more Escherichia coli O157:H7 is a human pathogen that can cause a wide spectrum of disease symptoms, such as bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Escherichia coli O157:H7 illness are mainly associated with undercooked beef; however, in recent years outbreaks have been linked to fresh produce such as spinach, lettuce, and sprouts. In 2009, flour was implicated as a contamination source in the consumption of raw cookie dough resulting in 77 illness-cases. The objective of this research was to determine the possible route of transmission of E. coli O157:H7 into the phyllo-plane of wheat using contaminated seed, soil or irrigation water. Levels of contamination were 6.88 log CFU/g, 6.60 log CFU/g and 6.76 log CFU/ml of Kanamycin resistant E. coli O157:H7. One hundred plants per treatment were sown in pots trays with 50 g of sterile soil, watered every day with 5 ml of dilution water and harvested after 9 days post-inoculation. In a fourth experiment, fl...

Sustainable Water and Wastewater Processing, 2019

Abstract The food industry faces the challenges of scarce water resources for processing and sign... more Abstract The food industry faces the challenges of scarce water resources for processing and significant volumes of nutrient-rich wastewater resulting from its operations. Recondition and reuse of water are effective options to improve water availability while reducing environmental impacts due to the discharge of untreated wastewater. Different food sectors offer unique conditions to design and implement water reconditioning and reuse alternatives. However, there are several fundamental concepts, discussed herein, that guide the decision-making process, those include technologies, regulations, considerations regarding food safety, risk perceptions, water quality, environmental impacts, and gaps of knowledge. This chapter discusses feasible water conservation strategies while highlighting current limitations and opportunities to process food with less water.

Journal of Food Protection, 2021

Food manufacturers often use squeegees as a tool to remove condensation from overhead surfaces. T... more Food manufacturers often use squeegees as a tool to remove condensation from overhead surfaces. This practice is done to reduce the likelihood of environmental pathogen contamination by eliminating condensed-water droplets that could fall from overhead surfaces during production. However, this practice may actually spread environmental pathogens across these surfaces, defeating its purpose and further increasing the risk for contamination in the processing area. To understand the risk associated with this common practice, test pipes inoculated with Listeria innocua ATCC 33090 were exposed to steam to produce condensation, which was then removed by squeegees. The pipe surfaces, droplets, and squeegees were subsequently analyzed for Listeria to determine the distance the organism spread across the pipe and how many organisms were transferred to the droplets and the squeegees. Results showed that Listeria traveled as far as 16 in. across the surface of the pipe, and bacterial transfer ...

Dairy processing facilities need to control spoilage microorganisms in fluid milk in order to rea... more Dairy processing facilities need to control spoilage microorganisms in fluid milk in order to reach markets and increase their profits. The major contributors for early spoilage on fluid milk are sporeforming bacteria capable of growing under refrigeration temperature and Post- Pasteurization Contamination (PPC) organism. Since these two groups of organisms have different survival characteristics, strategies to control them may require different approaches. Therefore, identification of bacteria contributing to spoilage becomes essential. The objective of this research was to identify the spoilage bacteria, mainly sporeformers, associated with laboratory heat-treated milk (80°C for 12 min) and commercially-pasteurized fluid milk, throughout a production chain in Nebraska. Identification was done using the rpoB gene and/or partial 16S rDNA sequences. Raw and pasteurized milk samples were collected from different locations (farm, trucks, processing plant, and packaged products) during ...

Food Control, 2018

Approximately one-third of the fluid milk produced in the United States is lost annually. One imp... more Approximately one-third of the fluid milk produced in the United States is lost annually. One important factor contributing to the loss is the contamination with spore-forming bacteria, which can not only survive the pasteurization process but also grow under refrigeration conditions, resulting in subsequent spoilage. The objective of this study was to describe the population dynamics of spore-forming bacteria in milk, from the farm to the packaged product, through a systematic review approach. A database search was conducted to identify, appraise, and summarize primary research studies that described the prevalence and/or concentration of spore-forming bacteria throughout the fluid milk supply chain. Due to variations in sampling points in reported studies, the pasteurized milk supply chain was standardized to include the following steps: "milking machine", "raw milk", "bulk tank", "transportation", "silo", "pasteurized milk" and "packaged milk". A literature search retrieved 9,778 citations, from which 46 relevant citations were selected for data extraction and subsequent meta-analysis. Concentration data were more abundant with 758 data points, as compared to prevalence data with 74 data points. In general, great heterogeneity was observed among studies on the contamination in milk samples with spore-forming bacteria. The findings showed that the concentration of spore-forming bacteria in milk samples increased within the range of 0.58e2.41 logs CFU/mL from raw milk to pasteurized milk according to the weighted mean estimates. Similarly, the prevalence of contaminated samples with sporeforming bacteria increased from 23% on farm, to up to 58% at the step of "pasteurized milk". Metaregression analysis indicates that the variables, season and location, of the study, accounted for 56.35% of the between-study heterogeneity. Although considerable primary research has been conducted on this topic, there are limited studies that comprehensively describe the dynamic changes of spore-forming bacteria under the current milk production system. In summary, the analyses based on comprehensively collected evidence show that the contamination of spore-forming bacteria originating from the farm remains stable with steady increases as the milk moves downstream. These findings indicate that in addition to on-farm interventions, special attention should be paid to introducing effective mitigation measures at the processing stage to further lower spore-forming bacteria levels introduced by the raw milk, and to prevent post-pasteurization contamination from raw ingredients and processing environments.

Journal of dairy science, 2017

Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in ... more Spore-forming bacteria are heat-resistant microorganisms capable of surviving and germinating in milk after pasteurization. They have been reported to affect the quality of dairy products by the production of enzymes (lipolytic and proteolytic) under low-temperature conditions in fluid milk, and have become a limiting factor for milk powder in reaching some selective markets. The objective of this research was to isolate and identify the population of spore-forming bacteria (psychrotrophic and thermophilic strains) associated with concentrated milk processing in Nebraska. During 2 seasons, in-process milk samples from a commercial plant (raw, pasteurized, and concentrated) were collected and heat-treated (80°C/12 min) to recover only spore-formers. Samples were spread-plated using standard methods agar and incubated at 32°C to enumerate mesophilic spore counts. Heat-treated samples were also stored at 7°C and 55°C to recover spore-formers that had the ability to grow under those tem...

Journal of Food Protection, 2012

Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highligh... more Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highlight the need for the food and feed industries to validate their extrusion processes to ensure the destruction of pathogenic microorganisms. Response surface methodology was employed to study the effect of moisture and temperature on inactivation by extrusion of Enterococcus faecium NRRL B-2354 in a carbohydrate-protein mix. A balanced carbohydrate-protein mix was formulated to different combinations of moisture contents, ranging from 24.9 to 31.1%, and each was inoculated with a pure culture of E. faecium to a final level of 5 log CFU/g. Each mix of various moistures was then extruded in a pilot scale extruder at different temperatures (ranging from 67.5 to 85°C). After the extruder was allowed to equilibrate for 10 min, samples were collected in sterile bags, cooled in dry ice, and stored at 4°C prior to analysis. E. faecium was enumerated with tryptic soy agar and membrane Enterococcus m...

Journal of Food Protection, 2014

Multiple outbreaks of salmonellosis have been associated with the consumption of low-moisture pro... more Multiple outbreaks of salmonellosis have been associated with the consumption of low-moisture products, including extruded products. Therefore, there is a need for a nonpathogenic, surrogate microorganism that can be used to validate extrusion processes for Salmonella. The objective of this research was to determine if Enterococcus faecium NRRL B-2354 is an adequate surrogate organism for Salmonella during extrusion. Extrusions at different temperatures were done in material contaminated with both organisms. Results indicated that the minimum temperature needed to achieve a 5-log reduction of E. faecium was 73.7°C. Above 80.3°C, the enumeration of E. faecium showed counts below the detectable levels (<10 CFU g−1). Salmonella was reduced by 5 log at 60.6°C, and above 68.0°C the levels of this organism in the product were below the detection limit of the method. The data show that E. faecium is inactivated at higher temperatures than Salmonella, indicating that its use as a surroga...

Journal of food protection, 2015

Escherichia coli O157:H7 is a human pathogen that can cause bloody diarrhea, hemorrhagic colitis,... more Escherichia coli O157:H7 is a human pathogen that can cause bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. E. coli O157:H7 illnesses are mainly associated with undercooked beef; however, in recent years, outbreaks have been linked to fresh produce, such as spinach, lettuce, and sprouts. In 2009, flour was implicated as the contamination source in an outbreak involving consumption of raw cookie dough that resulted in 77 illnesses. The objectives of this research were to determine (i) whether E. coli O157:H7 could be translocated into the internal tissues of wheat (Triticum aestivum) seedlings from contaminated seed, soil, or irrigation water and (ii) whether the bacterium could survive on flowering wheat heads. The levels of contamination of kanamycin-resistant E. coli O157:H7 strains in seed, soil, and irrigation water were 6.88 log CFU/g, 6.60 log CFU/g, and 6.76 log CFU/ml, respectively. One hundred plants per treatment were sown in pot trays with 50 g of aut...

Journal of Food Protection, 2012

Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highligh... more Outbreaks of salmonellosis and recalls of low-moisture foods including extruded products highlight the need for the food and feed industries to validate their extrusion processes to ensure the destruction of pathogenic microorganisms. Response surface methodology was employed to study the effect of moisture and temperature on inactivation by extrusion of Enterococcus faecium NRRL B-2354 in a carbohydrate-protein mix. A balanced carbohydrate-protein mix was formulated to different combinations of moisture contents, ranging from 24.9 to 31.1%, and each was inoculated with a pure culture of E. faecium to a final level of 5 log CFU/g. Each mix of various moistures was then extruded in a pilot scale extruder at different temperatures (ranging from 67.5 to 85°C). After the extruder was allowed to equilibrate for 10 min, samples were collected in sterile bags, cooled in dry ice, and stored at 4°C prior to analysis. E. faecium was enumerated with tryptic soy agar and membrane Enterococcus media, followed by incubation at 35°C for 48 h. Each extrusion was repeated twice, with the central point of the design being repeated four times. From each extrusion, three subsamples were collected for microbial counts and moisture determination. Based on the results, the response surface model was y = 185.04 - 3.11X(1) - 4.23X(2) + 0.02X(1)(2) - 0.004X(1)X(2) + 0.08X(2)(2), with a good fit (R(2) = 0.92), which demonstrated the effects of moisture and temperature on the inactivation of E. faecium during extrusion. According to the response surface analysis, the greatest reduction of E. faecium for the inoculation levels studied here (about 5 log) in a carbohydrate-protein meal would occur at the temperature of 81.1°C and moisture content of 28.1%. Other temperature and moisture combinations needed to achieve specific log reductions were plotted in a three-dimensional response surface graph.