The Experts below are selected from a list of 25938 Experts worldwide ranked by ideXlab platform
Dennis J Damico - One of the best experts on this subject based on the ideXlab platform.
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compatibility of commercially produced protective cultures with common cheesemaking cultures and their antagonistic effect on foodborne pathogens
Journal of Food Protection, 2020Co-Authors: Stephanie R B Brown, Catherine Gensler, Sulaiman F Aljasir, Dennis J DamicoAbstract:ABSTRACT The documented survival of pathogenic bacteria, including Listeria monocytogenes (LM), Shiga toxin-producing Escherichia coli (STEC), and Salmonella during the manufacture and aging of some cheeses highlights the need for additional interventions to enhance food safety. Unfortunately, few interventions are compliant with the Standards of Identity for cheese. Protective bacterial cultures (PCs) represent actionable, natural interventions. However, supportive data for commercially produced PCs regarding their efficacy against pathogens and potential antagonism with each other and cheesemaking cultures are scant, thereby impeding their potential use by the cheese industry. The overall objective of this study was to identify commercially produced PCs that exert antimicrobial activity toward pathogens with minimal impact on beneficial cheese microbes. Direct antagonism and agar well diffusion assays were used to determine the impact of 10 commercially produced PCs on the growth of starter cultures and cultures of ripening bacteria and fungi. Deferred antagonism was used to evaluate the potential for antimicrobial effects against LM, STEC, and Salmonella. PCs and starter cultures were cocultured in ultrahigh-temperature-processed milk to determine the effects of coculture on starter acidification profiles when incubated according to a simulated cheesemaking temperature profile (4 h at 35°C followed by 20 h at 20°C). Compatibility assays suggest that PC antagonism is microbe and strain specific. Only one PC negatively impacted the acidification of the starters tested. PC antagonism of ripening bacteria and fungi growth varied but was consistent within species. All PCs displayed deferred inhibition of LM, STEC, and Salmonella growth, but to varying degrees. These data identify commercial PCs with potential for the control of pathogens and characterize their compatibility with cheesemaking cultures for future use by cheesemakers and investigations of their efficacy in the production of cheese. HIGHLIGHTS
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incidence ecology and fate of target foodborne pathogens in the cheesemaking continuum
2008Co-Authors: Dennis J DamicoAbstract:Due to renewed interest in specialty cheeses, small-scale artisan and farmstead producers are manufacturing numerous varieties of cheese, including those that present higher risk such as surface-ripened soft cheeses, often using raw milk. The presence of pathogenic bacteria in raw milk on large scale dairy farms is well documented as the dairy farm itself can serve as a reservoir. To assess the risks associated with the use of raw milk in the manufacture of small-scale artisan cheese we evaluated overall milk quality and prevalence of four target pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., and Escherichia coli O157:H7) in raw milk from 11 farmstead cheese operations in Vermont. Although overall incidence was low in comparison to other surveys, variation from farm to farm, independent of species, indicates that some operations practice strict hygienic controls and that additional effort is needed on others. Our data also suggest that if present, pathogen population levels in raw milk are extremely low. Although these pathogens are readily inactivated by pasteurization, pasteurized milk and milk products, including soft cheese, have been implicated in major outbreaks of L. monocytogenes infection as the result of post-processing environmental contamination. U.S. Standards of Identity permit the manufacture of these and other cheeses from raw milk, provided they are aged for a minimum of 60 days typically at a temperature no less than 35°F (1.67°C) to provide safety. of particular concern are the surface-mold-ripened soft cheeses due to the growth potential during aging and refrigerated holding following increases in pH. In a study on the growth potential of L. monocytogenes introduced as post process contaminants on surface-mold-ripened cheeses we demonstrate that holding cheese in compliance with U.S. Federal regulations supports pathogen growth from very low levels regardless of the whether the milk used was raw or pasteurized. Moreover, the 60 day aging rule encourages extended holding which could inadvertently contribute to risk. It is clear that the safety of cheeses within this category must be achieved through control strategies other than pasteurization or aging. Effective environmental monitoring and control of Listeria spp. within processing plants, including farmstead cheese operations, is considered paramount in reducing cross contamination of ready-to-eat foods. To assess the incidence and ecology of Listeria spp. in farmstead cheese processing environments we conducted environmental sampling in 9 different cheesemaking facilities over a 10-week period while comparing three detection/isolation protocols. Results indicate that the use of detection/isolation methods incorporating dual primary enrichment with a repair step allowing for the recovery of injured Listeria enhances detection of Listeria spp., including L. monocytogenes, and that the addition of PCR increases sensitivity of detection while greatly reducing time to results. Our data indicate that the extent of farmstead cheese plant contamination with Listeria spp., notably L. monocytogenes, is comparatively low for dairy processing plants, especially those with contiguous farms and aids in the identification of control points for use in designing more effective control and monitoring programs. Overall the studies contained herein fill data gaps in the literature considering the threat of emerging pathogens in raw milk intended for farmstead cheesemaking, as well as the incidence and distribution of Listeria spp., including molecular subtypes, in small farmstead cheese processing environments over time. These data will help inform risk assessments which evaluate the microbiological safety of artisan cheeses, particularly those manufactured on farms.
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60 day aging requirement does not ensure safety of surface mold ripened soft cheeses manufactured from raw or pasteurized milk when listeria monocytogenes is introduced as a postprocessing contaminant
Journal of Food Protection, 2008Co-Authors: Dennis J Damico, Marc J Druart, Catherine W DonnellyAbstract:Because of renewed interest in specialty cheeses, artisan and farmstead producers are manufacturing surface-mold-ripened soft cheeses from raw milk, using the 60-day holding standard (21 CFR 133.182) to achieve safety. This study compared the growth potential of Listeria monocytogenes on cheeses manufactured from raw or pasteurized milk and held for > 60 days at 4 degrees C. Final cheeses were within federal Standards of Identity for soft ripened cheese, with low moisture targets to facilitate the holding period. Wheels were surface inoculated with a five-strain cocktail of L. monocytogenes at approximately 0.2 CFU/ cm2 (low level) or 2 CFU/cm2 (high level), ripened, wrapped, and held at 4 degrees C. Listeria populations began to increase by day 28 for all treatments after initial population declines. From the low initial inoculation level, populations in raw and pasteurized milk cheese reached maximums of 2.96 +/- 2.79 and 2.33 +/- 2.10 log CFU/g, respectively, after 60 days of holding. Similar growth was observed in cheese inoculated at high levels, where populations reached 4.55 +/- 4.33 and 5.29 +/- 5.11 log CFU/g for raw and pasteurized milk cheeses, respectively. No significant differences (P < 0.05) were observed in pH development, growth rate, or population levels between cheeses made from the different milk types. Independent of the milk type, cheeses held for 60 days supported growth from very low initial levels of L. monocytogenes introduced as a postprocess contaminant. The safety of cheeses of this type must be achieved through control strategies other than aging, and thus revision of current federal regulations is warranted.
Maryanne Drake - One of the best experts on this subject based on the ideXlab platform.
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Milk fat threshold determination and the effect of milk fat content on consumer preference for fluid milk.
Journal of dairy science, 2017Co-Authors: K.s. Mccarthy, K. Lopetcharat, Maryanne DrakeAbstract:Milk consumption in the United States has been in decline since the 1960s. Milk fat plays a critical role in sensory properties of fluid milk. The first objective of this study was to determine the change in percent milk fat needed to produce a detectable or just noticeable difference (JND) to consumers in skim, 1%, 2%, and whole milks. The second objective was to evaluate how milk fat affected consumer preferences for fluid milk. Threshold tests were conducted to determine the JND for each reference milk (skim, 1%, 2%, and whole milk), with a minimum of 60 consumers for each JND. The JND was determined for milks by visual appearance without tasting and tasting without visual cues. Serving temperature effect (4, 8, or 15°C) on tasting JND values were also investigated. The established JND values were then used to conduct ascending forced-choice preference tests with milks. Consumers were assigned to 3 groups based on self-reported milk consumption: skim milk drinkers (n = 59), low-fat milk drinkers (consumed 1% or 2% milk, n = 64), and whole milk drinkers (n = 49). Follow-up interviews were conducted where consumers were asked to taste and explain their preference between milks that showed the most polarization within each consumer segment. Descriptive sensory analysis was performed on the milks used in the follow-up interviews to quantify sensory differences. Visual-only JND were lower than tasting-only JND values. Preference testing revealed 3 distinct preference curves among the consumer segments. Skim milk drinkers preferred skim milk and up to 2% milk fat, but disliked milk higher in fat due to it being "too thick," "too heavy," "flavor and texture like cream," "too fatty," and "looks like half and half." Low-fat milk drinkers preferred 2% milk up to 3.25% (whole milk), but then disliked higher milk fat content. Whole milk drinkers preferred whichever milk was higher in milk fat regardless of how high the fat content was, distinct from skim and low-fat milk drinkers. The findings of this study provide insights on sensory characteristics of milk fat in fluid milk and consumer sensory perception of these properties. These results also provide insights on how the industry might adjust milk fat references for adjusting milk sensory properties to increase milk preference and remain within the Standards of Identity of milk.
Catherine Gensler - One of the best experts on this subject based on the ideXlab platform.
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compatibility of commercially produced protective cultures with common cheesemaking cultures and their antagonistic effect on foodborne pathogens
Journal of Food Protection, 2020Co-Authors: Stephanie R B Brown, Catherine Gensler, Sulaiman F Aljasir, Dennis J DamicoAbstract:ABSTRACT The documented survival of pathogenic bacteria, including Listeria monocytogenes (LM), Shiga toxin-producing Escherichia coli (STEC), and Salmonella during the manufacture and aging of some cheeses highlights the need for additional interventions to enhance food safety. Unfortunately, few interventions are compliant with the Standards of Identity for cheese. Protective bacterial cultures (PCs) represent actionable, natural interventions. However, supportive data for commercially produced PCs regarding their efficacy against pathogens and potential antagonism with each other and cheesemaking cultures are scant, thereby impeding their potential use by the cheese industry. The overall objective of this study was to identify commercially produced PCs that exert antimicrobial activity toward pathogens with minimal impact on beneficial cheese microbes. Direct antagonism and agar well diffusion assays were used to determine the impact of 10 commercially produced PCs on the growth of starter cultures and cultures of ripening bacteria and fungi. Deferred antagonism was used to evaluate the potential for antimicrobial effects against LM, STEC, and Salmonella. PCs and starter cultures were cocultured in ultrahigh-temperature-processed milk to determine the effects of coculture on starter acidification profiles when incubated according to a simulated cheesemaking temperature profile (4 h at 35°C followed by 20 h at 20°C). Compatibility assays suggest that PC antagonism is microbe and strain specific. Only one PC negatively impacted the acidification of the starters tested. PC antagonism of ripening bacteria and fungi growth varied but was consistent within species. All PCs displayed deferred inhibition of LM, STEC, and Salmonella growth, but to varying degrees. These data identify commercial PCs with potential for the control of pathogens and characterize their compatibility with cheesemaking cultures for future use by cheesemakers and investigations of their efficacy in the production of cheese. HIGHLIGHTS
K.s. Mccarthy - One of the best experts on this subject based on the ideXlab platform.
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Milk fat threshold determination and the effect of milk fat content on consumer preference for fluid milk.
Journal of dairy science, 2017Co-Authors: K.s. Mccarthy, K. Lopetcharat, Maryanne DrakeAbstract:Milk consumption in the United States has been in decline since the 1960s. Milk fat plays a critical role in sensory properties of fluid milk. The first objective of this study was to determine the change in percent milk fat needed to produce a detectable or just noticeable difference (JND) to consumers in skim, 1%, 2%, and whole milks. The second objective was to evaluate how milk fat affected consumer preferences for fluid milk. Threshold tests were conducted to determine the JND for each reference milk (skim, 1%, 2%, and whole milk), with a minimum of 60 consumers for each JND. The JND was determined for milks by visual appearance without tasting and tasting without visual cues. Serving temperature effect (4, 8, or 15°C) on tasting JND values were also investigated. The established JND values were then used to conduct ascending forced-choice preference tests with milks. Consumers were assigned to 3 groups based on self-reported milk consumption: skim milk drinkers (n = 59), low-fat milk drinkers (consumed 1% or 2% milk, n = 64), and whole milk drinkers (n = 49). Follow-up interviews were conducted where consumers were asked to taste and explain their preference between milks that showed the most polarization within each consumer segment. Descriptive sensory analysis was performed on the milks used in the follow-up interviews to quantify sensory differences. Visual-only JND were lower than tasting-only JND values. Preference testing revealed 3 distinct preference curves among the consumer segments. Skim milk drinkers preferred skim milk and up to 2% milk fat, but disliked milk higher in fat due to it being "too thick," "too heavy," "flavor and texture like cream," "too fatty," and "looks like half and half." Low-fat milk drinkers preferred 2% milk up to 3.25% (whole milk), but then disliked higher milk fat content. Whole milk drinkers preferred whichever milk was higher in milk fat regardless of how high the fat content was, distinct from skim and low-fat milk drinkers. The findings of this study provide insights on sensory characteristics of milk fat in fluid milk and consumer sensory perception of these properties. These results also provide insights on how the industry might adjust milk fat references for adjusting milk sensory properties to increase milk preference and remain within the Standards of Identity of milk.
Stephanie R B Brown - One of the best experts on this subject based on the ideXlab platform.
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compatibility of commercially produced protective cultures with common cheesemaking cultures and their antagonistic effect on foodborne pathogens
Journal of Food Protection, 2020Co-Authors: Stephanie R B Brown, Catherine Gensler, Sulaiman F Aljasir, Dennis J DamicoAbstract:ABSTRACT The documented survival of pathogenic bacteria, including Listeria monocytogenes (LM), Shiga toxin-producing Escherichia coli (STEC), and Salmonella during the manufacture and aging of some cheeses highlights the need for additional interventions to enhance food safety. Unfortunately, few interventions are compliant with the Standards of Identity for cheese. Protective bacterial cultures (PCs) represent actionable, natural interventions. However, supportive data for commercially produced PCs regarding their efficacy against pathogens and potential antagonism with each other and cheesemaking cultures are scant, thereby impeding their potential use by the cheese industry. The overall objective of this study was to identify commercially produced PCs that exert antimicrobial activity toward pathogens with minimal impact on beneficial cheese microbes. Direct antagonism and agar well diffusion assays were used to determine the impact of 10 commercially produced PCs on the growth of starter cultures and cultures of ripening bacteria and fungi. Deferred antagonism was used to evaluate the potential for antimicrobial effects against LM, STEC, and Salmonella. PCs and starter cultures were cocultured in ultrahigh-temperature-processed milk to determine the effects of coculture on starter acidification profiles when incubated according to a simulated cheesemaking temperature profile (4 h at 35°C followed by 20 h at 20°C). Compatibility assays suggest that PC antagonism is microbe and strain specific. Only one PC negatively impacted the acidification of the starters tested. PC antagonism of ripening bacteria and fungi growth varied but was consistent within species. All PCs displayed deferred inhibition of LM, STEC, and Salmonella growth, but to varying degrees. These data identify commercial PCs with potential for the control of pathogens and characterize their compatibility with cheesemaking cultures for future use by cheesemakers and investigations of their efficacy in the production of cheese. HIGHLIGHTS