Modeling to control spores in raw milk

A modeling approach was used to identify measures at the farm that reduce transmission of microorganisms to raw milk. Butyric acid bacteria (BAB) and Bacillus cereus were used as case-studies. Minimizing the concentration of BAB spores in raw milk is important to prevent late-blowing of Gouda-type cheeses. Reducing the concentration of B. cereus spores in raw milk increases the shelf life of refrigerated pasteurized dairy products.First, predictive models were developed based on a translation of contamination pathways into chains of unit-operations. Via simulations, strategies were identified to control spore concentrations in farm tank milk (FTM)below 1,000 spores/L.Subsequently, the identified strategies were validated using data from a year-long field survey held at 24 Dutch farms.The results of this study show that mathematical modeling is very useful to identify effective measures to reduce the contamination of FTM with spores. The control strategies derived using model simulations were in agreement with results from the field survey. The following general conclusions were drawn:·       To minimize the concentration of BAB spores in FTM, it is by far most important to prevent growth of BAB in grass- and corn-silage. Farmers should aim for a concentration in grass- and corn-silage fed to cowsbelow 1,000 spores/g. To achieve this, it is essential to prevent oxygen penetration into the silage silo and to remove molded and deteriorated silage from the ration fed to the cows. Measures aimed at other parts of the contamination pathway, such as teat cleaning prior to milking, are much less effective.·       The concentration of B. cereus spores in FTM isnormally below 1,000 spores/L.During housing and pasturing spores of B. cereus in FTM originate from feeds. Two critical factors could lead to concentrations above 1,000 spores/L. Firstly, the contamination teats with soil is a high risk because soil can contain high concentrations of B. cereus spores. Secondly, build-up of B. cereus in improperly cleaned milking equipment could lead to high spore concentrations in FTM.·       Implementation of the measures identified in this study could make late-blowing of Gouda-type cheeses a rare incident and prolong the shelf life of refrigerated pasteurized consumer milk by approximately 10%.A modeling approach was used to identify measures at the farm that reduce transmission of microorganisms to raw milk. Spores of butyric acid bacteria (BAB) and Bacillus cereus were used as case-studies because of their relevance for the Dutch dairy industry..The following general conclusions were drawn:·       To minimize the concentration of BAB spores in FTM, it is by far most important to prevent growth of BAB in grass- and corn-silage. Farmers should aim for a concentration in grass- and corn-silage fed to cowsbelow 1,000 spores/g. To achieve this, it is essential to prevent oxygen penetration into the silage silo and to remove molded and deteriorated silage from the ration fed to the cows. Measures aimed at other parts of the contamination pathway, such as teat cleaning prior to milking, are much less effective.·       The concentration of B. cereus spores in FTM isnormally below 1,000 spores/L.During housing and pasturing spores of B. cereus in FTM originate from feeds. Two critical factors could lead to concentrations above 1,000 spores/L. Firstly, the contamination teats with soil is a high risk because soil can contain high concentrations of B. cereus spores. Secondly, build-up of B. cereus in improperly cleaned milking equipment could lead to high spore concentrations in FTM.·       Implementation of the measures identified in this study could make late-blowing of Gouda-type cheeses a rare incident and prolong the shelf life of refrigerated pasteurized consumer milk by approximately 10%.

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Bibliographic Details
Main Author: Vissers, M.
Other Authors: Lankveld, J.M.G.
Format: Doctoral thesis biblioteca
Language:English
Subjects:bacillus cereus, bacterial spores, butyric acid bacteria, dairy hygiene, food contamination, microbial contamination, milk hygiene, raw milk, simulation models, bacteriële sporen, boterzuurbacteriën, melkhygiëne, microbiële besmetting, rauwe melk, simulatiemodellen, voedselbesmetting, zuivelhygiëne,
Online Access:https://research.wur.nl/en/publications/modeling-to-control-spores-in-raw-milk
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Summary:A modeling approach was used to identify measures at the farm that reduce transmission of microorganisms to raw milk. Butyric acid bacteria (BAB) and Bacillus cereus were used as case-studies. Minimizing the concentration of BAB spores in raw milk is important to prevent late-blowing of Gouda-type cheeses. Reducing the concentration of B. cereus spores in raw milk increases the shelf life of refrigerated pasteurized dairy products.First, predictive models were developed based on a translation of contamination pathways into chains of unit-operations. Via simulations, strategies were identified to control spore concentrations in farm tank milk (FTM)below 1,000 spores/L.Subsequently, the identified strategies were validated using data from a year-long field survey held at 24 Dutch farms.The results of this study show that mathematical modeling is very useful to identify effective measures to reduce the contamination of FTM with spores. The control strategies derived using model simulations were in agreement with results from the field survey. The following general conclusions were drawn:·       To minimize the concentration of BAB spores in FTM, it is by far most important to prevent growth of BAB in grass- and corn-silage. Farmers should aim for a concentration in grass- and corn-silage fed to cowsbelow 1,000 spores/g. To achieve this, it is essential to prevent oxygen penetration into the silage silo and to remove molded and deteriorated silage from the ration fed to the cows. Measures aimed at other parts of the contamination pathway, such as teat cleaning prior to milking, are much less effective.·       The concentration of B. cereus spores in FTM isnormally below 1,000 spores/L.During housing and pasturing spores of B. cereus in FTM originate from feeds. Two critical factors could lead to concentrations above 1,000 spores/L. Firstly, the contamination teats with soil is a high risk because soil can contain high concentrations of B. cereus spores. Secondly, build-up of B. cereus in improperly cleaned milking equipment could lead to high spore concentrations in FTM.·       Implementation of the measures identified in this study could make late-blowing of Gouda-type cheeses a rare incident and prolong the shelf life of refrigerated pasteurized consumer milk by approximately 10%.A modeling approach was used to identify measures at the farm that reduce transmission of microorganisms to raw milk. Spores of butyric acid bacteria (BAB) and Bacillus cereus were used as case-studies because of their relevance for the Dutch dairy industry..The following general conclusions were drawn:·       To minimize the concentration of BAB spores in FTM, it is by far most important to prevent growth of BAB in grass- and corn-silage. Farmers should aim for a concentration in grass- and corn-silage fed to cowsbelow 1,000 spores/g. To achieve this, it is essential to prevent oxygen penetration into the silage silo and to remove molded and deteriorated silage from the ration fed to the cows. Measures aimed at other parts of the contamination pathway, such as teat cleaning prior to milking, are much less effective.·       The concentration of B. cereus spores in FTM isnormally below 1,000 spores/L.During housing and pasturing spores of B. cereus in FTM originate from feeds. Two critical factors could lead to concentrations above 1,000 spores/L. Firstly, the contamination teats with soil is a high risk because soil can contain high concentrations of B. cereus spores. Secondly, build-up of B. cereus in improperly cleaned milking equipment could lead to high spore concentrations in FTM.·       Implementation of the measures identified in this study could make late-blowing of Gouda-type cheeses a rare incident and prolong the shelf life of refrigerated pasteurized consumer milk by approximately 10%.