Author
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Hakk, Heldur |
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Lupton, Sara |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 9/22/2015 Publication Date: 11/3/2015 Citation: Hakk, H., Lupton, S.J. 2015. Understanding the potential impact of milk processing on the distribution of POPs residues in milk products [abstract]. Recent Advances in Food Analysis. p. 140. Interpretive Summary: It has long been acknowledged that human exposure to persistent organic pollutants (POPs) occurs principally through our food. Therefore, market basket surveys of the food supply have been valuable tools to provide estimates of human exposures to POPs and the risks associated with these exposures. However, very little is known about how POPs may be distributed in food products during processing events. It would be a safe assumption that lipophilic compounds, such as POPs, would distribute into lipophilic compartments during processing if such compartments are available. Thus, a contaminant’s log Kow may be a valuable predictor when modeling the behavior of contaminants in aqueous:lipid mixtures. However, these types of data have not been generated for POPs that may be present in milk, and therefore, it is not known if milk, a complex matrix consisting of fat globules, proteins of various molecular weights, sugars, and water, can be treated simply as an aqueous:lipid mixture. Data will be presented on how a representative dioxin, PCB, and two brominated flame retardants partition into skim milk, milk fat, curd, whey, and concentrated whey proteins (retentate) in a lab-scale simulation of whole milk processing Four 14C-labeled POPs, 1,2,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 2,3’,4,4’,5-pentachlorobiphenyl (PCB 118); ß-hexabromocyclododecane (HBCDD); and tetrabromobisphenol-A (TBBP-A) were used for this study. Greater than 80% of the fortified TCDD, PCB-118, and ß-HBCDD distributed into the milk fat fraction. Specifically, milk fat (and skim milk) consisted of 84.2% ± 3.6 (6.9% ± 1.7), 83.5% ± 3.4 (4.6% ± 0.7), and 87.2% ± 2.0 (3.5 ± 0.4%) of TCDD, PCB 118, and HBCDD after a 30 min incubation, respectively. However, TBBP-A distributed evenly between milk fat and skim milk, i.e. 46.4 ± 0.8% and 45.3 ±1.3%, respectively. Skim milk was subjected to curding processes, and =85% of the remaining contaminants concentrated in the curd while 10-15% partitioned into the whey fraction. TBBP-A was an exception since 45% of the remaining dose distributed to the curd and 55% was in the whey. Ultrafiltration of the whey resulted in =85% of the remaining contaminants concentrating in whey protein retentate for all POPs used. The POPs chosen for the study had log Kow values ranging from 6.8-7.58 (TCDD), 3.2-6.4 (TBBP-A), 5.12-6.6 (HBCDD), and 7.12 (PCB-118) and these values were used to evaluate the contaminant distribution between milk fat and skim milk compared to the log ([POP]milk fat/[POP]skim milk). From preliminary results, log Kow alone does not explain the distribution of these contaminants into specific milk fractions. Furthermore, depending on the POP, milk fraction distribution data indicated that processing can result in contaminant concentration increases in finished milk products. Technical Abstract: It has long been acknowledged that human exposure to persistent organic pollutants (POPs) occurs principally through our food. Therefore, market basket surveys of the food supply have been valuable tools to provide estimates of human exposures to POPs and the risks associated with these exposures. However, very little is known about how POPs may be distributed in food products during processing events. It would be a safe assumption that lipophilic compounds, such as POPs, would distribute into lipophilic compartments during processing if such compartments are available. Thus, a contaminant’s log Kow may be a valuable predictor when modeling the behavior of contaminants in aqueous:lipid mixtures. However, these types of data have not been generated for POPs that may be present in milk, and therefore, it is not known if milk, a complex matrix consisting of fat globules, proteins of various molecular weights, sugars, and water, can be treated simply as an aqueous:lipid mixture. Data will be presented on how a representative dioxin, PCB, and two brominated flame retardants partition into skim milk, milk fat, curd, whey, and concentrated whey proteins (retentate) in a lab-scale simulation of whole milk processing Four 14C-labeled POPs, 1,2,7,8-tetrachlorodibenzo-p-dioxin (TCDD); 2,3’,4,4’,5-pentachlorobiphenyl (PCB 118); ß-hexabromocyclododecane (HBCDD); and tetrabromobisphenol-A (TBBP-A) were used for this study. Greater than 80% of the fortified TCDD, PCB-118, and ß-HBCDD distributed into the milk fat fraction. Specifically, milk fat (and skim milk) consisted of 84.2% ± 3.6 (6.9% ± 1.7), 83.5% ± 3.4 (4.6% ± 0.7), and 87.2% ± 2.0 (3.5 ± 0.4%) of TCDD, PCB 118, and HBCDD after a 30 min incubation, respectively. However, TBBP-A distributed evenly between milk fat and skim milk, i.e. 46.4 ± 0.8% and 45.3 ±1.3%, respectively. Skim milk was subjected to curding processes, and =85% of the remaining contaminants concentrated in the curd while 10-15% partitioned into the whey fraction. TBBP-A was an exception since 45% of the remaining dose distributed to the curd and 55% was in the whey. Ultrafiltration of the whey resulted in =85% of the remaining contaminants concentrating in whey protein retentate for all POPs used. The POPs chosen for the study had log Kow values ranging from 6.8-7.58 (TCDD), 3.2-6.4 (TBBP-A), 5.12-6.6 (HBCDD), and 7.12 (PCB-118) and these values were used to evaluate the contaminant distribution between milk fat and skim milk compared to the log ([POP]milk fat/[POP]skim milk). From preliminary results, log Kow alone does not explain the distribution of these contaminants into specific milk fractions. Furthermore, depending on the POP, milk fraction distribution data indicated that processing can result in contaminant concentration increases in finished milk products. |
