The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Tanya Roberts - One of the best experts on this subject based on the ideXlab platform.
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topics in microbial risk assessment dynamic flow tree process
Risk Analysis, 1998Co-Authors: Harry M Marks, Margaret E Coleman, Tanya RobertsAbstract:Microbial risk assessment is emerging as a new discipline in risk assessment. A systematic approach to microbial risk assessment is presented that employs data analysis for developing parsimonious models and accounts formally for the variability and uncertainty of model inputs using analysis of variance and Monte Carlo simulation. The purpose of the paper is to raise and examine issues in conducting microbial risk assessments. The enteric pathogen Escherichia coli O157:H7 was selected as an example for this study due to its significance to public health. The framework for our work is consistent with the risk assessment components described by the National Research Council in 1983 (hazard identification; exposure assessment; dose-response assessment; and risk characterization). Exposure assessment focuses on Hamburgers, cooked a range of temperatures from rare to well done, the latter typical for fast food restaurants. Features of the model include predictive microbiology components that account for random stochastic growth and death of organisms in Hamburger. For dose-response modeling, Shigella data from human feeding studies were used as a surrogate for E. coli O157:H7. Risks were calculated using a threshold model and an alternative nonthreshold model. The 95% probability intervals for risk of illness for product cooked to a given internal temperature spanned five orders of magnitude for these models. The existence of even a small threshold has a dramatic impact on the estimated risk.
Stephen R Mccoll - One of the best experts on this subject based on the ideXlab platform.
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quantitative risk assessment for escherichia coli o157 h7 in ground beef Hamburgers
International Journal of Food Microbiology, 1998Co-Authors: Michael H Cassin, Anna M Lammerding, Ewen C D Todd, William H Ross, Stephen R MccollAbstract:Abstract Quantitative Risk Assessment (QRA) is a methodology used to organize and analyze scientific information to estimate the probability and severity of an adverse event. Applied to microbial food safety, the methodology can also help to identify those stages in the manufacture, distribution, handling, and consumption of foods that contribute to an increased risk of foodborne illness, and help focus resources and efforts to most effectively reduce the risk of foodborne pathogens. The term Process Risk Model (PRM) is introduced in this paper to describe the integration and application of QRA methodology with scenario analysis and predictive microbiology to provide an objective assessment of the hygienic characteristics of a manufacturing process. The methodology was applied to model the human health risk associated with Escherichia coli O157:H7 in ground beef Hamburgers. The PRM incorporated two mathematical submodels; the first was intended to described the behaviour of the pathogen from the production of the food through processing, handling, and consumption to predict human exposure. The exposure estimate was then used as input to a dose–response model to estimate the health risk associated with consuming food from the process. Monte Carlo simulation was used to assess the effect of the uncertainty and variability in the model parameters on the predicted human health risk. The model predicted a probability of Hemolytic Uremic Syndrome of 3.7×10−6 and a probability of mortality of 1.9×10−7 per meal for the very young. These estimates are likely high for all Hamburger meals, but may be reasonable for the home-prepared Hamburgers described by this model. The efficacy of three risk mitigation strategies were evaluated by modifying the values of the predictive factors and comparing the new predicted risk. The average probability of illness was predicted to be reduced by 80% under a hypothetical mitigation strategy directed at reducing microbial growth during retail storage through a reduction in storage temperature. This strategy was predicted to be more effective than a hypothetical intervention which estimated a plausible reduction in the concentration of E. coli O157:H7 in the feces of cattle shedding the pathogen and one aimed at convincing consumers to cook Hamburgers more thoroughly. The conclusions of this approach are only accurate to the extent that the model accurately represents the process. Currently, uncertainty and ignorance about the hygienic effects of the individual operations during production, processing, and handling limit the applicability of a PRM to specify HACCP criteria in a quantitative manner. However, with continuous improvement through stimulated research, a PRM should encompass all available information about the process, food, and pathogen and should be the most appropriate decision-support tool since it represents current knowledge.
Farhad Jafari - One of the best experts on this subject based on the ideXlab platform.
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Hamburger moment sequences and their moment subsequences
Linear & Multilinear Algebra, 2016Co-Authors: Saroj Aryal, Hayoung Choi, Farhad JafariAbstract:Partial sequences and subsequences of Hamburger moment sequences arise where data have been lost or interpolation is sought. All the relevant questions dealing with full moment sequences, such as positivity and partial positivity, relationship between the corresponding measures and determinacy can be posed for the partial data. In this paper, we characterize the moment subsequences of Hamburger moment sequences, give a description of certain completable patterns of partial sequences and provide a simple relationship between the Cauchy transform of the moment sequence and its moment subsequences. A general result for perturbation of moment sequences by arbitrary sequences is also given.
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Sparse Hamburger Moment Sequences and Completions in Several Variables
arXiv: Functional Analysis, 2016Co-Authors: Saroj Aryal, Hayoung Choi, Farhad JafariAbstract:Putinar and Vasilescu have given an algebraic characterization of Hamburger moment sequences in several variables. In this paper we give a characterization of sparse moment subsequences of Hamburger moment sequences and consider the problem of completion of these moment subsequences.
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Hamburger moment sequences and their moment subsequences
arXiv: Functional Analysis, 2016Co-Authors: Saroj Aryal, Hayoung Choi, Farhad JafariAbstract:In this paper a connection between Hamburger moment sequences and their moment subsequences is given and the determinacy of these problems are related.
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Positive definite Hankel matrix completions and Hamburger moment completions
Linear Algebra and its Applications, 2016Co-Authors: Hayoung Choi, Farhad JafariAbstract:Abstract In this paper we give solutions to Hamburger moment problems with missing entries. The problem of completing partial positive sequences is considered. The main result is a characterization of positive definite completable patterns, namely patterns that guarantee the existence of Hamburger moment completion of a partial positive definite sequence. Moreover, several patterns which are not positive definite completable are given.
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Sparse Hamburger Moment Sequences
arXiv: Classical Analysis and ODEs, 2012Co-Authors: Saroj Aryal, Hayoung Choi, Farhad JafariAbstract:Putinar and Vasilescu [6] have given an algebraic characterization of Hamburger moment sequences in several variables. In this paper we study some sparse moment subsequences of Hamburger moment sequences and consider the problem of completion of these moment subsequences.
David Heber - One of the best experts on this subject based on the ideXlab platform.
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hass avocado modulates postprandial vascular reactivity and postprandial inflammatory responses to a Hamburger meal in healthy volunteers
Food & Function, 2013Co-Authors: Zhaoping Li, Susanne M Henning, Yanjun Zhang, Alona Zerlin, Gail Thames, Susan Bowerman, Angela M Wong, Alexis Jones, Chihong Tseng, David HeberAbstract:Hass avocados are rich in monounsaturated fatty acids (oleic acid) and antioxidants (carotenoids, tocopherols, polyphenols) and are often eaten as a slice in a sandwich containing Hamburger or other meats. Hamburger meat forms lipid peroxides during cooking. After ingestion, the stomach functions as a bioreactor generating additional lipid peroxides and this process can be inhibited when antioxidants are ingested together with the meat. The present pilot study was conducted to investigate the postprandial effect of the addition of 68 g of avocado to a Hamburger on vasodilation and inflammation. Eleven healthy subjects on two separate occasions consumed either a 250 g Hamburger patty alone (ca. 436 cal and 25 g fat) or together with 68 grams of avocado flesh (an additional 114 cal and 11 g of fat for a total of 550 cal and 36 g fat), a common culinary combination, to assess effects on vascular health. Using the standard peripheral arterial tonometry (PAT) method to calculate the PAT index, we observed significant vasoconstriction 2 hours following Hamburger ingestion (2.19 ± 0.36 vs. 1.56 ± 0.21, p = 0.0007), which did not occur when the avocado flesh was ingested together with the burger (2.17 ± 0.57 vs. 2.08 ± 0.51, NS p = 0.68). Peripheral blood mononuclear cells were isolated from postprandial blood samples and the Ikappa-B alpha (IκBα) protein concentration was determined to assess effects on inflammation. At 3 hours, there was a significant preservation of IκBα (131% vs. 58%, p = 0.03) when avocado was consumed with the meat compared to meat alone, consistent with reduced activation of the NF-kappa B (NFκB) inflammatory pathway. IL-6 increased significantly at 4 hours in postprandial serum after consumption of the Hamburger, but no change was observed when avocado was added. Postprandial serum triglyceride concentration increased, but did not further increase when avocado was ingested with the burger compared to burger alone despite the added fat and calories from the avocado. These observations are suggestive of beneficial anti-inflammatory and vascular health effects of ingesting added Hass avocado with a Hamburger patty.
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antioxidant rich spice added to Hamburger meat during cooking results in reduced meat plasma and urine malondialdehyde concentrations
The American Journal of Clinical Nutrition, 2010Co-Authors: Zhaoping Li, Susanne M Henning, Yanjun Zhang, Alona Zerlin, Luyi Li, Hannah Karp, Gail Thames, Susan Bowerman, David HeberAbstract:Background: Emerging science has shown the effect of oxidation products and inflammation on atherogenesis and carcinogenesis. Cooking Hamburger meat can promote the formation of malondialdehyde that can be absorbed after ingestion. Objective:We studied the effect of an antioxidant spice mixture on malondialdehyde formation while cooking Hamburger meat and its effects on plasma and urinary malondialdehyde concentrations. Design: Eleven healthy volunteers consumed 2 kinds of burgers in a randomized order: one burger was seasoned with a spice blend, and one burger was not seasoned with the spice blend. The production of malondialdehyde in burgers and malondialdehyde concentrations in plasma and urine after ingestion were measured by HPLC. Results:Rosmarinic acid from oregano was monitored to assess the effect of cooking on spice antioxidant content. Forty percent (19 mg) of the added rosmarinic acid remained in the spiced burger (SB) after cooking. There was a 71% reduction in the malondialdehyde concentration (mean ± SD: 0.52 ± 0.02 μmol/250 g) in the meat of the SBs compared with the malondialdehyde concentration (1.79 ± 0.17 μmol/250 g) in the meat of the control burgers (CBs). The plasma malondialdehyde concentration increased significantly in the CB group as a change from baseline (P = 0.026). There was a significant time-trend difference (P = 0.013) between the 2 groups. Urinary malondialdehyde concentrations (μmol/g creatinine) decreased by 49% (P = 0.021) in subjects consuming the SBs compared with subjects consuming the CBs. Conclusions: The overall effect of adding the spice mixture to Hamburger meat before cooking was a reduction in malondialdehyde concentrations in the meat, plasma, and urine after ingestion. Therefore, cooking Hamburgers with a polyphenol-rich spice mixture can significantly decrease the concentration of malondialdehyde, which suggests potential health benefits for atherogenesis and carcinogenesis. This trial was registered at clinical trials.gov as {"type":"clinical-trial","attrs":{"text":"NCT01027052","term_id":"NCT01027052"}}NCT01027052.
Solveig Langsrud - One of the best experts on this subject based on the ideXlab platform.
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Hamburger hazards and emotions
Appetite, 2014Co-Authors: Nina Veflen Olsen, Elin Rossvoll, Solveig Langsrud, Joachim ScholdererAbstract:Previous studies indicate that many consumers eat rare Hamburgers and that information about microbiological hazards related to undercooked meat not necessarily leads to more responsible behavior. With this study we aim to investigate whether consumers’ willingness to eat Hamburgers depends on the emotions they experience when confronted with the food. A representative sample of 1046 Norwegian consumers participated in an online experiment. In the first part, participants were randomly divided into two groups. One group was confronted with a picture of a rare Hamburger, whereas the other group was confronted with a picture of a well-done Hamburger. The respondents were instructed to imagine that they were served the Hamburger on the picture and then to indicate which emotions they experienced: fear, disgust, surprise, interest, pleasure, or none of these. In part two, all respondents were confronted with four pictures of Hamburgers cooked to different degrees of doneness (rare, medium rare, medium well-done, well-done), and were asked to state their likelihood of eating. We analyzed the data by means of a multivariate probit model and two linear fixed-effect models. The results show that confrontation with rare Hamburgers evokes more fear and disgust than confrontation with well-done Hamburgers, that all Hamburgers trigger pleasure and interest, and that a consumer’s willingness to eat rare Hamburgers depends on the particular type of emotion evoked. These findings indicate that emotions play an important role in a consumer’s likelihood of eating risky food, and should be considered when developing food safety strategies.
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Consumer preferences, internal color and reduction of shigatoxigenic Escherichia coli in cooked Hamburgers.
Meat Science, 2014Co-Authors: Elin Rossvoll, Nina Veflen Olsen, Oddvin Sørheim, Even Heir, Trond Møretrø, Solveig LangsrudAbstract:Abstract The aim of this study was to relate consumer preferences and preparation of Hamburgers to color change, internal temperature and reduction of shigatoxigenic Escherichia coli (STEC) serogroups O157 and the “Big Six” (O26, O45, O103, O111, O121, O145) under two ground beef packaging scenarios: 75% O 2 MAP and vacuum. 75% O 2 MAP Hamburgers cooked to 60 °C core temperature appeared done and showed less internal red color (lower a*) than corresponding vacuum Hamburgers. Similar STEC reduction ( 10 ) was found for both Hamburgers at core temperatures ≤ 66 °C. In a representative survey (N = 1046) most consumers reported to judge Hamburger doneness by the color and many preferred undercooked Hamburgers. Premature browning of 75% O 2 MAP Hamburgers represents a risk of foodborne illness, when considering consumers' food handling practices. The risk is even greater if such ground beef is prepared by consumers who prefer undercooked Hamburgers and judge doneness by color.
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Consumer preferences, internal color and reduction of shigatoxigenic Escherichia coli in cooked Hamburgers.
Meat science, 2013Co-Authors: Elin Rossvoll, Nina Veflen Olsen, Oddvin Sørheim, Even Heir, Trond Møretrø, Solveig LangsrudAbstract:The aim of this study was to relate consumer preferences and preparation of Hamburgers to color change, internal temperature and reduction of shigatoxigenic Escherichia coli (STEC) serogroups O157 and the "Big Six" (O26, O45, O103, O111, O121, O145) under two ground beef packaging scenarios: 75% O2 MAP and vacuum. 75% O2 MAP Hamburgers cooked to 60 °C core temperature appeared done and showed less internal red color (lower a*) than corresponding vacuum Hamburgers. Similar STEC reduction (
