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Deconvolution of the Error Associated with Random Sampling

Advances in Pure Mathematics 2019年第3期9卷 205-227页

作者： Peter L. Irwin Yiping He Chin-Yi Chen Molecular Characterization of Foodborne Pathogens United States Department of Agriculture Wyndmoor PA USA

In this work empirical models describing sampling error (Δ) are reported based upon analytical findings elicited from 3 common probability density functions (PDF): the Gaussian, representing any real-valued, randomly changing variable x of mean μ?and standard deviation σthe Poisson, representing counting data: i.e., any integral-valued entity’s count of x (cells, clumps of cells or colony forming units, molecules, mutations, etc.) per tested volume, area, length of time, etc. with population mean of μ?and;binomial data representing the number of successful occurrences of something (x+) out of n observations or sub-samplings. These data were generated in such a way as to simulate what should be observed in practice but avoid other forms of experimental error. Based upon analyses of 104 Δ?measurements, we show that the average Δ?() is proportional to ?(σx•μ-1;Gaussian) or ?(Poisson & binomial). The average proportionality constants associated with these disparate populations were also nearly identical (;±s). However, since ?for any Poisson process, . In a similar vein, we have empirically demonstrated that binomial-associated ?were also proportional to σx•μ-1. Furthermore, we established that, when all ?were plotted against either ?or σx•μ-1, there was only one relationship with a slope = A (0.767 ± 0.0990) and a near-zero intercept. This latter finding also argues that all , regardless of parent PDF, are proportional to σx•μ-1?which is the coefficient of variation for a population of sample means (). Lastly, we establish that the proportionality constant A is equivalent to the coefficient of variation associated with Δ?() measurement and, therefore, . These results are noteworthy inasmuch as they provide a straightforward empirical link between stochastic sampling error and the aforementioned Cvs. Finally, we demonstrate that all attendant empirical measures of Δ?a

关键词： Stochastic Sampling Error Modeling Most Probable Composition Quantitative Metagenomics Food-Borne Bacteria

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The effect of milling on proteins in model Queso Fresco cheeses

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Advances in Bioscience and Biotechnology 2012年第1期3卷 1-6页

作者： Moushumi Paul Alberto Nunez Diane Van Hekken Eastern Regional Research Center Agricultural Research ServiceUS Department of AgricultureWyndmoorUSA

Raw milk Queso Fresco (QF) made in Mexico contains contaminating bacterial strains that are not permitted in US foods. There is interest in developing a pasteurized milk version of Mexican Queso Fresco to be sold in the US. Milling is one of many manufacturing factors that may influence protein integrity. The aim of this study is to assess the effect of milling procedures on protein composition and cheese functional properties in a model QF, made without starter cultures. Mass spectrometric and gel electrophoretic analyses of aged milled cheeses show minimal changes in protein content without differences among the milling techniques. In these novel QF-like cheeses, eight weeks of aging, regardless of milling type, results in cheeses that is very similar to the non-aged samples. Aged cheeses with minimal proteolysis imply an extended shelf life and therefore, model cheeses from this study, relative to Mexican raw milk cheeses, would stay fresher in American households and supermarkets longer.

关键词： Queso Fresco Cheese Milling Proteolysis Mass Spectrometry

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Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds

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Nuclear Science and Techniques 2006年第2期17卷 83-85页

作者： LI Nai-Nin D. W. THAYER R. GATES D. SCHWARTZ R. RICHARDSON Institute of Atomic Energy Application Jiangsu Academy of Agricultural Sciences （JAAS） Nanjing 210014 China Food Safety Research United States Department of Agriculture Agricultural Research Service Eastern Regional Research Center 600 East Mermaid lane Wyndmoor Pennsylvania 19038 USA

A kind of alfalfa seeds was irradiated by 1, 2, 3, 4 and 5 kGy at a dose rate of 6.288 kGy·h-1 in a self-shielded irradiator of 137Cs gamma rays. The EPR spectra, which were measured subsequently between 0.3401 and 0.3501 T, showed that there was a direct proportional relationship between the EPR signal strength of free radi- cals produced by gamma irradiation in the alfalfa seeds and absorbed dose. The first derivative EPR spectra of the al- falfa seeds were very clear and easy to identify. However, the EPR signal strength of the peak-to-peak amplitude de- creased rapidly and most of them decayed beyond 50% within 3 days after the seeds were irradiated. It tended to sta- bilize after half a month since the seeds were irradiated. The differences of the EPR signal strength between the irra- diated and unirradiated alfalfa seeds still remained. All seeds were stored at ambient temperature for more than 3 months. Therefore, using EPR spectrometry technique to measure free radicals in alfalfa seeds as a means to deter- mine whether the seeds have been irradiated or not is feasible, relatively fast and simple.

关键词：紫花苜蓿种子 EPR光谱自由基 Gamma辐射

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Measuring the antioxidative activities of Queso Fresco after post-packaging high-pressure processing

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Advances in Bioscience and Biotechnology 2012年第4期3卷 297-303页

作者： Moushumi Paul Jeffrey D. Brewster Diane L. Van Hekken Peggy M. Tomasula Dairy and Functional Foods Research Unit USDA ARS NAA ERRC 600 East Mermaid Lane Wyndmoor PA USA Molecular Characterization of Foodborne Pathogens Research Unit USDA ARS NAA ERRC 600 East Mermaid Lane Wyndmoor PA USA

Some milk-associated proteins are known to be nutritionally valuable and form bioactive peptides that exhibit activity against hypertension and oxidative stress. Consumption of cheeses, such as the popular Hispanic-style cheese Queso Fresco (QF), may be a vehicle for delivery of these milk-associated peptides. This paper describes the effects of high-pressure processing (HPP) on the antioxidative activity (ORAC- FL value) of water-soluble proteins extracted from QF samples. QFs were manufactured according to a commercial-make procedure using pasteurized, homogenized milk, without added starter cultures. The cheese was cut into 45 × 45 × 150 mm3 blocks, double packaged in vacuum bags, and received the following HPP treatments: 200, 400, or 600 MPa for either 0, 5, 10, or 20 min, with warming to an internal temperature of either 22℃ or 40℃ prior to HPP treatment. Results show that the core temperature of the cheese during HPP directly affects the ORAC-FL value. The activities of the lower temperature cheeses are independent of time and pressure, and have a median ORAC-FL value of 27 trolox equivalents (TE). The higher temperature cheeses have higher ORAC-FL values ranging from 21.5 to 96.0 TE;the highest activity corresponded to the cheese held at 400 MPa for the longest time under pressure (20 min). The 600 MPa cheeses increase in activity with increasing time under pressure, but are less active than the control cheese. These results indicate that processing temperature and pressure are important factors in the antioxidative activity of these QF samples and further understanding of the roles of these variables may lead to the manufacture of healthier and more nutritious cheeses and dairy products.

关键词： ORAC-FL Assay Queso Fresco Antioxidant High Pressure Processing

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Value Added Products from Plant Processing

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Agricultural Sciences 2017年第8期8卷 857-867页

作者： Abduvaly Jonmurodov Jamshed Bobokalonov Surayo Usmanova Zayniddin Muhidinov Linshu Liu Chemistry Institute of the Tajikistan Academy of Sciences Dushanbe Tajikistan Eastern Regional Research Center ARS USDA Wyndmoor PA USA

Fat and wax (F&W) compounds have to be removed from raw plant materials before pectin and oligosaccharides (OS) can be isolated. In this research, the mixtures of F&W, and polyphenols and sugars were firstly separated from the roots of Eremurus hissaricus (Eremurus h.), and the byproducts of fruit processing, such as apple pomace, sunflower head residues, and grape seeds, etc., using hexane/ethanol or ethyl acetate as leaching reagents at various ratios of liquid to solid. The resultant mixtures were then extracted with an ethanol/water mixture to separate F&W from polyphenols and sugars. It was found that the F&W yield decreased in the sequence of apricot > apple > sunflower head residues > peach > pumpkin with 21.84% in apricot as the highest number. The amount of alcohol-water soluble compounds (AWSC), mainly polyphenols and sugars, decreased in the sequence of peach > sunflower head residues > apricot > pumpkin > apple. No inter-dependence of AWSC and F&W was identified.

关键词： Fats Waxes Pectin Fruit Pomace Sunflower Head Grape Seedss Grape Cake Eremurus hissaricus

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Impact of Chlorine, Temperature and Freezing Shock on the Survival Behavior of Escherichia coliO157:H7 on Ready-to-Eat Meats

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Food and Nutrition Sciences 2012年第4期3卷 530-538页

作者： Shiowshuh Sheen Cheng-An Hwang Vijay K. Juneja Food Safety and Intervention Technologies Research Unit USDA Agricultural Research Service Research Facility Eastern Regional Research Center Wyndmoor USA Residue Chemistry and Predictive Microbiology Research Unit USDA Agricultural Research Service Research Facility Eastern Regional Research Center Wyndmoor USA.

Foodborne pathogens continue to pose a potential food safety hazard in ready-to-eat (RTE) meat. Chlorine is commonly used to sanitize processing equipment where Escherichia coli O157:H7 (Ec) may survive and contaminate food products. The objective of this study was to characterize the survival behavior of Ec with different stresses on RTE meats. A multi-strain cocktail of Ec was pre-treated with freezing shock for 15 - 20 h and/or chlorine (0, 25, and 50 ppm) for one hour, and then inoculated onto RTE meat surfaces to obtain about 3.0 log CFU/g. Samples were stored at three abuse temperatures (12℃, 18℃, and 24℃) and Ec was enumerated during the storage. The freezing shock impact was studied using the Ec cocktail stored in a freezer overnight followed by chlorine exposure for one hour. The lag phase and growth rate of Ec were estimated using DMFit (Combase, Baranyi’s model). Results indicated that Ec growth was suppressed by chlorine treatment. Freezing shock was found to have little impact in terms of lag time and growth rate. The lag phase of Ec after exposure to 0 ppm of chlorine (50.3 h) was shorter than that of Ec treated with 25 ppm (54.6 h) and 50 ppm (164.1 h) at 12℃. However, the lag phase decreased with an increase in temperature, e.g. at 25 ppm, lag times were 54.6, 51.1 and 48.9 h for 12℃, 18℃ and 24℃, respectively. Lag times increased with an increase in chlorine concentration. At 24℃, lag times were 15.8, 48.9, and 52.4 h for 0, 25, and 50 ppm, respectively. The growth rate increased with an increase in temperature for 0 and 25 ppm chlorine levels, but decreased at 50 ppm level. Growth rate and lag phase as a function of temperature and chlorine concentration can be described by polynomial models and modified Ratkowsky-type and Zwietering-type models. Results of this study will contribute to risk assessment of RTE meats.

关键词： Chlorine Lag Time Growth Rate E. coli O157:H7 Modeling

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Observations of the Germination Behavior of Tilletia indicaTeliospores on the Soil Surface under Varying Simulated Environmental Conditions

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American Journal of Plant Sciences 2017年第11期8卷 2878-2897页

作者： Gary L. Peterson Dana K. Berner John G. Phillips USDA ARS Foreign Disease-Weed Science Research UnitFort Detrick USA USDA-ARS-North Atlantic Area Wyndmoor USA

A series of replicated growth chamber studies were conducted to determine the effects of soil type and simulated European temperature conditions from fall planting to anthesis in Hungary, United Kingdom, Italy and Norway on the initiation of Tilletia indica teliospore germination on the soil surface. A concurrent study examined effects on teliospore germination of a simulated temperature profile for Ciudad Obregon, Mexico, where Karnal bunt is known to occur. Three soil moisture treatments were tested;40.5% water holding capacity (WHC), 16.2% WHC and weekly fluctuation of soil WHC. Results suggest that soil type would not have a significant effect on germination during the cropping season. Under all conditions tested, some portion of the teliospore population remained dormant but viable throughout the entire season. In comparing Mexican and Hungarian temperature profiles, highest soil surface germination for the Hungarian profile was at 40.5% WHC during the first 30 days of the simulation (30 days after planting date). The highest germination for the Mexican profile was at the 16.2% WHC during the last 30 days of the study (time of anthesis).

关键词： Karnal Bunt Spore Survival Field Population Wheat Smut Partial Bunt

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Effects of Sodium Lactate on the Survival of Listeria Monocytogenes, Escherichia coliO157:H7, and Salmonellaspp. in Cooked Ham at Refrigerated and Abuse Temperatures

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Food and Nutrition Sciences 2011年第5期2卷 464-470页

作者： Cheng-An Hwang Shiowshuh Sheen Vijay Juneja Residue Chemistry and Predictive Microbiology Research Unit Eastern Regional Research Center Agricultural Research Service United States Department of Agriculture Wyndmoor USA

The objective of this study was to determine the effect of sodium lactate on the survival of Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. in cooked ham during storage at refrigerated and abuse temperatures. Cooked ham was added with 0% - 3% lactate, inoculated with a multiple-strain mixture of L. monocytogenes, E. coli O157: H7, or Salmonella spp. and stored at 4oC - 15oC for up to 35 day. The growth of the three pathogens was inhibited in ham containing 3% lactate, and no growth of E. coli O157: H7 and Salmonella spp. occurred at the lowest storage tem- peratures of 6 and 8oC, respectively. In ham containing no lactate, the average growth rates were 0.256 - 0.380 log CFU/day for L. monocytogenes at 4oC - 8oC, 0.242 - 0.315 log CFU/day for E. coli O157: H7 at 8oC - 15oC, and 0.249 - 0.328 log CFU/day for Salmonella spp. at 10oC - 15oC. The addition of 1% or 2% lactate significantly (P < 0.05) reduced the growth rates of the three pathogens, and the effect was more profound at lower temperatures. Salmonella spp. were more sensitive to the effect of lactate than L. monocytogenes and E. coli O157: H7. Polynomial models were developed to describe the growth rates of the three pathogens as affected by the lactate concentration and storage tem- perature. Results from this study demonstrate the effect of lactate on the growth of L. monocytogenes, E. coli O157: H7, and Salmonella spp. in cooked ham and indicate the effective lactate concentrations and storage temperatures that can be used to enhance the microbiological safety of ready-to-eat ham products.

关键词： Ham Lactate Listeria Monocytogenes Escherichia Coli O157: H7 Salmonella spp.

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Comparison of Methods for Extraction of Keratin from Waste Wool

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Agricultural Sciences 2016年第10期7卷 670-679页

作者： Eleanor M. Brown Kalgi Pandya Maryann M. Taylor Cheng-Kung Liu Biobased and Other Animal Co-Products Research Unit Eastern Regional Research Center Agricultural Research Service US Department of Agriculture Wyndmoor PA USA

The U.S. sheep industry, more than 80,000 producers of 40 million pounds of raw wool per year, is an important component of the meat industry. New methods for the treatment of domestic wool with keratin isolated from the unmarketable fraction of wool, and functionalized for water, oil, or insect repellency are needed. As a first step in the process, we are evaluating the effectiveness of keratin solubilization via relatively benign methods that use thioglycolic acid, bisulfite or sulfide to reduce disulfide bonds, peracetic acid or percarbonate to oxidize disulfides, and urea/thiourea as hydrogen bond disrupters. The procedures are compared in terms of quality of soluble protein, cost effectiveness, potential for upscaling, environmental and operator safety. Successful completion of this project will provide the basis for commercial development of such methods, followed by functional modification of the soluble keratin, and its application to textiles.

关键词： Waste Wool Keratin Extraction Economic Comparison

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Beneficial horticultural responses from the application of solar thermotherapy to mature Huanglongbing-affected citrus trees

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Horticultural Plant Journal 2021年第5期7卷 411-422页

作者： Cheryl M.Armstrong Melissa S.Doud Weiqi Luo Smita Raithore Elizabeth A.Baldwin Wei Zhao Anne Plotto Jinhe Bai John A.Manthey Ed Stover Yongping Duan United States Department of Agriculture-Agriculture Research Service-Eastern Regional Research Center WyndmoorPA 19038USA United States Department of Agriculture-Agriculture Research Service-United States Horticultural Research Laboratory Fort PierceFL 34945USA Center for Integrated Pest Management North Carolina State UniversityRaleighNC 27606USA Symrise AG TeterboroNJ 07608USA

The detrimental effects of Huanglongbing(HLB)on citrus are well known and so is the need for effective methods to combat this *** thermotherapy(ST),one of the management methods to help alleviate some of the negative effects of HLB,is the process of heating trees to therapeutic temperatures by encompassing the tree within a plastic structure(Visqueen)to harness the sun’s natural *** was applied to mature‘Valencia’citrus trees in three *** vigor,yield,and Candidatus Liberibacter asiaticus(Las)titer in leaves were monitored for two consecutive seasons post ST treatment,while fruit and juice quality were evaluated at the end of the second *** promoted an increase in canopy density in most groves tested and did not have a significant effect on fruit quantity,despite the prolonged exposure of the trees to increased ***,Las titer was reduced in both leaves and juice processed from affected trees post *** respect to fruit quality,the ratio of total soluble solids to titratable acidity was higher post ST compared to controls as was the sucrose content of the juice in most treated groves,whereas limonin was higher in juice from control *** components analysis of aroma volatiles showed significant differences between juice from treated versus control trees with volatiles imparting top-note and freshness to orange juice,such as acetaldehyde,hexanal,Z-3-hexenol and linalool,being higher in juice fromtreated *** panels confirmed that flavor differences existed,ultimately showing that ST resulted in improved juice flavor in well-managed *** the effects of ST on the trees appear temporary,such outcomes emphasize its utility when used as part of an integrated management strategy for HLB-affected citrus,imparting beneficial horticultural responses with minimal to positive effects on subsequent juice flavor.

关键词： HLB Candidatus Liberibacter asiaticus Thermotherapy Juice Flavor

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