Quality and Safety Assessment Research Unit

College Park, GA, United States

Quality and Safety Assessment Research Unit

College Park, GA, United States
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Liu Y.,Cotton Structure and Quality Research Unit | Thibodeaux D.,U.S. Department of Agriculture | Gamble G.,Quality and Safety Assessment Research Unit | Rodgers J.,Cotton Structure and Quality Research Unit
Textile Research Journal | Year: 2014

A fundamental understanding of the relationship between cotton fiber strength (or tenacity)/elongation and structure is important to help cotton breeders modify varieties for enhanced end-use qualities. In this study, the Stelometer instrument was used to measure the bundle fiber tenacity and elongation properties of different cotton fibers. This instrument is the traditional fiber strength reference method and could be still preferred as a screening tool owing to its significant low cost and portability. Fiber crystallinity (CIIR) and maturity (MIR) were characterized by the previously proposed attenuated total reflection (ATR)-based Fourier transform infrared protocol that has microsampling capability and is suitable for the tiny Stelometer breakage specimens (2 ∼ 5 mg), which cannot be readily analyzed by a conventional X-ray diffraction pattern. Relative to the distinctive increase in fiber tenacity with either CIIR or MIR for Pima fibers (Gossypium barbadense), there was an unclear trend between the two for Upland fibers (G. hirsutum). Although fiber elongation increases with elevated CIIR and MIR for Pima fibers, it generally decreases as CIIR and MIR increase for Upland fibers. Furthermore, small sets of Upland fibers with known varieties and growth areas were examined, and their responses to both CIIR and MIR are discussed briefly. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


Wu H.,Nanjing Agricultural University | Yan W.,Nanjing Agricultural University | Zhuang H.,Quality and Safety Assessment Research Unit | Huang M.,Nanjing Agricultural University | And 2 more authors.
Food Chemistry | Year: 2016

This study investigated the influence of partial substitution of NaCl with KCl on protein and lipid oxidation as well as antioxidant enzyme activities in dry-cured bacons during processing. The partial substitution was 0% KCl (I), 40% KCl (II), and 70% KCl (III). Compared with 0% KCl (I), the substitution of 40% NaCl with KCl did not significantly influence the protein and lipid oxidation and antioxidant enzyme activities. The bacons that were treated with 70% KCl treatment (III) showed increased lipid oxidation and antioxidant enzyme GSH-Px activity, whereas samples treated with formulas I and II showed higher protein oxidation and antioxidant enzyme catalase activity. These results demonstrate that the substitution of NaCl with KCl by more than 40% may significantly affect protein and lipid oxidation and that for the substitution of NaCl in further processed meat products with other chloride salts, salt content is very important for control of protein and lipid biochemical changes in finished products. © 2016 Elsevier Ltd. Ltd. All rights reserved.


Long M.,Nanjing Agricultural University | Wang J.,Nanjing Agricultural University | Zhuang H.,Quality and Safety Assessment Research Unit | Zhang Y.,Nanjing Agricultural University | And 2 more authors.
Food Control | Year: 2014

Under UV light, nano-TiO2 is effective in photocatalytic disinfection. In this paper, we studied the disinfection effects of nano-TiO2 on the two typical food-borne microorganisms, Gram-negative bacterium-Salmonella typhimurium and Gram-positive bacterium-Listeria monocytogenes, in meat products. Results show that nano-TiO2 had a strong disinfecting activity against both Gram-negative and Gram-positive pathogens in a suspension under UV light. L.monocytogenes was more resistant to nano-TiO2 treatment than Salmonella under UV light. Nano-TiO2 concentrations and initial bacteria populations had significant influence on the photocatalytic disinfection effectiveness against S.typhimurium. The optimum concentration (1.0g/L) was between 0.2g/L and 1.5g/L. Increasing S.typhimurium population from 104 to 107CFU/mL resulted in reduced photocatalytic disinfecting effectiveness by nano-TiO2. Electron microscope images revealed that nano-TiO2 photocatalytic disinfection starts with damaging the cell walls of bacteria. With serious destructions of cell walls, cell components released or defused out of cell from the damaged areas, and finally the cells completely lost their integrity and dissolved. These results demonstrate that nano-TiO2 is very effective against pathogens that can grow well on meat products and the effectiveness can be significantly influenced by nano-TiO2 contents and pathogen populations. The findings by these experiments provide the essential information for further developing a nano-metal-based, antimicrobial packaging system to improve safety of meat products. © 2013 Elsevier Ltd.


Wu H.,Nanjing Agricultural University | Zhuang H.,Quality and Safety Assessment Research Unit | Zhang Y.,Nanjing Agricultural University | Tang J.,Nanjing Agricultural University | And 4 more authors.
Food Chemistry | Year: 2014

This study investigated the influence of partial substitution of NaCl with KCl on the formation of volatile compounds in bacons during processing using a purge and trap dynamic headspace GC/MS system. Three substitutions were 0% KCl (I), 40% KCl (II), and 70% KCl (III). The profiles of the volatile compounds significantly changed during processing, particularly during the drying/ripening. At the end of process, the bacons from substitution III formed significantly higher levels of lipid-derived volatiles, such as straight chain aldehydes, hydrocarbons than bacons from substitution I and II, whereas the latter formed higher levels of volatiles from amino acid degradation such as 3-methylbutanal. There were very few differences in volatile formation between 0% and 40% KCl application. These results suggest that K+ substitution of Na+ by more than 40% may significantly change profiles of volatiles in finished dry-cured bacons and therefore would result in changes in the product aroma and/or flavour. © 2014 Elsevier Ltd. All rights reserved.


Holser R.A.,Quality and Safety Assessment Research Unit | Hawkins S.A.,Quality and Safety Assessment Research Unit
International Journal of Poultry Science | Year: 2011

Rapid measurement of a fatty acid supplement in poultry feed formulations was performed using near Infrared (NIR) spectroscopy with chemometric analysis. A standard feed formulation was amended with up to 10 wt% fatty acid supplement containing Docosahexaenoic Acid (DHA) and scanned from 10,000 cm 1 to 4000 cm -1. Spectra were evaluated by Principal Component Analysis (PCA) to detect outliers followed by Partial Least Square (PLS) regression. Models were developed with first derivative spectra. A typical dataset of 36 spectra was subdivided with 30 spectra used for model calibration and 6 spectra for the validation set. The PLS model produced a regression coefficient of 0.98314 with an RMSEC value of 0.44772. This technique provided a rapid method to analyze the amount of fatty acids in supplemented feeds. © Asian Network for Scientific Information, 2011.


Windham W.R.,Quality and Safety Assessment Research Unit | Yoon S.-C.,Quality and Safety Assessment Research Unit | Ladely S.R.,U.S. Department of Agriculture | Haley J.A.,Quality and Safety Assessment Research Unit | And 5 more authors.
Journal of Food Protection | Year: 2013

The U.S. Department of Agriculture, Food Safety Inspection Service has determined that six non-O157 Shiga toxin- producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) are adulterants in raw beef. Isolate and phenotypic discrimination of non-O157 STEC is problematic due to the lack of suitable agar media. The lack of distinct phenotypic color variation among non-O157serogroups cultured on chromogenic agar poses a challenge in selecting colonies for confirmation. In this study, visible and near-infrared hyperspectral imaging and chemometrics were used to detect and classify non-O157 STEC serogroups grown on Rainbow agar O157. The method was first developed by building spectral libraries for each serogroup obtained from ground-truth regions of interest representing the true identity of each pixel and thus each pure culture colony in the hyperspectral agar-plate image. The spectral library for the pure-culture non-O157 STEC consisted of 2,171 colonies, with spectra derived from 124,347 of pixels. The classification models for each serogroup were developed with a k nearest-neighbor classifier. The overall classification training accuracy at the colony level was 99%. The classifier was validated with ground beef enrichments artificially inoculated with 10, 50, and 100 CFU/ml STEC. The validation ground-truth regions of interest of the STEC target colonies consisted of 606 colonies, with 3,030 pixels of spectra. The overall classification accuracy was 98%. The average specificity of the method was 98% due to the low false-positive rate of 1.2%. The sensitivity ranged from 78 to 100% due to the false-negative rates of 22, 7, and 8% for O145, O45, and O26, respectively. This study showed the potential of visible and near-infrared hyperspectral imaging for detecting and classifying colonies of the six non-O157 STEC serogroups. The technique needs to be validated with bacterial cultures directly extracted from meat products and positive identification of colonies by using confirmatory tests such as latex agglutination tests or PCR. Copyright ©, International Association for Food Protection.


Yoon S.-C.,Quality and Safety Assessment Research Unit | Windham W.R.,Quality and Safety Assessment Research Unit | Ladely S.R.,Eastern Laboratory | Heitschmidt J.W.,Quality and Safety Assessment Research Unit | And 4 more authors.
Journal of Near Infrared Spectroscopy | Year: 2013

Direct plating on solid agar media has been widely used in microbiology laboratories for presumptive-positive pathogen detection, although it is often subjective and labour-intensive. Rainbow agar is a selective and differential chromogenic medium used to isolate pathogenic Escherichia coli (E. coli) strains. However, it is challenging to differentiate colonies of the six representative pathogenic non-O157 Shiga-toxin producing E. coli (STEC) serogroups (O26, O45, O103, O111, O121 and O145) on Rainbow agar due to the phenotypic differences and the presence of background microflora. Therefore, there is a need for a method or technology to objectively, rapidly and accurately perform high-throughput screening of non-O157 STEC colonies on agar plates. In this paper, we report the development of a visible-near infrared hyperspectral imaging technique and prediction model for differentiating colony types of the six non-O157 STEC serogroups in spread plates of pure cultures inoculated on Rainbow agar. The prediction model was based on supervised linear classification of factor scores obtained by principal component analysis (PCA). Both PCA-MD (Mahalanobis distance) and PCA-kNN (k-nearest neighbour) classifiers were used for model development. From the 24 hyperspectral images measured from two replicates, 51,173 spectral samples were collected from 1421 colonies. Chemometric preprocessing methods and other operating parameters, such as scatter correction, first derivative, moving average, sample size and number of principal components (PCs), were compared with a classification and regression tree (CART) method, configured as a classification tree and followed by brute-force searching from candidates selected by the CART. The number of PCs, scatter correction and moving average were selected as the most important elements to consider before selecting a set of candidate models. Cross-validation (CV), such as hold out and k-fold CV, was used to validate the prediction performance of candidate models. Serogroups O111 and O121 consistently showed over 99% classification accuracy regardless of the classification algorithms. However, the classification accuracies of serogroups O26, O45, O103 and O145 showed varying results from 84% up to 100%, depending on which preprocessing treatment and prediction model were adopted. The best overall mean classification accuracy of 95.06% was achieved with PCA-kNN (k = 3), six PCs, five-pixel sample size defined around each colony centre, standard normal variate and detrending, first derivative with 11-point gaps and moving average with 11-point gaps. Future studies will focus on automating colony segmentation, further improving detection accuracy of the developed models, expanding the spectral library to include background microflora from ground beef and developing prediction models to detect the target bacteria in the presence of background microflora. © IM Publications LLP 2013. All rights reserved.


PubMed | Quality and Safety Assessment Research Unit, Poultry Microbiological Safety and Processing Research Unit, Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. Department of Agriculture and University of Georgia
Type: Journal Article | Journal: Poultry science | Year: 2016

To estimate the potential for residual antimicrobial solution carryover, surface water accumulation and loss was measured on post-chill carcasses that were either dipped or sprayed with water. For all experiments, broilers were slaughtered, soft or hard scalded, defeathered, and eviscerated. Carcasses were immersion chilled, allowed to drip, and post-chill carcass weight (CW) recorded. For water dip treatment, carcasses were dipped for 0.5min in water and hung by a wing (n = 33) or a leg (n = 30) and CW recorded at 0, 0.5, 1, 2, and 5min post-dip. For water spray treatment, individual carcasses were hung by either the wings (n = 35) or legs (n = 34) from a shackle suspended from a scale. Water was sprayed at 80psi and post-spray CW recorded. Initial water accumulation (0min) for dipped carcasses was not significantly different (P > 0.05) for carcasses hung by the leg (101.0g) or wing (108.8g). Following the 5min drip time, 31g of water remained on the carcasses hung by the leg and only 10g on carcasses hung by the wing (P < 0.05). When carcasses were sprayed with water, initial water accumulation (0min) was 62g for carcasses hung by the legs and 60g for carcasses hung by the wings (P > 0.05). Following the 5min drip time, 1g or no water remained on the sprayed carcasses (P > 0.05). Carcasses that were dipped and hung by a leg for 5min retained significantly more water (31g) than carcasses that were dipped and hung by a wing (10g) or sprayed carcasses hung either way (0.3g) (P < 0.05). Post-chill water dip resulted in significantly higher initial carcass water accumulation than spraying (105g vs. 61g, P < 0.05). Carcass orientation during dripping only affected the amount of retained water for dipped carcasses. Dipped carcasses hung by a leg have the highest potential for residual carcass antimicrobial solution carryover and sprayed carcasses hung by either orientation have the lowest potential for residual antimicrobial solution carryover.


PubMed | Quality and Safety Assessment Research Unit
Type: Journal Article | Journal: Journal of food protection | Year: 2013

The U.S. Department of Agriculture, Food Safety Inspection Service has determined that six non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) are adulterants in raw beef. Isolate and phenotypic discrimination of non-O157 STEC is problematic due to the lack of suitable agar media. The lack of distinct phenotypic color variation among non-O157serogroups cultured on chromogenic agar poses a challenge in selecting colonies for confirmation. In this study, visible and near-infrared hyperspectral imaging and chemometrics were used to detect and classify non-O157 STEC serogroups grown on Rainbow agar O157. The method was first developed by building spectral libraries for each serogroup obtained from ground-truth regions of interest representing the true identity of each pixel and thus each pure culture colony in the hyperspectral agar-plate image. The spectral library for the pure-culture non-O157 STEC consisted of 2,171 colonies, with spectra derived from 124,347 of pixels. The classification models for each serogroup were developed with a k nearest-neighbor classifier. The overall classification training accuracy at the colony level was 99%. The classifier was validated with ground beef enrichments artificially inoculated with 10, 50, and 100 CFU/ml STEC. The validation ground-truth regions of interest of the STEC target colonies consisted of 606 colonies, with 3,030 pixels of spectra. The overall classification accuracy was 98%. The average specificity of the method was 98% due to the low false-positive rate of 1.2%. The sensitivity ranged from 78 to 100% due to the false-negative rates of 22, 7, and 8% for O145, O45, and O26, respectively. This study showed the potential of visible and near-infrared hyperspectral imaging for detecting and classifying colonies of the six non-O157 STEC serogroups. The technique needs to be validated with bacterial cultures directly extracted from meat products and positive identification of colonies by using confirmatory tests such as latex agglutination tests or PCR.


PubMed | Quality and Safety Assessment Research Unit and Nanjing Agricultural University
Type: | Journal: Food chemistry | Year: 2016

This study investigated the influence of partial substitution of NaCl with KCl on protein and lipid oxidation as well as antioxidant enzyme activities in dry-cured bacons during processing. The partial substitution was 0% KCl (I), 40% KCl (II), and 70% KCl (III). Compared with 0% KCl (I), the substitution of 40% NaCl with KCl did not significantly influence the protein and lipid oxidation and antioxidant enzyme activities. The bacons that were treated with 70% KCl treatment (III) showed increased lipid oxidation and antioxidant enzyme GSH-Px activity, whereas samples treated with formulas I and II showed higher protein oxidation and antioxidant enzyme catalase activity. These results demonstrate that the substitution of NaCl with KCl by more than 40% may significantly affect protein and lipid oxidation and that for the substitution of NaCl in further processed meat products with other chloride salts, salt content is very important for control of protein and lipid biochemical changes in finished products.

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