المؤلفون: WANG, HUA, FENG, HAO, LUO, YAGUANG

المصدر: Journal of Food Safety; Nov2006, Vol. 26 Issue 4, p335-347, 13p, 1 Black and White Photograph, 4 Charts, 2 Graphs

مصطلحات موضوعية: ESCHERICHIA coli O157:H7, ESCHERICHIA coli, ESCHERICHIA, MUSKMELON, CHLORINE

مستخلص: The effects of peroxyacetic acid (POAA), acidic electrolyzed water (AEW) and chlorine on inactivation of Escherichia coli O157:H7 on fresh-cut apples and cantaloupe rinds were investigated. Apple cylinders were dip-inoculated with E. coli O157:H7 and treated with sterilized water (control), chlorine, AEW or POAA for up to 8 min. Cantaloupe cylinders were spot-inoculated with E. coli O157:H7 to the rind and treated with sterilized water, AEW or POAA for up to 15 min. All sanitizer treatments showed a significantly (P < 0.05) higher inactivation than the control. The residual counts of E. coli O157:H7 on both fruits exhibited a dual-phasic reduction behavior, with a fast inactivation (D values: 0.8–5.0 min) in the first minute (phase I) of treatments followed by a much slower inactivation (D values: 14.6–59.8 min) in the remaining time (phase II). The dual-phasic inactivation seems to be related to fruit surface topography that determines the bacterial distribution. [ABSTRACT FROM AUTHOR]

: Copyright of Journal of Food Safety is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Vargas, Angela M., Kim, Moon S., Tao, Yang, Lefcourt, Alan M., Chen, Yud-Ren, LUO, Yaguang, SONG, Yoonseok, Buchanan, Robert

المصدر: Journal of Food Science (Wiley-Blackwell); Oct2005, Vol. 70 Issue 8, pe471-e476, 1p

مصطلحات موضوعية: FOOD contamination, FECAL contamination, MUSKMELON, FLUORIMETRY, FOOD chemistry

مستخلص: BSTRACT To determine whether detection of fecal contamination on cantaloupes is possible using fluorescence imaging, hyperspectral images of cantaloupes artificially contaminated with a range of diluted bovine feces were acquired from 425 to 774 nm in responses to ultraviolet-A (320 to 400 nm) excitation. Evaluation of images at emission peak wavelengths indicated that 675 nm exhibited the greatest contrast between feces contaminated and untreated surface areas. Two-band ratios compared with the single-band images enhanced the contrast between the feces contaminated spots and untreated cantaloupe surfaces. The 595/655-nm, 655/520-nm, and 555/655-nm ratio images provided relatively high detection rates ranging from 79% to 96% across all feces dilutions. However, both single band and ratio methods showed a number of false positives caused by such features as scarred tissues on cantaloupes. Principal component analysis (PCA) was performed using the entire hyperspectral images data; 2nd and 5th principal component (PC) image exhibited differential responses between feces spots and false positives. The combined use of the 2 PC images demonstrated the detection of feces spots (for example, minimum level of 16-μg/mL dry fecal matter) with minimal false positives. Based on the PC weighing coefficients, the dominant wavelengths were 465, 487, 531, 607, 643, and 688 nm. This research demonstrated the potential of multispectral-based fluorescence imaging for online applications for detection of fecal contamination on cantaloupes. [ABSTRACT FROM AUTHOR]

: Copyright of Journal of Food Science (Wiley-Blackwell) is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

المؤلفون: Redding, Marina¹ (AUTHOR), Zheng, Jie² (AUTHOR), Mowery, Joseph¹ (AUTHOR), Gu, Ganyu¹ (AUTHOR), Bolten, Samantha¹ (AUTHOR), Luo, Yaguang¹ (AUTHOR), Nou, Xiangwu¹ (AUTHOR) Xiangwu.nou@usda.gov

المصدر: Food Control. Apr2024, Vol. 158, pN.PAG-N.PAG. 1p.

مصطلحات موضوعية: *LISTERIA monocytogenes, *MUSKMELON, *BIOFILMS, *PLANT exudates, *TRANSCRIPTOMES

مستخلص: Plant exudate is likely the major nutrient source supporting the survival and biofilm formation of microorganisms in fresh produce processing environments. This study compared the impact of cantaloupe juice on the physiology and gene expression of Listeria monocytogenes (Lm) using microscopic and transcriptomic tools. Lm showed a strong autoaggregation and formed significantly more biofilms on stainless steel (SS) coupons when grown in cantaloupe juice in comparison to in TSB. SEM images revealed a different attachment profile of Lm on SS coupons. In TSB, Lm cells were mainly found in scratches and grooves of the metal surface, whereas, in cantaloupe juice they attached to the smooth surface as well. Lm planktonic and biofilm cells in cantaloupe juice exhibited stress-induced phenotypes, including strong cell elongation and increased proportion of cells with membrane permeability. Lm growth in cantaloupe juice resulted in distinct transcriptional profiles of both biofilm and planktonic cells in comparison to that in TSB. Functional annotation indicated that the significantly differentially expressed genes mainly participated in metabolism, signaling and stress response. Notably, certain pathways downregulated for planktonic cells were significantly upregulated for biofilm cells in cantaloupe juice compared to TSB, including ABC transporters, two-component system, quorum sensing, chemotaxis, and flagellar assembly. • L. monocytogenes (Lm) biofilm formation in cantaloupe juice was assessed by microscopic and transcriptomic analyses. • Lm growth in cantaloupe juice resulted in strong autoaggregation. • Lm biofilm formation in cantaloupe juice was greater than in laboratory medium TSB. • Lm growth and biofilm formation in cantaloupe juice resulted in global modulation in gene expression. [ABSTRACT FROM AUTHOR]

المؤلفون: Nyarko, Esmond¹ esmond.nyarko@ars.usda.gov, Kniel, Kalmia E.¹ kniel@udel.edu, Millner, Patricia D.² pat.millner@ars.usda.gov, Luo, Yaguang² yaguang.luo@ars.usda.gov, Handy, Eric T.² eric.handy@ars.usda.gov, Reynnells, Russell², East, Cheryl² cheryl.east@ars.usda.gov, Sharma, Manan² manan.sharma@ars.usda.gov

المصدر: International Journal of Food Microbiology. Oct2016, Vol. 234, p65-70. 6p.

مصطلحات موضوعية: *MUSKMELON, *LISTERIA monocytogenes, *MICROBIAL contamination, *FRUIT storage, *CYTOGENETICS, *ANALYSIS of variance

مستخلص: Whole cantaloupes ( Cucumis melo L.), marketed as ‘Rocky Ford’, were implicated in a large multi-state outbreak of listeriosis in the United States in 2011; however, survival and growth of Listeria monocytogenes on whole cantaloupes remains relatively unexplored. The research presented here evaluated three different storage temperatures, two sites of contamination of cantaloupes, and two cantaloupe varieties to determine their effect on the survival of L. monocytogenes . ‘Athena’ and ‘Rocky Ford’ cantaloupe cultivars were grown in soil and harvested, and individual melons subsequently received a multi-strain inoculum of L. monocytogenes (6 log CFU/melon), which were then stored at 4 °C, 10 °C, and 25 °C. Changes in L. monocytogenes populations on the rinds and stem scars of cantaloupes stored at each temperature were determined at selected times for up to 15 days. An analysis of variance revealed that inoculation site and storage temperature significantly affected survival of L. monocytogenes on cantaloupes during storage ( p < 0.05), but cultivar did not influence L. monocytogenes ( p > 0.05). Populations of L. monocytogenes on stem scars of cantaloupes stored at 25 °C increased by 1–2 log CFU/melon on day 1, and were significantly greater than those on cantaloupes stored at 4 °C or 10 °C ( p < 0.05), which remained constant or increased by approximately 0.3 log CFU/melon, respectively, over the same time period. A decrease of 2–5 log CFU/melon of L. monocytogenes occurred on the rinds of cantaloupes during storage by day 7, and were not significantly different at the three different storage temperatures ( p > 0.05). In trials performed in rind juice extracts, populations of L. monocytogenes decreased by 3 log CFU/mL when stored at 25 °C by day 3, but grew by 3–4 log CFU/mL when stored at 4 °C over 7 days. Overall, site of contamination and storage temperature influenced the survival of L. monocytogenes on cantaloupes more than cantaloupe cultivar type. [ABSTRACT FROM AUTHOR]

المؤلفون: Gu, Ganyu¹ (AUTHOR), Kroft, Brenda² (AUTHOR), Lichtenwald, Marina¹ (AUTHOR), Luo, Yaguang¹ (AUTHOR), Millner, Patricia¹ (AUTHOR), Patel, Jitendra¹ (AUTHOR), Nou, Xiangwu¹ (AUTHOR) xiangwu.nou@ars.usda.gov

المصدر: International Journal of Food Microbiology. Mar2022, Vol. 364, pN.PAG-N.PAG. 1p.

مصطلحات موضوعية: *LISTERIA monocytogenes, *REFRIGERATED storage, *LETTUCE, *MUSKMELON, *NUCLEOTIDE sequencing, *MICROBIAL diversity, *BACTERIAL communities

مستخلص: Listeria monocytogenes (Lm) outbreaks and recalls associated with fresh produce in recent years have heightened concerns and demands from industry and consumers to more effectively mitigate the contamination risk of this foodborne pathogen on fresh produce. In this study, the growth of Lm and indigenous bacteria on fresh-cut cantaloupe and romaine lettuce held at refrigerated (4 °C) and abusive (10–24 °C) temperatures was determined by both culture dependent and independent methods. Composition and dynamics of bacterial communities on Lm inoculated and non-inoculated samples were analyzed by 16S rRNA high-throughput sequencing. Fresh-cut cantaloupe provided favorable growth conditions for Lm proliferation (1.7 and >6 log increase at refrigerated and abusive temperatures, respectively) to overtake indigenous bacteria. The Lm population also increased on fresh-cut lettuce, but the growth rate was lower than that of the total mesophilic bacteria, resulting in 0.4 and >2 log increase at refrigerated and abusive temperatures. Microbial diversity of fresh-cut cantaloupe was significantly lower than that of fresh-cut romaine lettuce. The Shannon index of microbial communities on cantaloupe declined after storage, but it was not significantly changed on lettuce samples. Shifts in the bacterial microbiome on cantaloupe were mainly affected by Lm inoculation, while both inoculation and storage temperature played significant roles on lettuce bacterial communities. Multiple indigenous bacteria, including Leuconostoc and Weissella spp., were negatively correlated to Lm abundance on romaine lettuce, and were determined by bioassay as potential anti-listerial species. Data derived from this study contribute to better understanding of the relationship between Lm and indigenous microbiota on fresh-cut produce during storage. • Assessed microbiome shifts on fresh-cut cantaloupe and romaine lettuce during storage. • Determined Listeria monocytogenes interactions with fresh-cut cantaloupe and romaine lettuce bacteria • Observed L. monocytogenes growth as impacted by the complexity of fresh-cut produce microbiome • Isolated and identified multiple L. monocytogenes antagonist strains. [ABSTRACT FROM AUTHOR]