Effects of natural antimicrobials on prevention and reduction of bacterial cross-contamination during the washing of ready-to-eat fresh-cut lettuce

2017 ◽  
Vol 23 (5) ◽  
pp. 403-414 ◽  
Author(s):  
Cristina Pablos ◽  
Alba Fernández ◽  
Alison Thackeray ◽  
Javier Marugán
Keyword(s):  
Antimicrobial Properties ◽  
Complete Removal ◽  
Wash Water ◽  
Plate Count ◽  
Salmonella Spp ◽  
Natural Antimicrobials ◽  
Benzyl Isothiocyanate ◽  
Standard Plate Count ◽  
Washing Process ◽  
Fresh Cut

Microbiological safety of the fresh-cut produce may not be guaranteed if the quality of wash water is not maintained. The use of natural antimicrobials as alternative to chlorine may offer interesting possibilities for disinfecting wash water. Antimicrobial properties of allyl- and benzyl-isothiocyanates, respectively, and chitosan against Salmonella spp. were evaluated by standard plate count. Minimal inhibitory concentration values were observed for benzyl-isothiocyanate and chitosan, corresponding to 50 and 1000 mgl−1, respectively. A 5 min washing of 25 g fresh-cut lettuce was performed. Transfer of Salmonella from the water to the produce was observed. Benzyl-isothiocyanate addition of 75 mgl−1 before starting the washing process gave rise to a complete removal of total bacteria and Salmonella in the wash water after 24 h before starting the second cycle. Antimicrobial benzyl-isothiocyanate effects have been demonstrated to persist after 48 h.

scholarly journals Physicochemical Quality and Chemical Safety of Chlorine as a Reconditioning Agent and Wash Water Disinfectant for Fresh-Cut Lettuce Washing

2013 ◽  
Vol 79 (9) ◽  
pp. 2850-2861 ◽  
Author(s):  
Sam Van Haute ◽  
Imca Sampers ◽  
Kevin Holvoet ◽  
Mieke Uyttendaele
Keyword(s):  
Escherichia Coli ◽  
Water Contamination ◽  
Tap Water ◽  
Water Disinfection ◽  
Wash Water ◽  
Chemical Safety ◽  
Residual Concentration ◽  
Content Type ◽  
Washing Process ◽  
Fresh Cut

ABSTRACTChlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated withEscherichia coliO157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The model that incorporated chlorine dose and chemical oxygen demand (COD) of the wash water accurately predicted inactivation.Listeria monocytogeneswas more resistant to chlorine reconditioning in artificial wash water thanSalmonellaspp. andEscherichia coliO157. During the washing process with inoculated lettuce (4 log CFU/g), in the absence of chlorine, there was a rapid microbial buildup in the water that accumulated to 5.4 ± 0.4 log CFU/100 ml after 1 h. When maintaining a residual concentration of 1 mg/liter free chlorine, wash water contamination was maintained below 2.7, 2.5, and 2.5 log CFU/100 ml for tap water and artificial process water with COD values of 500 and 1,000 mg O2/liter, respectively. A model was developed to predict water contamination during the dynamic washing process. Only minor amounts of total trihalomethanes were formed in the water during reconditioning. Total trihalomethanes accumulated to larger amounts in the water during the wash water disinfection experiments and reached 124.5 ± 13.4 μg/liter after 1 h of execution of the washing process in water with a COD of 1,000 mg O2/liter. However, no total trihalomethanes were found on the fresh-cut lettuce after rinsing.

Modelling the combined effect of chlorine, benzyl isothiocyanate, exposure time and cut size on the reduction of Salmonella in fresh-cut lettuce during washing process

2020 ◽  
Vol 86 ◽  
pp. 103346 ◽  
Author(s):  
Sofia Griselda Cuggino ◽  
Isabel Bascón-Villegas ◽  
Francisco Rincón ◽  
Maria Alejandra Pérez ◽  
Guiomar Posada-Izquierdo ◽  
...  
Keyword(s):  
Exposure Time ◽  
Combined Effect ◽  
Benzyl Isothiocyanate ◽  
Washing Process ◽  
Fresh Cut ◽  
Effect Of Chlorine

Assessment of the Microbiological Quality of Spices and Herbs

1986 ◽  
Vol 49 (12) ◽  
pp. 958-963 ◽  
Author(s):  
JOSEPHINE PAFUMI
Keyword(s):  
Substantial Reduction ◽  
Microbiological Quality ◽  
Health Concern ◽  
Plate Count ◽  
Toxicity Tests ◽  
Mustard Seed ◽  
Salmonella Spp ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Mold Count

This investigation of the mirobiology of spices and herbs has resulted in the isolaton of pathogenic, potentially pathogenic and spoilage organisms. Tests undertaken included Standard Plate Count (SPC), Yeast and Mold Count, counts for Escherichia coli, coliforms, Bacillus cereus, presumptive Clostridium perfringens; and the presence of Salmonella. The SPC ranged from less than 1.0 × 102 cfu/g in cloves and cayenne pepper to 2.0 × 108 cfu/g in black peppercorns. Most other spices and herbs averaged a total microbial load of about 1.0 × 105 cfu/g. Cloves and cayenne were the only spices found to be free of B. cereus, C. perfringens, coliforms, E. coli, and Salmonella spp.; and low in mold count. In contrast, peppercorns consistently had the highest level of microbial contamination, containing high levels of all organisms tested. Sporeformers and coliforms were detected in most other spices and herbs; B. cereus at a load ranging from less than 1.0 × 102 cfu/g to 1.0 × 105 cfu/g, with most being less than 1.0 × 103 cfu/g (except for cinnamon and broken mace which yielded higher counts); presumptive C. perfringens counts were usually <1.0 × 102 cfu/g (except for mixed herbs and ground paprika); and coliforms at <10/g (except for ground paprika which yielded higher counts). Salmonella was isolated from black peppercorns, white peppercorns and fenugreek seed at a relatively high incidence level (8.2, 1.5, 7.1%, respectively). Fumigation with ethylene oxide proved effective; resulting in Salmonella-free spices and substantial reduction (>90%) in the overall organism count. The spice toxicity tests in regard to Salmonella demonstrated that diluted spice:pre-enrichment ratios of 1:1000 are necessary for cloves, pimento, cinnamon, oregano and mustard seed to confidently isolate this organism of public health concern.

Pyruvate as an Indicator of Quality in Grading Nonfat Dry Milk1

1982 ◽  
Vol 45 (6) ◽  
pp. 561-565 ◽  
Author(s):  
R. T. MARSHALL ◽  
Y. H. LEE ◽  
B. L. O'BRIEN ◽  
W. A. MOATS
Keyword(s):  
Geometric Mean ◽  
Regression Line ◽  
Skim Milk ◽  
Plate Count ◽  
Department Of Agriculture ◽  
Standard Plate Count ◽  
Geometric Average ◽  
Dry Milk ◽  
Standard Plate ◽  
Microscopic Count

Samples of skim milk and nonfat dry milk (NDM) made from it were collected, paired and tested for pyruvate concentration, [P], and Direct Microscopic count (DMC). The skim milk was tested for Standard Plate Count (SPC) and Psychrotrophic Plate Count (PPC). The geometric average DMC of skim milk was more than three times higher than that of the paired NDM samples. However, [P] of NDM was not significantly different from that of the skim milk. Although [P] of skim milk was poorly correlated with SPC and PPC, r = .31 and .26, respectively, it was relatively well correlated with DMC, r = .64. Data were widely dispersed around the regression line when [P] was ≤ 4.0 mg/L. However, [P] increased rapidly when DMCs were > 106/ml. A limit of 10 mg/L of [P] in NDM reconstituted 1:9 was chosen to represent the current U.S. Department of Agriculture Standard for DMC in NDM. This limit failed to classify about 10% of the samples correctly, assuming that each geometric mean DMC was correct. However, the probability that samples meeting the DMC standard would be rejected by the pyruvate test was quite low and the probability was moderate that samples which would be acceptable by the pyruvate test would be rejected by the DMC. For the latter, 28% of the samples having DMCs of ≥ 107/ml contained < 10 mg/L of pyruvate. No sample having ≥ 10 mg/L of pyruvate had a DMC of ≤ 107/ml. Pyruvate concentration in NDM did not change during storage at 5 or 32°C for 90 days.

Bioluminescence: A Rapid Indicator of Escherichia Coli O157:H7 in Selected Yogurt and Cheese Varieties

1997 ◽  
Vol 60 (8) ◽  
pp. 891-897 ◽  
Author(s):  
L. M. HUDSON ◽  
J. CHEN ◽  
A. R. HILL ◽  
M. W. GRIFFITHS
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Cottage Cheese ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Potential Hazard ◽  
Growth And Survival ◽  
E Coli ◽  
Standard Plate Count ◽  
Standard Plate

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 have been commonly associated with products derived from ground beef, but recently the organism has been implicated as the causative agent in outbreaks involving yogurt and cheese. This finding has raised concern about the potential for its growth and survival in fermented dairy products. A bioluminescent strain of E. coli O157:H7 was used to determine postprocessing survival in yogurt with live cultures at pH 4.17, 4.39, and 4.47 stored at 4 and 10°C. In addition, survival of E. coli O157:H7 was monitored during the manufacture of Cottage, Colby, Romano, and Feta cheeses. Results indicated survival for 8 and 5 days at 4 and 10°C respectively in yogurt at pH 4.17, 17 and 15 days at 4 and 10°C respectively in yogurt at pH 4.39, and 17days at both 4 and 10°C in yogurt at pH 4.47. E. coli O157:H7 did not survive cooking procedures at 56°C in Cottage cheese. However, the pathogen survived for 27, 30, and 27 days in Colby, Romano, and Feta cheeses respectively. A high correlation of r2 > 0.89 was obtained between counts of bioluminescenct colonies and standard plate count for all yogurt and cheese varieties, indicating that bioluminescence was a sensitive and rapid indicator of cellular viability for E. coli O157:H7. Survival of the pathogen, as indicated by this method, is possible in highly acidic environments even at refrigeration temperatures. This poses a potential hazard should postprocessing contamination occur.

Evaluation of the 3M Dry Medium Culture Plate (Petrifilm™ SM) Method for Determining Numbers of Bacteria in Raw Milk1

1984 ◽  
Vol 47 (10) ◽  
pp. 753-755 ◽  
Author(s):  
R. E. GINN ◽  
V. S. PACKARD ◽  
T. L. FOX
Keyword(s):  
Cold Water ◽  
Correlation Coefficients ◽  
Raw Milk ◽  
Water Soluble ◽  
Gelling Agent ◽  
Plate Count ◽  
Suitable Alternative ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Indicator Dye

The 3M Company has developed a sample-ready system (Petrifilm ™ SM) for enumerating bacteria in milk and other food products. The testing unit consists of Standard Methods culture medium coated onto a base film and overlaid with a second film coated with a cold-water-soluble gelling agent and tetrazolium indicator dye. As such, the system is ready to accept samples of product. A pipette or 0.001-ml plate loop continuous pipetting syringe can be used for applying samples. In this study, both methods of sample addition were used and results compared with those of the Standard Plate Count (SPC) and standard Plate Loop (PL) methods for determining bacteria numbers in raw milk. In total, 108 samples were analyzed in duplicate by each of the four methods. The correlation coefficients (r) between the 3M-SPC and SPC, 3M-PL and PL, 3M-PL and SPC and PL and SPC were 0.946, 0.935, 0.941, and 0.974, respectively. Repeatability, as measured by mean log10 variance for duplicate determinations, was essentially the same for the four methods, and in all instances less than 0.005. The mean log10 differences between the SPC and 3M-SPC, and SPC and 3M-PL were, respectively, −0.177 and −0.168. The preceding statistical criteria suggest the Petrifilm™ SM method to be a suitable alternative to the SPC or the PL procedure.

scholarly journals The Survey of Microbial Quality of the Dry Sample, Extract and Brewing of some Medicinal Plants

2014 ◽  
Vol 6 (4) ◽  
pp. 478-482
Author(s):  
Razieh VALIASILL ◽  
Majid AZIZI ◽  
Maasome BAHREINI ◽  
Hossein AROUIE
Keyword(s):  
Medicinal Plants ◽  
Pathogenic Bacteria ◽  
Agar Medium ◽  
Total Count ◽  
Plate Count ◽  
Microbial Quality ◽  
Salmonella Spp ◽  
E Coli ◽  
Wide Range

Medicinal plants may be exposed to a wide range of microbial contamination during pre- and post- harvest stages and they can present high microbial counts. In this study, the microbial quality of 44 samples of dry herbs namely: mint (Menthaspp.), lemon balm (Melissa officinalis), summer savory (Satureja hortensis), zataria (Zataria multiflora), Indian valerian (Valeriana wallichii), their brewing and extracts were analyzed. Total count using plate count agar medium (PCA), coliform count by Violet Red Bile Agar (VRBL), Enterobacteriacea by Violet Red Bile Glucose (VRBG) were evaluated. Medium Baird-Parker agar (BP) medium and Tryptone Bile X-Gluc (TBX) medium were used for the isolation and enumeration of Staphylococcus aurous and E. coli spp. respectively. Furthermore, Xylose Lysine Deoxycholate agar medium (XLD) and Bismuth Sulfite Agar medium(BSA) were used for detection of Salmonella spp. Fungal and mold contamination was assessed using yeast extract glucose chloramphenicol agar. The results showed that the contamination of the samples with total count (100%) and Enterobacteriaceae (85%), total coliform (83%), mold and yeast (98%) and E. coli ssp. (2.27) were detected, including in the study samples the absence of pathogenic bacteria like Staphylococcus aurous, Salmonella spp. Moreover, the extract had a lower microbial load in comparison to dry herb samples. Also, the lowest and the highest of contamination rates were observed for Indian valerian and zataria, respectively. According to the results, there is a need to control the environmental conditions and improve hygiene in the production process; even more, it is recommended to choose a suitable decontamination method for disinfection during packing medicinal plants and during post-packing manipulation and transport.

scholarly journals Comparison of Probiotic Isolate Growth in Natural Culture with Various Carbon Sources

2021 ◽  
Vol 6 (2) ◽  
pp. 103-107
Author(s):  
Sitti Nur Ilmiah ◽  
Zaraswati Dwyana ◽  
Asadi Abdullah
Keyword(s):  
Carbon Sources ◽  
Plate Count ◽  
Standard Plate Count ◽  
Standard Plate

Probiotik merupakan mikroba hidup yang memberikan pengaruh menguntungkan pada inang karena dapat menyeimbangkan mikroba yang ada dalam saluran pencernaan menjadi meningkat. Pemanfaatan tersebut dapat memberikan pengaruh positif dan kesehatan bagi inang sehingga sangat baik untuk diaplikasikan. Pemanfaatan bahan alami dapat menekan biaya media tumbuh sehingga perlu penggantian media sintetik dengan media alami karena memiliki harga yang relatif lebih murah tetapi mengandung nutrien penting bagi pertumbuhan mikroba. Tujuan penelitian ini adalah untuk mengetahui pertumbuhan isolat probiotik berdasarkan lama waktu kutur dalam media alami yang mengandung sumber karbon berbeda. Pertumbuhan isolat probiotik dalam berbagai sumber karbon dilakukan melalui metode Standard Plate Count (SPC). Melalui metode SPC didapatkan jumlah koloni isolat G dari masing-masing media berupa kanji, sagu, dan dedak yaitu 2,3 x 108 Cfu/mL, 6,4 x 106 Cfu/mL, dan 4,3 x 106 Cfu/mL selama 48 jam; 2,6 x 108 Cfu/mL, 1,6 x 108 Cfu/mL, dan 1,0 x 108 Cfu/mL selama 96 jam; 4,6 x 108 Cfu/mL, 1,8 x 108 Cfu/mL, dan 1,2 x 108 Cfu/mL selama 144 jam. Hasil yang didapatkan menunjukkan bahwa isolat G mampu ditumbuhkan dalam media alami berupa kanji, sagu dan dedak.

Microbiological Quality of Shellfish-Growing Waters in Chesapeake Bay

1994 ◽  
Vol 57 (3) ◽  
pp. 229-234 ◽  
Author(s):  
TUU-JYI CHAI ◽  
TZYY-JAN HAN ◽  
RALPH R. COCKEY
Keyword(s):  
Escherichia Coli ◽  
Chesapeake Bay ◽  
Water Samples ◽  
Microbiological Quality ◽  
Geographic Area ◽  
Water Area ◽  
Fecal Coliforms ◽  
Plate Count ◽  
Standard Plate Count ◽  
Standard Plate

A total of 338 water samples were collected at 20 stations from three geographically shellfish-growing areas in Chesapeake Bay from May to September 1989. Samples were examined for standard plate count, total coliforms, fecal coliforms, Escherichia coli and coliphages. Salinity, dissolved oxygen and temperature varied slightly with the depth, season, and geographic area of water samples. The geometric means of standard plate count for the three areas were 135, 355 and 275/ml, respectively. The range of means of fecal coliform for these areas was from <3 to 93/100 mi. Escherichia coli counts were also low with a range of <3 to 93/100 mi and a mean of < 3/100 mi. The growing water area adjacent to cropland was found to have higher bacterial counts than those of the other two areas. Levels of male-specific phages were very low. Results indicate that shellfish-growing waters in all three areas were of satisfactory bacteriological quality.

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