Hurdle Effect of Hot Air Impingement Drying and Surfactant-Sanitizer Wash on Removal of Listeria innocua from Fresh Apples

2020 ◽  
Vol 83 (9) ◽  
pp. 1488-1494 ◽  
Author(s):  
EWA PIETRYSIAK ◽  
JULIANNE M. KUMMER ◽  
INES HANRAHAN ◽  
GIRISH M. GANJYAL
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Evaporation Rate ◽  
Sodium Dodecyl ◽  
Listeria Innocua ◽  
Tween 20 ◽  
Log Reduction ◽  
Hot Air ◽  
Lauric Arginate ◽  
Dodecyl Sulfate ◽  
Air Impingement

ABSTRACT This study investigated the decontamination efficacy of washing treatments for whole fresh apples by using washes containing surfactants, lauric arginate, sodium dodecyl sulfate, and Tween 20, combined with peracetic acid (PAA), followed by hot air impingement drying. Whole fresh apples of selected varieties (Gala and Granny Smith) were inoculated with Listeria innocua (7 log CFU/mL) by using a dipping method, and then dried and subjected to wash treatments with selected washing solutions (H2O, PAA, PAA–lauric arginate, PAA–sodium dodecyl sulfate, and PAA–Tween 20), followed by hot air impingement drying at two different temperature and time conditions, 93°C for 60 s or 121°C for 25 s. The H2O and PAA wash followed by hot air impingement drying led to a maximum 1.5-log reduction of L. innocua on the fruit surface. Adding surfactants increased the effectiveness of washing and drying treatments, resulting in an approximate 2.2-log reduction. Surfactants increased the spreadability and evaporation rate of the washing solutions. Posttreatment changes in apple firmness were assessed during a 21-day storage at 4 and 21°C. The hot air impingement drying had no adverse effect on the firmness of the apples and did not show any further reduction in L. innocua. Washing apples with solutions containing surfactants combined with PAA followed by hot air impingement drying helped to reduce the microbial loads to some extent and may help to reduce drying times significantly. HIGHLIGHTS

Optimization of DNA Extraction and Molecular Detection of Cryptosporidium Oocysts in Natural Mineral Water Sources

2004 ◽  
Vol 67 (3) ◽  
pp. 524-532 ◽  
Author(s):  
ROSELY A. B. NICHOLS ◽  
HUW V. SMITH
Keyword(s):  
Public Health ◽  
Sodium Dodecyl Sulfate ◽  
Dna Extraction ◽  
Mineral Water ◽  
Sodium Dodecyl ◽  
Mineral Waters ◽  
Tween 20 ◽  
Cryptosporidium Oocysts ◽  
Dodecyl Sulfate ◽  
Lysis Buffer

The numerous published methods for extracting DNA from Cryptosporidium oocysts for PCR identify the lack of an optimized standard method for clinical, environmental, and public health investigations of cryptosporidiosis. A method that maximizes DNA extraction reliably, particularly from small numbers of partially purified or purified oocysts present in mineral waters and environmental samples, is required. We describe a maximized method for liberating DNA from Cryptosporidium parvum oocysts by 15 cycles of freezing (liquid nitrogen) and thawing (65°C) in lysis buffer containing sodium dodecyl sulfate. The inhibitory effects of sodium dodecyl sulfate are abrogated by the addition of Tween 20 to the PCR reaction. We tested seven different C. parvum oocyst isolates, consistently detecting fewer than five oocysts following direct PCR amplification of a segment of the 18S rRNA gene. Older oocysts, which were more refractory to freeze-thawing, were disrupted effectively. A single oocyst in each of two mineral water concentrates was detected by both microscopy and PCR/Southern blotting. We recommend 15 cycles of freeze-thawing, with thawing at 65°C in lysis buffer, to maximize oocyst disruption and DNA extraction, particularly when isolate history and oocyst age are unknown. Both the DNA extraction method and the PCR described can be used for clinical, environmental, and public health investigations of cryptosporidiosis.

Evaluation of Levulinic Acid and Sodium Dodecyl Sulfate as a Sanitizer for Use in Processing Georgia-Grown Cantaloupes

2013 ◽  
Vol 76 (10) ◽  
pp. 1767-1772 ◽  
Author(s):  
CATHY C. WEBB ◽  
LINDSEY E. DAVEY ◽  
MARILYN C. ERICKSON ◽  
MICHAEL P. DOYLE
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Cucumis Melo ◽  
Levulinic Acid ◽  
Sodium Dodecyl ◽  
Scar Tissue ◽  
Log Reduction ◽  
Treatment Tank ◽  
Dodecyl Sulfate ◽  
Processing Line ◽  
Cucumis Melo L

Freshly harvested Georgia-grown cantaloupes (Cucumis melo L. var. reticulatus cv. Athena and Atlantis) were spot inoculated with 100 μl of a five-strain mixture of Salmonella enterica serovar Poona (9 log CFU/ml) at the stem scar and on the netted rind and then subjected to no treatment (control) or a 6-min treatment (tank only) in water, 120 ppm of chlorine (pH 7.0), 1% levulinic acid plus 0.1% sodium dodecyl sulfate (SDS; pH 3.0), or 2% levulinic acid plus 0.2% SDS (pH 3.0). The log reduction for the tank-only treatments was 0.31, 0.59, 1.32, and 1.37 log CFU/g at the stem scar and 0.97, 1.59, 2.06. and 3.37 log CFU/g on the netted rind for water, chlorine, 1% levulinic acid plus 0.1% SDS, and 2% levulinic acid plus 0.2% SDS, respectively. A greater log reduction was observed for the cantaloupe surface tissue with the water, chlorine, and 2% levulinic acid plus 0.2% SDS treatments when additional sanitizer (2 ml) and brushing (to simulate cantaloupes tumbling over brushes on the processing line) were added to the dump tank treatment. The stem scar tissue reductions were 0.90, 1.69, and 1.53 log CFU/g, whereas the netted rind reductions were 1.56, 2.50, and 4.47 log CFU/g after treatment with water, chlorine, and 2% levulinic acid plus 0.2% SDS, respectively. These data suggest that 2% levulinic acid plus 0.2% SDS is effective for reducing Salmonella on the netted rind surface of cantaloupes. However, neither 2% levulinic acid plus 0.2% SDS nor 120 ppm of chlorine substantially reduced Salmonella on stem scar tissue.

Quantitative Analysis of Dye Decolourization Reactions in Mixed Micellar Systems of Sodium Dodecyl Sulfate with Tween-20, Tween-80, and Triton X-100

2012 ◽  
Vol 65 (2) ◽  
pp. 153 ◽  
Author(s):  
Kimkholhing Lunkim ◽  
M. Niraj Luwang ◽  
Sri K. Srivastava
Keyword(s):  
Quantitative Analysis ◽  
Sodium Dodecyl Sulfate ◽  
Sodium Dodecyl ◽  
Tween 80 ◽  
Inhibitory Effect ◽  
Reaction Rate Constant ◽  
Tween 20 ◽  
Sds Micelles ◽  
Hydroxyl Ion ◽  
Dodecyl Sulfate

The reaction of triphenylmethane dye (ethyl violet) with hydroxyl ion has been investigated in absence and presence of micelles. In micellar solutions, the solubilization of dye carbocation is observed. The reaction rate constant follows pseudo-first order kinetics with respect to the nucleophile. In presence of sodium dodecyl sulfate (SDS) micelles, an inhibitory effect is observed due to repulsion of the nucleophile to the strongly bound dye carbocation in the negatively charged SDS aggregate. The presence of nonionic surfactant reduces the inhibitory effect of the anionic SDS micelles. Quantitative analysis of the micellar data obtained has been done by applying a positive cooperativity model of enzyme catalysis. The value of n (index of cooperativity) has been found to be greater than 1 for all systems under study. The presence of solvents such as ethanol, n-propanol, and n-butanol reduces the inhibitory effect of the micelles.

scholarly journals Conductometric study of sodium dodecyl sulfate - nonionic surfactant (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) mixed micelles in aqueous solution

2012 ◽  
Vol 66 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Dejan Cirin ◽  
Mihalj Posa ◽  
Veljko Krstonosic ◽  
Maja Milanovic
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Synergistic Effect ◽  
Nonionic Surfactants ◽  
Mixed Micelles ◽  
Sodium Dodecyl ◽  
Tween 80 ◽  
Tween 20 ◽  
Dodecyl Sulfate ◽  
Tween 60 ◽  
Triton X

The present study is concerned with the determination of the critical micelle concentration (cmc) of mixed micelles of sodium dodecyl sulfate with one of five nonionic surfactants (Triton X-100, Tween 20, Tween 60, Tween 80 or Tween 85) from conductance measurements. Based on the calculated values of the ? parameters we have noticed that SDS-nonionic surfactants mostly showed strong synergistic effect. It was found that nonionic surfactants with mainly longer and more hydrophobic tail show stronger interactions with hydrophobic part of SDS, thus expressing stronger synergism. In SDS-Tween 80 binary system the strongest synergistic effect was noticed. SDS-Tween 85 micellar system showed antagonistic effect, most probably because the presence of the double bond in its three hydrophobic tails (three C18 tails) makes it sterically rigid.

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