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EVALUATION OF CITREX® ACTIVITY VS. A CHLORINE
SOLUTION AS A DISINFECTANT DURING RAW SHRIMP PACKING
PROCESS
PROCEDURE
• Samples were collected using the following protocol:• Product must be prepared using potable water, in agreement
with the recommended dose rate:• 2 milliliters per liter of solution for a 400 ppm final
concentration. Concentrated product solution was 200,000 ppm (20%).
• A fresh working solution must be prepared on the day of use, even though the molecule is stable, and preparation on the previous day does not decrease product’s microbicidal potency.
• 1.- Technical shrimp processing steps were performed.• 2.- A 400 ppm Lonlife solution is used for final rinsing. This
solution is not rinsed, but allowed to act on shrimp.• 3.- Proceed with packing and freezing processes.
• These assays were performed using a 200 ppm dyed Lonlife, solution, consistent with company’s regular practices, and without the previous use of any disinfectants.
• Assays were carried out on both white shrimp (sea catch) and farm-harvested shrimp.
• Assays were performed during different working shifts. A total of 3 assays were performed per product (i.e. 3 assays for sea shrimp and 3 for farm shrimp).
DETERMINATION OF PRODUCT-ESCORT HETEROTROPHIC BIOMASS
• Total mesophyllic microflora count was determined using PCA agar and deep seeding.
• The first 1:100 dilution was obtained as follows: A 10-g shrimp sample was macerated using a sterilized mortar then diluted in 90 ml sterile 1% peptone water.
• Afterwards, 1:100 serial dilutions were prepared by adding 1 ml of the first solution to the next, until a 105 dilution was obtained.
• Preparation was then seeded by pipetting 1 ml of the mix to the bottom of a Petri dish. 20 ml PCA agar were added then incubated for 24 - 48 hours at 35°C. After this time results were read.
• During January 2006 the first 12 samples were received. All 12 samples were processed in duplicate.
Assay 1 Assay 2
Sample Mesophylls Sample Mesophylls
Sample 1 3,000 Sample 1 400
Sample 2 4,000 Sample 2 4,000
Sample 3 1,800 Sample 3 3,000
400 ppm Citrex
Assay 1 Assay 2
Sample Mesophylls Sample Mesophylls
Sample 1 7,800 Sample 1 11,000
Sample 2 12,000 Sample 2 4,500
Sample 3 16,000 Sample 3 7,000
200 ppm Chlorine
Farm shrimp 400 ppm Citrex
Assay 1 Assay 2
Sample Mesophylls Sample Mesophylls
Sample 1 520 Sample 1 280
Sample 2 310 Sample 2 1,500
Sample 3 5,400 Sample 3 1,100
Sample 4 2,700 Sample 4 950
Assay 1 Assay 2
Sample Mesophylls Sample Mesophylls
Sample 1 3,500 Sample 1 1,500
Sample 2 4,700 Sample 2 2,600
Sample 3 1,900 Sample 3 2,200
Sample 4 3,300 Sample 4 1,100
200 ppm Chlorine
COLIMETRIC DETERMINATION TO ASSESS PRODUCT SANITARY SATUS POSTDISINFECTION
• Coliforms and E. coli were quantified by colimetric analysis. For this purpose the most probable number (MPN) technique was applied, using Brilla medium.
Coliforms - 400 ppm CitrexAssay 1 Assay 2
Sample Coliforms E. coli Sample Coliforms E. coli
Sample 1 90 4 Sample 1 90 4
Sample 2 23 4 Sample 2 23 4
Sample 3 4 < 3 Sample 3 4 < 3
200 ppm Chlorine
Assay 1 Assay 2
Sample Coliforms E. coli Sample Sample E. coli
Sample 1 200 21 Sample 1 200 9
Sample 2 200 3 Sample 2 200 3
Sample 3 200 40 Sample 3 200 9
Coliform Assays:Only farm shrimp, 400 ppm Citrex (March)
Assay 1 Assay 2
Sample Coliforms E. coli Sample Coliforms E. coli
Sample 1 11 < 3 Sample 1 9 < 3
Sample 2 7 <3 Sample 2 4 <3
Sample 3 3 < 3 Sample 3 11 3
Sample 4 21 3 Sample 4 9 3
Farm Shrimp - 200 ppm Chlorine
Assay 1 Assay 2
Sample Coliforms E. coli Sample Coliforms E. coli
Sample 1 11 <3 Sample 1 9 4
Sample 2 70 7 Sample 2 15 3
Sample 3 9 3 Sample 3 <3 <3
Sample 4 21 <3 Sample 4 23 11
GENUS DETERMINATIONGENUS DETERMINATIONSalmonella Salmonella spp. spp.
Salmonella spp. Research400 ppm Citrex
Assay 1 Assay 2
Sample Salmonella spp. Sample Salmonella spp.
Sample 1 Negative Sample 1 Negative
Sample 2 Negative Sample 2 Negative
Sample 3 Negative Sample 3 Negative
Sea shrimp - Salmonella 200 ppm chlorine
Assay 1 Assay 2 ID
Sample Salmonella spp.
Sample Salmonella spp.
Sample 1 POSITIVE Sample 1 POSITIVE Salmonella enteritidis
Sample 2 POSITIVE Sample 2 POSITIVE Salmonella enteritidis
Sample 3 Negative Sample 3 Negative
VIBRIO GENUS RESEARCH
• The genus Vibrio was studied on the samples submitted, using the 101 dilution exhaustion technique. Positive samples and isolated colonies were then biochemically identified.
Sea shrimp – Vibrio: 400 ppm Citrex
Assay 1 Assay 2
Sample Vibrio spp. Sample Vibrio spp.
Sample 1 Negative Sample 1 Negative
Sample 2 Negative Sample 2 Negative
Sample 3 Negative Sample 3 Negative
Sea shrimp - Vibrio 200 ppm Chlorine
Assay 1 Assay 2
Sample Vibrio spp. Sample Vibrio spp.
Sample 1 Negative Sample 1 Negative
Sample 2 Negative Sample 2 POSITIVE
Sample 3 Negative Sample 3 Negative
Redución Mesófilos Muestras Enero
0
5000
10000
15000
20000
1 2 3 4 5 6 7 8 9 10 11 12
No muestreos
ufc/
gr
citrex
Cloro
Mesophylls Decrease – January Samples
No. of samplings
Chlorine
Reducción Mesófilos Muestra Marzo
0
1000
2000
3000
4000
5000
6000
1 2 3 4 5 6 7 8
No Muestreos
ufc/
gr
Citrex
cloro
Mesophylls Decrease – March Samples
No. of samplings
Chlorine
Reducción Coliformes Enero
0
50
100
150
200
250
1 2 3 4 5 6 7 8 9 10 11 12
No muestreos
ufc/
g Citrex
Cloro
Coliform Decrease – January
No. of samplings
Chlorine
Reducción E. coli
05
1015202530354045
1 2 3 4 5 6 7 8 9 10 11 12
no muestreos
ufc/
g Cloro
Citrex
E. coli Decrease
No. of samplings
Chlorine
CONCLUSIONS
• Microbiological studies and further result comparison showed that chlorine solutions had a lower performance (i.e.: they resulted in lower significant decreases of the organisms analyzed).
• More research is needed to further support the disinfectant effect of organic acid complexes like Citrex®.
