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High TPC count on vacuum pack salmon


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#1 Amanda.E

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Posted 23 August 2013 - 08:11 AM

Recently did a test on raw vacuum packed salmon.

We sliced one salmon into fillets at the central kitchen before vacuum packing (total 7 packets). These samples are stored in chilled conditions at the central kitchen and delivered daily to the outlet before the lab picks it up from there. We were extremely careful during processing at central kitchen, taking care to sanitize work area.

 

Our chef went down to the outlet and processed one salmon there. Salmon fillets are cling wrapped and stored in the chiller with the vacuum packed salmon. There has no form of sanitization at the outlet.

 

Day 1 & 2, sent two packets to outlet. One collected in the afternoon and one collected the next day.

 

These are the results:

Day 0 (Collection at central kitchen): 940 CFU

Day 1 (Collection at outlet): 6800 CFU

Day 1 (Collection at outlet, after storage overnight): 54,000 CFU

Day 2 (Collection at outlet): 23,000 CFU

Day 2 (Collection at outlet, after storage overnight): 13,000 CFU

 

Outlet results are all less than 700 CFU even after storage for 3 days in cling wrap.

 

The lab that conducted the test said that it could be because it is a different fish / different part of the fish.

I would like to know if it is possible for a vacuum packed fish that is stored in chilled conditions to have such a high count as compared to one that is cling wrapped. If so, how? could the bacteria multiply in these conditions?

 

Thanks!

 

 



#2 Charles.C

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Posted 23 August 2013 - 02:11 PM

Dear AmandaE,

 

Thanks for the post.

 

Unfortunately, (and maybe it's just me)  i was unable to understand the details / chronology of the flow processes you were presenting-comparing. It might be easier if you attached a flow chart. The actual chilling temperatures / times would be useful.

 

The usual way of microbiologically studying a fish filleting process is to measure the item,eg plate count (specified procedure-time/temp) at each stage while controlling the product temperature/time/ in a known way. Including the pressure if relevant as present case.This particularly includes the first stage, ie raw material. It is also critical to get an idea of the sampling / measurement variation for counts on product at the same stage which can be surprisingly large. This involves the use of duplicates.

 

Hopefully other people understood the situation more clearly.

 

Rgds / Charles.C


Kind Regards,

 

Charles.C


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#3 Charles.C

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Posted 26 August 2013 - 10:35 AM

Dear AmandaE,

 

I would like to know if it is possible for a vacuum packed fish that is stored in chilled conditions to have such a high count as compared to one that is cling wrapped. If so, how? could the bacteria multiply in these conditions?

 

 

I presume the fillets are all skin-off.

 

Bacterial growth for a filleted / stored item can be impacted / reduced by  various techniques;  eg vacuum, MAP, pressure can slow it down compared to “untreated” items. But the degree of difference depends on many factors, eg  species, source, initial micro.flora, storage time / temperature control  / initial overall microbiological conditions, packaging permeability, etc. In some cases, a growth lag can be achieved.

 

Although I got lost at the part of yr text starting “day1 & 2 >> …” I can illustrate some possible effects for tilapia / salmon fillets with some lit. graphs  in the excel document attached   –

 

Attached File  micro quality chilled fish fillets.xls   458KB   27 downloads

 

Hopefully of some relevance

 

Rgds / Charles.C


Kind Regards,

 

Charles.C


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#4 Amanda.E

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Posted 27 August 2013 - 11:26 PM

Central kitchen Procedures

Date

Activity

12/8/2013

  1. Wash chopping board, utensils with ROX alkaline and acidic water
  2. Soak chopping board in acidic water overnight
  3. Keep one box of fish

13/8/2013

  1. Remove chopping board from acidic water. Wipe dry and dry sanitizer on chopping board and all utensils
  2. Wash fish with alkaline water and then acidic water after de-scale.
  3. Check room temperature
  4. Check temperature of fish
  5. Slice fish
  6. Soft vacuum application used
  7. Keep fish in chiller immediately after vacuum pack
  8. Lab collect sample at central kitchen (Day 0)

14/8/2013

  1. Fish is delivered to outlet
  2. Lab test collection (Day 1 #1)

15/8/2013

  1. Fish is delivered to outlet
  2. Lab test collection (Day 1 #2, Day2 #1)

16/8/2013

  1. Lab test collection (Day 2 #2)

#1 : Collected on same day, 4pm

#2: Collected after overnight storage in outlet

 

 Outlet Procedures

 

Date

Activity

14/8/2013

  1. Delivery to outlet (whole fish)
  2. Chef process fish upon receiving
  3. Normal cling wrap. Keep in chiller.
  4. Lab collection at 4pm. (Outlet day 1)

15/8/2013

  1. Lab collection at 4pm. (Outlet day 2)

16/8/2013

  1. Lab collection at 4pm. (Outlet day 3)

 

Results

 

Sample

CNK Day 0

CNK Day 1 # 1

CNK Day 1 # 2

CNK Day 2 # 1

CNK Day 2 # 2

Outlet Day 1

Outlet Day 2

Outlet Day 3

Date tested

13/8/13

14/8/13

15/8/13

15/8/13

16/8/13

14/8/13

15/8/13

16/8/13

TPC cfu/g

940

6,800

23,000

54,000

13,000

310

500

260

CNK: Central kitchen

#1 : Collected on same day, 4pm

#2: Collected after overnight storage in outlet

 

I hope this clarifies the procedure. We find it unlikely that the TPC counts for raw salmon after storage in the outlet for 3 days to have a count of only 260 while a vacuum packed one is 54,000. Could it be a problem with the vacuum if storage and delivery temperatures are good? Fishes used are from the same box (4/box).



#5 Amanda.E

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Posted 27 August 2013 - 11:45 PM

I didn't realize the tables won't show. :( No idea how to delete the post too  :helpplease:

This is the url for the process: http://i1010.photobu...zps198eb72d.png

I hope it works!



#6 Charles.C

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Posted 28 August 2013 - 08:06 AM

Dear AmandaE,

 

Thks for reply. I presume this is the data you were trying to show. –

 

Attached File  salmon.pdf   32.8KB   15 downloads

 

Assuming starting  steaks of similar origin / microbiological quality for each run (vacuum / cling wrap) yr data suggests IMO that there was something fundamentally different in the control / evaluation of the 2 runs. It looks to me like something went “wrong” during the vacuum run. Or the latter's samples were simply widely micro-variable from the start  for some unknown reason. Or different lab analysts were involved. :smile:

 

As per my previous post, relevant data is absent, notably times,  temperatures and duplicate data. I fear this makes any comparison rather difficult / impossible.

 

I suggest a run comparison more like this (the data should be recorded) -

(I presume the raw material is frozen whole fish.)

(I presume you intend to commercialise  raw, skinless, cleaned, boneless, steaks.)

 

Select 1 whole fish (I presume stored frozen). (If 1 fish not adequate to generate enough sub-samples, multiple controls as described below will be required.)

 

Sample aseptically the meat below the skin in at least 2 “representative”  locations.

Measure psychrophyilic / mesophyilic (PSC/MSC) counts on each sample at defined temp/time.  Results should be within “reasonable” agreement, eg not 1000 and 100,000 cfu/g respectively.

Thaw whole fish(es) under controlled conditions until usably softened, eg in a refrigerator, 0-5degC

Measure temperature of softened fish in at least 2 representative places. Should be 0-5degC.

 

Process fish to yield enough (cleaned, skinless, boneless) steaks for subsequent testing. Note ambient temperature, eg 25degC.

Meat temperatures should be checked periodically, eg every 10min and  maintained at 0-5egC during above step. Total “step” should be carried out within 30mins.

minimum 2 random steaks selected for PSC/MSC. Results should be within “reasonable” agreement.

 

Carry out the respective vacuum wrapping / cling wrapping procedures as desired. Input product temperatures should be monitored and maintained within 0-5degC. Immediate transfer to chiller. Chiller temperature should be uniform, monitored, maintained at 0-5degC for the different runs.

 

For each run, take minimum 2  samples at successive days (same storage intervals) and measure sample temperature /PSC/MSC.

 

I would also include some dummy samples of “known” quality  if 3rd party lab sampling / testing is done.

 

Rgds / Charles.C


Kind Regards,

 

Charles.C


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