Meat room

[G Cook]

Hello everyone,

One of our customers has been complaining about fresh red meat losing its colour in one of his cold rooms. We were in the premises today and happened to notice pork in trays soaking in a curing solution on the floor of the room (curing bacon). This is a saltpeter and brown sugar curing solution.

Does anyone have any idea if this solution could cause the other meat hanging within the room to discolour?

Thanks in advance

[lawrence1]

Fluoroscent lighting will discolour meat and hams,,in display cases and coldrooms,,if your coldrorom has fluoroscent lights you need to fit the (pink shade)similar to NEC Biolux BRB tubes.if you google promulux i think it is,,,there is info there which is interesting.
Lawrie

[chilliwilly]

How long have they cured the pork for? Some of the butchers shops that I look after usually do that as well as brining beef. And they have had no problems with it affecting the colour of other meat in the past 50 years. Like lawrence 1 says could be the wavelength of the lighting.

Take a peice of meat to another part of the shop and see what colour it is under a different light. And I know that you don't need me to say this, but make sure that the walkin is holding temperature and that their meat deliveries are fresh.

[old gas bottle]

i would check the defrost settings, are the fans coming on too soon blowing warm air onto the meat ,is there a drip down timer and is the stop temperature too high.;)

[chemi-cool]

Lights and oxidation are the causes for meat discolour.

lawrence1 has the answer for the lights.

[G Cook]

Thanks for all your input guys, it is appreciated.

There are no fluoroscent lights within the room so this should not be a problem.

As far as we are aware the curing trays are a fairly recent addition (not 100% sure how long). We were going to ask them to move the trays to their other room to see if the problem persisted, as the meat within the other room does not lose its colour.

Room maintains temperature without any problem, cuts out at 0 and back on at 2 degrees. As for defrost settings I'm sure they are as follows -
4 - 20 minute defrosts in 24 hours
Defrost termination temp 12 degrees (evap temp)
3 minute drip time
Fan restart temp 6 degrees

The butchers describe it as the meat losing its bloom, if this means anything to you guys? When the meat is delivered it is split between the two rooms within the shop, its only the meat within this room that has the problem. If the meat is covered then it is ok. Any ideas?
What causes oxidation?

Thanks again guys :)

[chemi-cool]

I set defrost termination temp for 8°C, sensor at the top of the coil.

Fan start temp at 0 or 1°C. if non it will throw warm humid air inside.

Another thing that came to my mind is how clean the evaporator coil?

[G Cook]

Thanks for the advise on the settings, i'll give them a go.

The equipment on this room is new so no problem there. The old equipment (very old) was undersized for the room, (its a busy little room, door opened and closed a lot). Condensing unit used to run constantly through the day attempting to maintain temperature. We thought that this was dehumidifying the air within the room reducing humidity and causing the meat to lose its bloom. However new equipment has been installed which is up to the job and still the problem persists :confused:!!?? (Although the butchers do say it is not as bad as it was).

Any more thoughts on oxidation?

[DTLarca]

What's the room humidity? What is the blowers effective SHR :)

[G Cook]

Not sure what the room humidity is. However the equipment is more than up to the job so not to long a run time.

What else would affect the humidity within the room?

[DTLarca]

Not sure what the room humidity is. However the equipment is more than up to the job so not to long a run time.

What else would affect the humidity within the room?

Too little run time will raise humidities.

Terminating defrosts too late and bringing on the fans too soon after a snap freeze will somewhat raise room moisture content but the blowers operating TD is the most important factor. If the blower is over sized for the application the TD will be low and so the humidity up and the meat will darken and be difficult to manage under the blade.

You can move the TEV phial into the tubes to shorten the effective length of the evaporator or you could just increase the TEV static superheat setting by say 3 degrees which will lose you about (0.3)^3 = 9% capacity but will lower the humidity.

You could also use a humidity stat to cycle one of the evaporator fans.

[G Cook]

The meat appears to be drying out rather than being attected by high humidity. There is no sign of high humidity in the room such as slimming of the meat etc.

The problem first occured whrn the room was still running with its old undersized equipment.

[DTLarca]

The meat appears to be drying out rather than being attected by high humidity. There is no sign of high humidity in the room such as slimming of the meat etc.

The problem first occured whrn the room was still running with its old undersized equipment.

Then surely the humidity is too low and or the air velocity is too high - yes?

Do you know the precise humidity and the air velocities over the meat?

[G Cook]

Yes I would agree with you about humidity etc, unless there are any other factors which can affect the meat that I don't know of??

Is there anything else, such as something within the atmosphere of the room :confused: that could cause this?

As for the humidity i don't have psychrometer so can't help much there.

[DTLarca]

Quote from my copy of ASHRAE Handbook: "Standard holding room practice calls for providing enough

evaporator capacity to keep the room temperature at 0 to 1°C at all times. Holding room coils sized at peak load, low air/vapor circulation rate, and a coil temperature 5 K below room temperature tend to maintain the approximately 90% rh that avoids excessive shrinkage and prevents surface sliming."

[Gary]

As for the humidity i don't have psychrometer so can't help much there.

In a pinch, you can wrap a little wet toilet paper around your temp probe to get a wetbulb temp.

[G Cook]

Thanks for your input guys.

DTLarca as our equipment has been worked out for the room in question, plus the fact that the same problem was present while the old equipment was in use you would have to assume that there is another factor causing this, would you agree?

I'll give that a try Gary, I suppose the differance between wet bulb temp and dry bulb temp will give an indication of humidity?

I'm guessing from what everyone is saying that there is little else that could cause this problem with the meat, is that the case?

[Gary]

Fortunately, you have a second room to compare to. Check the air on and air off temps (drybulb as well as wetbulb) in both rooms. This should give you some insight into the problem.

Does the system have an EPR valve?

[old gas bottle]

one last thing, are the evap fans running all the time exepting defrosts !,if they are try setting the controller to let them run while the compressor runs only.might help.;)

[chilliwilly]

Is there any way you can set up a pen recorder or a data logger in there for a twenty four hour period? This will point you in the right direction to your problem as it does seem to be a tricky one. You may need to increase the amount of defrosts and adjust the defrost time and termination temperature.

[DTLarca]

Thanks for your input guys.

DTLarca as our equipment has been worked out for the room in question, plus the fact that the same problem was present while the old equipment was in use you would have to assume that there is another factor causing this, would you agree?

I don't believe you would "have" to assume there is another factor just yet. But it would also be erroneous to simply assume it must simply be a matter of poor sensible heat ratio control.

I and others have put forward a few ideas on how to decrease the overall SHF and someone also mentioned a way the overall SHF could be raised.

Among other reasons in addition to a lack of condensing pressure control causing SST's to drop in turn reducing SHR there is often a dependence on Evaporator Pressure Regulators to raise sensible heat ratios.

You should first eliminate room humidity and air velocities as the potential problem before moving on. You may need to add an EPR to raise the SHR before moving on to the next problem such as poor SHR's at some storage facility further up the cold chain.

You say "We were in the premises today and happened to notice pork in trays soaking in a curing solution on the floor of the room (curing bacon). This is a saltpeter and brown sugar curing solution."

I am not at all qualified to comment on this scenario's potential contributions to the situation - I am totally ignorant here.

[mad fridgie]

Is ALL the meat in the room being affected, or just some in specific areas. With weight loss as indicated by others then the evap temp low. One issue.
If i remember rightly??? salt peter is an oxidising agent, may be your meat is oxided, discolouring the meat.

[DTLarca]

Is ALL the meat in the room being affected, or just some in specific areas. With weight loss as indicated by others then the evap temp low. One issue.
If i remember rightly??? salt peter is an oxidising agent, may be your meat is oxided, discolouring the meat.

I don't know how much weight a certain cut would normally lose per day in the ideal cold room environment. I'm being lazy - I should look it up in my ASHRAE manuals. But perhaps logging the weights of specific cuts each day would help here too. making comparisons with a room known not to have the problem.

[G Cook]

Yes all the uncovered meat within the room is affected. Evap fans run continously except on defrost. No EPR valve on the system.

Sounds like we should be looking at room humidity. Next time we are in we will take the wet and dry bulb readings.

In the mean time going to ask the butchers if they can move the curing trays into the other room when they recieve their next meat delivery just to eliminate this if nothing else.

Thanks for all the ideas guys, keep them coming, very helpful! :)

[Gary]

Since meat is sold by weight, it is worthwhile keeping the humidity up even if this is not the problem.

[G Cook]

Good news, curing solution was removed from the room at the beginning of the week and this appears to have stopped the discolouring of the meat.

A happy butcher :D

Thank you all for your input, very helpful!

[DTLarca]

Good news, curing solution was removed from the room at the beginning of the week and this appears to have stopped the discolouring of the meat.

A happy butcher :D

Thank you all for your input, very helpful!

Cool - I learned yet something more :)