Criteria for defrosting frozen raw materials safely

is there any equipment to speed up defrosting big batch raw material?
or what is the right procedure for a food company to defrost frozen raw material?

The following is the procedure i m going to write up

1.0 objective
.............
2.0 procedure
Defrosting food safely is essential in preventing food poisoning. All food must be kept at a safe temperature (< 5 ºC) during defrosting.
2.1 chill room defrosting
........................
2.2 cold water defrosting
................................

Dear TinaZ,

It maybe depends what you mean by “big” batch. Of the order of 1 ton up??

Hv seen all 3 of yr mentioned techniques used for frozen seafood. Some systems are bought in, some are custom made but I don’t hv any references off-hand, sorry.

The specific choice probably depends on various factors, eg desired efficiency (weight loss, time, temp.control, etc), the product type / damage sensitivity, local environment and available materials, eg water, amongst others.

IMEX, strict adherence to 5degC is often difficult, hv seen up to 10degC used.

Rgds / Charles.C

Air temperatures are sometimes surprisingly high but I would be wary about straying above 5 degrees. IMO it's very important to monitor core and surface temperatures; they can be surprisingly different. Bit more info?

Dear Tina Z,

Same as the two other members, I think it will be interesting to know your process steps. Why it has to be 5oC? Here are some links which also discussing similar topic like yours:

http://www.ifsqn.com...showtopic=10790

http://www.ifsqn.com...showtopic=11209


Regards,


Arya

5 degrees is the limit of growth of a few pathogens. In one site we validated that we could get a core temperature of zero and a surface of 5. It's obviously easier to defrost if you heat up the surface loads but most defrosting units use a combination of surface and core temperatures to control and as the product gets closer to being defrosted, it reduces the temperature to avoid surface hotspots.

I think 5 is a good rule of thumb; 8 would be the limit for me.

I think 5 is a good rule of thumb; 8 would be the limit for me.

Makes senses for me. I'll make sure to keep that in my mind whenever running the meat process. Thanks.

Can I ask what the frozen material is? Maybe it has already been mentioned in the thread, maybe it does not matter??

Dear Arya,

I guess the most famous exception to the 5degC (or often 4.4 in USA from memory) guide is L.monocytogenes (as I suspect you already know).

And the most common exceptions to the operational 5degC guide are probably in the tropics (ambient temperature 30degC up !)

As a corollary to Simon's post, the eventual pathogenic-related consequences of not following the guide will depend on the product, its starting microbiological characteristics and the following process (eg, RTE or not, any kill steps or not).

Rgds / Charles.C

Listeria can grow at zero but not quickly. The peak growth rate is around 30 something from memory. The 4.4 you're thinking of is the pH I believe?

Dear GMO,

Re 4.4, guess I was remembering this earlier link –

http://www.fsis.usda..._Thaw/index.asp

The Americans do love their Fahrenheits !

To illustrate the diversity of opinion - another, claimed validated, earlier link (and a prestigious website I believe) -

Validated Critical Limits based on study results:
• Intact chicken (frozen at -4°F or colder) weighing 3.68 lb or more can be thawed up to 9 hours at a temperature up to 86°F
• Ground beef (frozen at -4°F or colder) weighing 3 lb or more can be thawed up to 9 hours at a temperature up to 86°F
• Ground beef (frozen at -4°F or colder) weighing 1 lb or more can be thawed up to 9 hours at a temperature up to 72°F
http://meathaccp.wis...zen_chicken.htm

(note that the quoted temps are for the surrounding environment)

Have little doubt many people will be uncomfortable with the second one (including myself). Probably is counter to most current published HACCP plans. Guess it rather depends on their validation of “significant” growth for one thing.

Rgds / Charles.C

Can I ask what the frozen material is? Maybe it has already been mentioned in the thread, maybe it does not matter??

Thank you for everyone's kind replies. all your information is very useful.

the frozen materials defrosted in our site include duck leg, beef slice and shredded duck meat.

I think the air temperature is less important than the product temperature. Naturally the air temperature has to be raised for defrosting to take place in a reasonable length of time as long as it's all validated around what temperature the product reaches.

Spreading out the food (if it's IQF) can help but I'd put a cover over to prevent drying out, e.g. a piece of plastic (food safe, distictive colour and decent thickness e.g. 45 micron plus before I get the foreign body police whipping out a baton on me!)

Validated Critical Limits based on study results:
• Intact chicken (frozen at -4°F or colder) weighing 3.68 lb or more can be thawed up to 9 hours at a temperature up to 86°F
• Ground beef (frozen at -4°F or colder) weighing 3 lb or more can be thawed up to 9 hours at a temperature up to 86°F
• Ground beef (frozen at -4°F or colder) weighing 1 lb or more can be thawed up to 9 hours at a temperature up to 72°F
http://meathaccp.wis...zen_chicken.htm

I would be comfortable with the surrounding temperatures till 10oC max for thawing, temperatures upto 30oC is questionable for 9 hours. Maybe thorough cooking can eliminate any hazards, could be the point behind the time/temp in the thawing process.