A Hummus problem

[chillywilly2]

A customer has an existing walk-in cooler box which they want me to use for the purpose of rapidly chilling their product. (Hummus, a chick pea paste of coarse peanut butter consistency)

I am trying to confirm package dimensions w/customer, but at this time they are using food-grade 5 gallon containers, placing them in a 36F cooler with a rapid chill ice tube container in the product. This method is not sufficient to satisfy health department regulations.

The batch size is 2500 lbs @ 140F and they need to drop the product from 140F to 40F in 4 hours. A 100F temperature drop. The product will enter the box incrementally over the course of an hour.

The specific heat above freezing is 108F and my calculations indicate a need of .78 BTUH (per pound?) beyond the BTUH already required to cool the space. The box dimensions are 23'Lx13.5'Wx10'H or 3,105 cuft. The existing refrigeration system is medium temp, but this need not remain so. Freezing of the product needs to be avoided.

What I am trying to wrap my brain around is this: In order to obtain the required temperature drop of 100F in 4 hours in a fairly dense product, what formula or calculations can I use to determine the proper box temperature at which to keep the box?

Thanks in advance!

[Magoo]

The problem is getting core temperature down to spec within the required time frame. So you will need to hit 5 gallon containers with a high draught air flow at a lower temp than 36'F. The outer temps of containers will be lower than specified but internal /core temps will equibulate. { balance out } . Its a fine line. What will the effect be on product at lower temps on the outer area of 5 gallon container.
I have done the similar product, but in finished on the shelf delivery containers/ pots. Way smaller than 5 gallons.

[mad fridgie]

Unless you know the thremal properties of the product, then you would only be guessing.
my advice would be to chill the product before entering the container "scrapped surface heat exchanger"
If you want to continue with this method then I suggest you do a simple experiment.

Place your filled container (temp sensor in the middle of the product) into a bucket filled with ice water, add alittle air to ice water, for agitation. Add ice as required. Time how long it takes to cool to required temp. If within the alotted time scale, then we can look to transfer the data to chiller air. The problem is the product not the chilling medium. If not then chill at source.

[chillywilly2]

Magoo and Mad Fridgie,

Thanks for the responses. I have advised customer already that pre packaging in their <1lb containers would be most effective, as their would be a possibility of freezing outer product prior to achieving temp at the core of a 5 gallon bucket. (I enjoyed the use of "equibulate" in a sentence!) As far as the pre-chill prior to packaging, the cosistency may be an issue, but a similar method is used in some older breweries, a "cool-ship" or large chilled copper plate at an incline, has the beer wort ran over it. I suppose a chilled barrel/auger or screw set up would work with this thicker product. It appears that I will need to conduct an experiment to obtain some data on different sized containers. I will post back with the results ASAP.

Thanks again.

[chemi-cool]

Hummus in that stage is full of liquid, therefore it will cool pretty quick.
Do not go too low as it has oil in it [olive oil I hope]. Too low temp will separate the oil.
Use evaporator fans with higher air quantities and you will not have any problems.

We eat it almost every day, [home made], Stick it warm into the fridge and eat it the day after.

Good luck with it.

[Magoo]

Hi Chemi
your wifes receipe. I really like hummus

[Fri3Oil System]

a stupid question, falafel is made with hummus? at least they have the same ingredients?
Yeah, maybe I should go to a cuisine forum:off topic: sorry there, but I love cooking and have made falafel several times, love it!

[chemi-cool]

Hi Chemi
your wifes recipe. I really like hummus

In which language?
pm me your email.

Fri30Oil,
Yes, falafel is made from hummus and other ingredients, but the main part is grained hummus.

[chemi-cool]

Searching the web, In found this site, looks good.
http://humus101.com/EN/2006/10/14/hummus-recipe/