Commercial Yogurt Maker

[Alex of the North]

In our coffeehouse we go through about 2 gallons of yogurt a week, mostly in the form of yogurt parfaits (with berries and granola). We'd like to start producing our own yogurt, and I've been experimenting with this at home. I'm pretty satisfied with the quality of what I'm doing, but when it comes to doing it at work, I'd like a process that doesn't involve constantly monitoring the temperature, etc. I was wondering if anyone has any experience making larger quantities of yogurt in a restaurant setting, and whether anyone can point me to a durable appliance that makes more than a quart at a time. Thanks!

[cdh]

Think a round cooler and an aquarium thermostat. You're looking to keep the milk and bugs at about the temperature of a tropical aquarium... and a cooler will keep the power draw to do so low. I doubt you'll find a commercial one-purpose device that will cost less than those two devices together.

[Joe Blowe]

Also, check with your local health department -- there might be some additional requirements or restrictions for a restaurant that is manufacturing/processing food, rather than just selling it...

[Alex of the North]

Both great suggestions! I'll have to look into that...

[dougal]

Its probably easier to keep the temperature steadier with larger quantities.

Have you considered (or are you) making your yoghurt in a vacuum flask?

IMHO, thats the easy way.

And with a bigger flask, it would hold the temperature for even longer - there should be more volume (so product thermal mass) in proportion to the external surface area (and thus rate of heat loss - assuming the insulation is the same).

Since you are going to be aiming for a fairly low temperature (~ 40C/100F) the rate of heat loss from a flask would be much slower anyway than when used at more normal "hot drink" temperatures of 60C and above

It seems that larger sizes (like 5 litres, 1.3 us gallons) are more readily available in "airpot" designs. You don't need the dispenser, but if that's the easy way to get the flask...

However, I suspect that you may find that making daily (nightly?) batches of 2.5 litres makes more sense than fewer larger batches - and it should open up more choice of vacuum flask.

Quantities. 2 us gallons per week is only like 8 litres in probably 6 days. Lots of home yoghurt makers would make 1 litre at a time in a vacuum ("thermos") flask.

Regarding the product volume, if you are planning to make a 'strained' (greek-style) yoghurt, then you are going to lose volume with the straining, so you'll have to make more!

[Alex of the North]

I've actually been using a Nissan Thermos French Press in my experiments at home, but I hadn't really considered this for the shop. Most of the airpots (we have quite a few) have very narrow openings, which would make them difficult to use for yogurt. Are there any 128 oz thermoses with wide mouths out there?

[judec]

I use large stockpots or dutch ovens to make 2+ gallon batches at home and I've been getting consistently great results. Fermentation happens in a warm oven with the lightbulb on - it's hot enough to keep the oven at about 100 F (on my oven, at least).

It might be worth experimenting with.

[dougal]

... Most of the airpots (we have quite a few) have very narrow openings, which would make them difficult to use for yogurt. Are there any 128 oz thermoses with wide mouths out there?

←

I can't help with what the US market might have on offer...

... BUT it did occur to me, quite some time after posting, that one of the best things might be a "thermal cooker".

These are rather well insulated containers (with wide openings and insulated lids) and large capacities.

I had a look on Amazon US, and noticed that you can get a cheap 6 litre capacity (200 ounces?) "thermal cooker" for (just) under $50.

http://www.amazon.com/Sunpentown-ST-60B-Th.../dp/B000Q94CMM/

I've no idea if this particularly cheap example is a good "thermal cooker" - but then, does it need to be?

I happen to loathe the term "thermal cooker", but it wouldn't prevent me stopping by to try the yoghurt if I happened to be passing by!

[Alex of the North]

That's pretty much the conclusion that I've reached... I've discovered that setting a stainless steel pot on top of our commercial convection oven and beneath the oven hood, maintains a temperature of about 95 degrees, which is pretty good!

[slkinsey]

Alex, how much are you willing to spend?

The easiest way to make this much yogurt would be to put containers of inoculated milk into a temperature-controlled water bath. The easiest way to get a temperature-controlled water bath: drop 500 bucks on a used/reconditioned recirculating laboratory water bath heater. This you can clip to a hotel pan of sufficient depth or other vessel (you want the water bath at least as deep as your milk containers), fill with water, heat to set point, insert your containers of inoculated milk and you're good to go. Your volume is limited only by the size of your water bath.

As an added benefit, all you need to do is purchase an edge-sealing vacuum machine and you've got a sous vide setup as well.

[Alex of the North]

Not that much! I've already investigated the recirculating water baths... perhaps down the road, I think I'd have to find about two more practical applications for it to make it worthwhile. Are there many vegetarian sous vides recipes? But for now, I'm going to try stockpots and adjusting conditions around them.

[judec]

I've discovered that setting a stainless steel pot on top of our commercial convection oven and beneath the oven hood, maintains a temperature of about 95 degrees, which is pretty good!

←

If you can maintain a temperature a few degrees just under 90, the texture will be much better. It will, of course, take longer to ferment but it's worth it.

[pounce]

Fish tank or similar

Waterbed heater with thermostat control

Sandwich the heater under the tank. Heaters and tanks come in different sizes so you might need to play around a little with positioning the heater. I'd suggest putting a cloth between the glass and the heater to cushion the edges of the tank so they don't damage the heater.

Fill the tank with enough water that when you put your yogurt jars in it the water doesn't go over the rims. I use quart size mason jars and they work well.

Switch on the waterbed heater and dial in your desired temp. Most of these heaters only go to 100F.

The water is really going to help distribute and stabilize the heat.

This setup might only cost you $75 if you went with new equipment. If you used Craigslist or thrift stores or neighbors garages you could probably do it for free or very little.

[Channie]

I use one of those $1.99 foam coolers available at drugstores and supermarkets this time of year. I fill wide-mouth canning jars with the yoghurt mixture, elevate them inside the cooler, and fill with warm water almost to the top of the jars. The water maintains its temperature inside the cooler, and the yoghurt sets in about 3 1/2 hours. By changing the water temp, I can change the tartness of the yoghurt. The most I've made at one time is 2 quarts, but there's no limit, as long as the jars fit inside.

You might want to try something cheap like this -- at least until you're sure that "homemade" yoghurt fits into your schedule.

One more thing -- you might find quart or half-gallon containers to be more efficient than large gallon containers in terms of storage. And if you'll be using the last batch as starter for the next batch (which I'm sure you will do), it's nice to take starter from a newly-opened jar, rather than one that's been opened and closed and scooped from many times.

[zoe b]

I make a gallon at a time--I use 2 Tupperware rectangular lidded pitchers.

I put a heating pad in the bottom of a cooler, place a plastic lid on top of it to keep the pitcher bottoms off of direct heat, put the pitchers in and leave them for seven hours.

Perfect every time.

Zoe