Yogurt Making at the Farm

On what has been possibly the coldest day in January to date, I joined Sarah, Alan and Josh for the afternoon as they bottled Stonewall Farm’s freshly made yogurt. Glenn, our dairy farmer, was understandably absent, as he had awoken at 2:30am to begin the process.

Making yogurt is fairly straight forward and can be done from the comfort of your own home (but we will save you hours if you eat ours!). Today I am going give you an overview on how we make yogurt at Stonewall Farm. I invite you to use it as a basic guideline for making your own yogurt. While we use a pasteurizer, you can replicate the process on a good old fashioned stove top. We have also included at the end of this post, our commercial yogurt recipe for anyone who wants to use it. While these are usually kept a better secret than your grandmother’s pie recipe, we figure that our job as an educational farm is to help spread knowledge!

Click on the first thumbnail (the cow head!) to begin the slideshow with a full explanation of the process:

1. First we milk our cows! Our herd is a mix of Holsteins and Brown Swiss, which are both high milk producing breeds.

2. We pump milk from the milk tank to our pasteurizer. Here you can see our micro-pasteurizer, which was purchased in 2011. Another post on the benefits and drawbacks of a micro-pasteurizer to come soon.

3. We pasteurize the milk for yogurt. (Why? Because pasteurization slows microbial growth by killing bacteria, the culprit behind food spoilage.) To pasteurize, we heat milk to 175°F and maintain it consistently at this temperature for 30 minutes. Here you can see the log of our pasteurization process which is maintained for review by our dairy inspector.

4. As the temperature gets to ~160°F we mix in powdered milk and sugar. We quickly cool the milk to 112°F. We cool the milk by draining the hot water and adding cold water to the micro-pasteurizer which has a special tank within it separate from the milk.

5. We add the live cultures and our yogurt probiotic mix. For all you biologists out there these are the bacteria added: S. thermaophilus, L. bulgaricus, L. acidophilus, Bifidus lactis, Bifidus infantis. We then maintain our live culture infused milk at 112-115 degrees for a steady 8 hours. This is called culture time.

6. We pump the yogurt from the micro-pasteurizer through tubes to the bottling unit.

7. We fill up the quarts with yogurt.

8. Here Sarah and Alan work as a team to bottle and seal the yogurt using a sealing machine.

9. Sarah demonstrates the small suction tool she uses to put seals on the quarts. This takes some fine motor skills!

10. Alan shows off the bottled yogurt.

11. We crate the yogurt up and it is ready for transportation to the chiller.

12. We load the yogurt into Josh’s car to drive it from the barn to our chilling unit – very official!

13. We unload the yogurt and put it in the CoolBot to bring the temperature down to 40°F. Here Josh makes room in the CoolBot for the yogurt.

14. The finished product! Labeled and ready for purchase at our farmstand.

15. Now it is back to the barn – it is time for some heavy clean-up, including washing and acid rinsing all the equipment we used.

Stonewall FarmVat Pasteurizer Yogurt Recipe

Makes approximately 200, 6 oz cups and 20, 1 quart tubs.

Equipment
Micro scale for weighing culture (we use My Weigh scales, http://www.myweigh.com)
Regular scale (up to 20 lbs or so), for weighing other ingredients

Ingredients
20 gallons milk
22 cups of sugar (approximately 10 lbs)
2.3 grams of culture
6 lbs of non‐fat powdered milk
25 ounces vanilla

Steps
Best to start process around 3:00 – 3:30 am in order to allow time for culturing (8 hours) and then bottling in the afternoon.
1. Pasteurize milk at 175 degrees for ½ hour.
2. Drain hot water in vat and add cold water. As temperature gets to ~ 160 degrees mix in powdered milk and sugar.
3. Drop the temperature to at 112‐115 degrees and hold it there. Add culture. Hold temperature for 8 hours.
4. Before bottling stir the yogurt for 15‐30 minutes with the agitator (set at highest speed), starting with the paddle near the top of the yogurt and moving it down a few inches every 5 minutes or so. Leave the paddle turning at the bottom (without scraping the vat) during bottling.
5. Turn of the vat heater and drain the hot water from the vat.
6. Bottle the yogurt, and refrigerate below 40 degrees.