The MOMA Birthday Edition follow-up

All in the name of science, I sampled all eight jars of yogurt from last nights batch in various combinations.  You may wish to refer back to the table at the end of the previous post to see the difference between each jar.

Q: Is there a difference between Nancy’s Organic Yogurt culture and Voskos Greet Style Yogurt culture?

A: Not a strong difference.  Voskos may make a slightly tangier result — in a B vs D tasting, D was slightly tangier.

Q: What happens when you use almost sour milk as your base?

A: It’s not good!  The sour milk gets sour-er.  Jars A and E were so unpleasant that I set them aside and didn’t use them for more tasting.  I could maybe use them in a cake recipe, but Maria’s birthday isn’t for several months.

Q: Does heating the base first make a difference?

A: There’s no evidence that heating the milk first makes a difference.  B and F were indistinguishable, as were C and G.  Note, however, that the milk was only heated up to 120F, whereas some recipes will call for heating to 180F.  But since the point of pre-heating the milk is to kill bacteria that would prevent making a good batch, and since the batches seem fine without pre-heating, I think this step can be safely skipped in the future.  (Do any readers have evidence to the contrary?)

Q: Does it make a difference whether the jar is tightly sealed or open during incubation?

A: YES!  The answer is: don’t do it.  The jars that were sealed during incubation ended up much runnier than those that were left open: the yogurt in jars C and G (which has been sealed) was runnier than yogurt in jars that were left open during incubation: B, D, F, H.

Other: Since I ran out of milk, I made the last jar (H) with my last remaining bit of liquid milk (200 ml) and with powdered milk, mixed with 4 tbsp of powder per cup of water (500 ml).  It’s texture was fine, but once again, it had a peculiar taste — this time with a somewhat “chlorine-y” overtone.  As I write this, I realize that’s the problem: I forgot to use filtered water and used plain tap water instead.  Moral: if you’re going to use powdered milk, be sure to use good-tasting water.

The Yogurt Diaries, MOMA Birthday Edition

On this day in history: November 7 1929, The Museum of Modern Art in New York City opened.

Questions, always with the questions…

Today’s batch tries to answer a few different things:

• Is there a difference between Nancy’s Organic Yogurt culture and Voskos Greet Style Yogurt culture?
• What happens when you use almost sour milk as your base?
• Does warming the base first make a difference?
• Does it make a difference whether the jar is tightly sealed or open during incubation?

The process

As usual, I started with eight wide-mouth quart jars, cleaned and dried in the dishwasher. Each jar was given a label, A-H. The table below details the differences for each jar.

After filling the jars with 700 ml of base liquid (milk, or in one case, powdered milk, milk and water), I put four of them (A-D) in the microwave for 15 minutes. To the other four jars (E-H), I added 1/4 cup of culture, shook vigoursly and set them aside.

At the end of 15 minutes, I was hoping that the first four jars had gotten heated to at least 130 F, since many recipes call for heating the milk to 180 briefly in order to kill any bacterial. But when I measured, the liquid was only at 120 F. No matter — I went with that and put all eight jars (A-H) in the insulated cooler in a water bath. I inserted the aquarium heater and let the temperature of the liquids stabilize for an hour before adding culture to the jars that were previously too hot (A-D).

I gave all the jars an extra good shake to make sure the culture was mixed in, then removed the lids from half of the jars (see the table below for which jar got which treatment).

Culturing started at 9:30pm. I’m planning on a 7.5 hour incubation. That’s longer than usual, but I’ve been waking up at 5am regularly, so this is convenient.

Today’s Innovation

In the last batch, I put the aquarium heater in its own jar in the middle of the insulated cooler in order to keep it from falling into the water bath. My thought was that the thermal conductivity of the glass and water was good enough that everything would settle into the same temperature. It didn’t really work out that way — the water in the rest of the bath was 5 degrees cooler than the water in the jar with the heater.

Heater Holder

So in today’s batch, I simply cut a hole in the top of a plastic lid and used that to prop up the heater. While I was at it, I poked another hole in the lid and put the thermometer there — that’s much easier than dipping the thermostat in and waiting for it to stabilize each time I want to make a measurement.

This seems to be working well.

The Variants

ID	base	culture	pre-heat?	sealed?
A	“old milk” 700 ml	Nancy’s 1/4 cup	Y	Y
B	Horizon 700 ml	Nancy’s 1/4 cup	Y	N
C	Horizon 700 ml	Voskos 1/4 cup	Y	Y
D	Horizon 700 ml	Voskos 1/4 cup	Y	N
E	“old milk” 700 ml	Nancy’s 1/4 cup	N	Y
F	Horizon 700 ml	Nancy’s 1/4 cup	N	N
G	Horizon 700 ml	Voskos 1/4 cup	N	Y
H	Horizon 200 ml, Water 500 ml, Powdered 8 tbsp	Nancy’s 1/4 cup	N	N

Notes:

• “old milk” = Trader Joe’s Organic 1% with a date code of 19 October (today is 7 November). It’s not yet sour, but my nose detects a distinct tang.
• Horizon 1% = Horizon Dairies Organic 1% milk, purchased recently.
• Nancy’s = Nancy’s Organic Nonfat Yogurt, with L. acidophilus, S. thermophilus, L. bulgaris, L. casei, L. rhamnosus, B. bifidus
• Voskos = Voskos Greek Style Yogurt “Thick and Creamy Style”, with L. acidophilus, S. thermophilus, L. bulgaris, L. casei, B. bifidus. It turns out that the texture is a result of straining the yogurt, not due to any special culture.
• pre heat? = brought to 120 degrees F by putting in microwave for 15 minutes. My intention was to get it hotter — as high as 180 degrees F — in order to kill any lingering bacteria, but impatience won out.
• sealed? = cultured with the jar lid screwed on, otherwise left open for the duration of incubation.

The Results

You’ll have to check back on the next post.

The Yogurt Diaries

I’ve been remiss in describing the outcome of the previous batch.  Here it is:

Taste Tests

• Sample 081017 A: 800 ml goat milk.  At first I was hopeful for this, but for whatever reason, it didn’t set.  It was slightly thicker than the original milk out of the carton, but not much.  Perhaps goat’s milk is too acidic?  This requires some research.  Confession: I didn’t bother to taste it.
• Sample 081017 B: 800 ml Kirkland Vanilla Soy milk.  As mentioned in the previous post, the Soy Milk did set nicely, which I would have predicted if I’d done some research.  It’s texture is a little different than cow milk — it tends to form larger chunks, but not in a bad way.  Truth of the matter is that I don’t like  soy milk as much as cow milk.  Perhaps I’ll teach myself to like it.
• Sample 081017 C: 800 ml water, 3/4 cups powdered milk.  When I first tasted the powdered milk batch, I really didn’t like it as much as regular milk: it had a subtle “burned” taste to it, which is probably part of the process of making milk into powder, so I relegated it to the back of the fridge.  But when my regular yogurt samples ran low after two weeks, I brought this one out and tasted it.  Surprisingly, the burned taste had faded, so this ended up being perfectly good.  See my note below about the economics of using powdered milk over regular milk, though.
• Sample 081017 D: 800 ml 1% Trader Joe’s Organic Milk, 1/4 cup powered milk.  This one was regular milk with some powdered milk added.  It may have been a little thicker than the other samples, but I would not promise that.
• Sample 081017 E: 800 ml 1% Kirkland Organic Milk.  Good, everyday yogurt.
• Sample 081017 F: 800 ml 1% Kirkland Organic Milk.  Ditto.
• Sample 081017 G: 800 ml 1% Trader Joe’s Organic Milk.  Ditto.  I couldn’t detect any difference between samples E, F (with Kirkland milk) from samples G, H (with Trader Joe’s milk).
• Sample 081017 H: 800 ml 1% Trader Joe’s Organic Milk.  Ditto.

Note on the economics of using powdered milk versus whole milk

In local supermarkets, a gallon of 1% organic milk costs between $5.00 (on a good day) and $6.00.  I’ve been purchasing it for about $5.50.

A 12 oz bag of Organic Valley Nonfat Dry Milk costs about $7.00, and has about 40 tablespoons.  Although the ordinary directions call for 3 tablespoons per 8 ounces, they also suggest using “4-5 tablespoons for a richer taste.”  If we use the metric that 40 tablespoons makes ten 8 ounce servings (80 ounces), that’s just 5/8 of a gallon for $7.00.  If we made a full gallon, it would cost us $11.20 to make a full gallon.  Not a particularly good bargain.

On the other hand, it is possible to buy powdered milk in bulk.  But even then, the prices I see aren’t particularly good: Amazon (HerbalLoveShop.com ?!?) sells 5 lbs for $36.  If 12 ounces of dry milk makes 5/8 gallons of liquid milk, then 5 lbs (80 ounces) will make 4.16 gallons of liquid milk.  That’s still much more expensive than buying a gallon for $6.00.