Yogurt Making Tips and Techniques

When I blogged about my collection of contradictory yogurt-making advice last month, I promised to share my test-kitchen results. I've tried most of the different tips and recipes I read about. Here is what worked for me, and a what didn't.

• Apparatus. I use a yogurt-maker, a Salton I got on sale at amazon.com several years ago. I've made yogurt in coolers filled with warm water, in a dehydrator, and in a warm oven. All these things work, but the small yogurt maker is most consistent, and these days it costs about $25. (Watch for sales; sometimes it's quite a bit cheaper.) I replaced the cheesy little plastic yogurt bucket with a quart size canning jar.
• Batch size. I make yogurt one quart at a time, and find it the easiest quantity to manage. Many recipes are aimed at people who need to use surplus milk (people who milk goats or cows; people who shop the sales). I like yogurt, but a gallon or two at a time is a lot for me to use up.
• Powdered (instant) milk. I find yogurt made entirely from instant powdered milk has the same taste and texture as yogurt made from fresh milk supplemented by a little powdered milk. Time was when instant powdered milk was much cheaper than fresh, but when I checked my local grocery store in April, a gallon of skimmed milk cost $3, while a box of instant powdered milk sufficient to make two gallons cost $9.25. That's 50% more for powdered milk. The advantage of all-powdered milk is convenience: you don't have to scald it.
• Scalding the milk. If you make yogurt with pasteurized milk from the grocery store, you need to scald it. Some people don't bother, and it often works well enough. However, you don't want to smell what happens when the microorganisms that survive pasteurization (often Pseudomonas is among them) take off and outgrow your yogurt culture. I recommend you scald storebought milk. Scalding milk involves heating it to 180-190 degrees F, and allowing it to cool down to yogurt incubation temperature, 110 degrees F. If you do scald on the stove top, you need to watch and stir so that the milk doesn't scorch. You can do it in the microwave, but you also must watch so that it doesn't boil. I prefer the microwave because it reduces exposure to airborne microorganisms (and ladybugs) while heating.
• Yogurt culture. Where I shop, plain yogurt and active culture yogurt are infrequent finds. That's the main reason I make my own. Many yogurt recipes recommend you buy fresh yogurt from the store every three or four times you make yogurt, while others say you will have better flavor if you always use your homemade starter. I find that my homemade yogurt starter works much more quickly now that it is many generations removed from the batch from the grocery store. Every source I checked on the Web said you must start your yogurt from plain, unflavored active-culture yogurt, but the only essential part of that is "active-culture." If you use flavored yogurt, you get a little artificial sweetener and flavoring in the first batch (which is easily disguised by strawberry jam or apple butter). After the first batch, the flavoring is diluted out, and the yogurt culture starts to "work" much more quickly.