How to Make Yogurt With Chemistry

How to Make Yogurt With Chemistry Yogurt is made by fermenting milk. Its high in protein, calcium, and probiotics (good bacteria). Heres how to make yogurt and a look at the chemistry of yogurt. Chemistry Yogurt forms when bacteria ferment the sugar lactose (C12H22O11) into lactic acid (C3H6O3). The lactic acid makes the milk more acidic (lower the pH), causing the proteins in milk to coagulate. The main protein in dairy milk is casein. The acidity gives yogurt its tangy flavor, while the coagulated proteins result in a thickened, creamy texture. There is no simple chemical equation for yogurt production since multiple reactions occur. Several types of bacteria can ferment lactose. Yogurt cultures may contain Lactobacillus delbrueckii subsp. bulgaricus, other Lactobacillus strains, Streptococcus thermophilus, and bifidobacteria. Recipe You can make yogurt from any type of milk. Although most yogurt is made from bovine milk (e.g., cow, sheep, goat), the fermentation process works on other types of milk, as long as they contain a sugar for the bacteria to ferment and protein that can be coagulated. Yogurt can be made from soy milk, coconut milk, and almond milk. The first time you make yogurt, you need a starter culture as a source of the bacteria. You can use ordinary store-bought yogurt with active culture or you can use freeze-dried yogurt starter. If you use a commercial yogurt starter, follow the packaging directions, since activating the culture varies depending on the product. Once you make your first batch of yogurt, you can use a couple of tablespoons of it to start future batches. While it may seem like you would want to add more active culture to a recipe, adding too much bacteria produces a sour yogurt rather than a pleasantly tangy yogurt. Ingredients   1 quart milk (any kind)1/4 to 1/2 cup non-fat dry milk (optional)2 tablespoons plain yogurt with live cultures (or you can use freeze-dried bacteria instead) Recipe Set the starter yogurt out at room temperature while you prepare the milk. This warms the yogurt so that it wont chill your recipe too much when you add it later.Heat the milk to 185 °F (85 °C). The purpose of this step is to re-pasteurize the yogurt, preventing any unwanted bacteria from growing, and to denature the proteins so that they will be able to coalesce and thicken the yogurt. The easiest way to do this is to use a double boiler or set your container of milk inside a pan of water. Heat the water to near-boiling. Dont worry- the ​​milk cant boil using this technique. If you have to heat the milk directly, stir it constantly and watch the temperature to make sure it doesnt boil or burn. If you do not have a thermometer, the milk will start to froth at 185 °F (85 °C).Once the milk reaches the temperature or starts to froth, remove it from heat and allow the milk to cool 110 °F (43 °C). One way to do this is to place the container of milk in a cold wat er bath. Otherwise, you can leave the milk on the counter and allow it to cool. Either way, stir the milk occasionally so that the temperature is uniform. Dont proceed to the next step until the temperature of the milk is below 120 °F(49 °C), but dont let the milk cool below 90 °F (32 °C). 110 °F (43 °C) is the optimal temperature. At this point, you can add nonfat dry milk. This is an optional step that helps the yogurt thicken more readily, plus it adds nutritional content to the yogurt. Its purely a matter of preference, whether you add the dry milk or not.Stir in the starter yogurt.Put the yogurt into clean, sterile containers. Containers can be sterilized by boiling them. The reason for sterilizing the containers is to prevent unwanted mold or bacteria from growing in your yogurt. Cover each container with plastic wrap or a lid.Keep the yogurt as close to 100 °F (38 °C) as possible and undisturbed, to bacterial growth. Some ovens have a proof setting that you can use. Other ideas include setting the yogurt on a heating mat (being sure to check the temperature) or placing the containers in a warm water bath. Youll have a custard-like yogurt after about 7 hours. It wont resemble store-bought yogurt because that has thickeners and additional ingredients. Your yogurt should have a yellowish or greenish liq uid on top, a creamy custard texture, and may have a cheesy odor. The thin yellowish liquid is whey. You can pour it off or mix it in, whichever you prefer. Its completely edible, though you may add fruit, flavorings, or herbs, according to your taste. If you leave the yogurt at this temperature longer than 7 hours, it will thicken and become tangier. When the yogurt is the thickness and flavor you want, refrigerate it. Homemade yogurt will keep for 1-2 weeks. You can use yogurt from this batch as a starter for the next batch. If you are going to use yogurt as a starter, use unflavored yogurt, within 5-7 days.

The Holly Tree

The Holly Tree When I built my house almost nine years ago (friggin wow), I planted holly trees on two corners of the structure, one to the left of my study window. Because I love birds, I yearned for the day the tree grew tall and thick enough for me to see its bird visitors from that window. You see, my window is fifteen feet off the ground. I planted a three-foot tree. It would be a while. But I watered the tree, did some serious pruning on it every couple of years to shape it, and made sure it was free of disease. Its a beautiful plant with its shiny, deep green leaves and occasional berries. It grew, but I could only see it when I went outside and stood next to it. Sometime during 2013, I heard a mockingbird outside being particularly loud. On occasion a bird, usually a tiny wren or house finch, or even a rare goldfinch, will perch on my window sill seeking bugs. Since I write late into the night, my window holds the only light in the cove. Being in the country, we dont do streetlights, so dark is DARK out here. The bugs flock to my window, unfortunately for me, but fortunately for the birds that gobble them up the next day. Anyway, the mockingbird song puzzled me. Sliding to my window, I listened hard for the direction. Sure enough, he perched atop the holly tree. I could see him! I could hear him. It had been so long since I tried to see the tree from my window that Id forgotten it was even there . . . except when I went outside and watered it, and pruned it. I hope you can see that the point is obvious. We plant our butts in the chair and we plant words on a page. We keep at it, writing, creating, editing, even submitting. We do it, knowing it might be a long while before its matured. Then one day, and it might be several years from when you started, you look up and there it is. Your work has grown into mature, viable, and gorgeous stories. I hear so many writers talk about waiting for the right moments to write, or getting depressed about rejection, or reading so many ridiculous blog posts that tell them how long their odds are to get published. They write in spurts. They forget writing for the summer, or the winter, or the holidays. They are forgetting to water and prune their holly tree. Even if you cannot imagine success, you keep writing. Just as we love gardening, we love writing, and we tend them religiously, just the same. Because one day, well look up, and there it will be . . . that story we always imagined, sitting there, singing to the world.