Kamis, 04 November 2010
pasteurisasi susu sederhana
After all, these products are made from growing bacteria, and if you don't kill the unwanted bacteria first, you'll be growing them, also! Milk pasteurization may sound like a scary process at first. If you're like me, the name conjures up images of pristine lab settings with complicated stainless steel equipment, tubings and mysterious instrument gauges. It turns out, though, that milk pasteurization is not complicated or scary at all. With just a basic set of the right equipment, and a little attention to detail, you can easily learn how to pasteurize milk for yourself. Heating the Milk All you need to begin is a thermometer (one that will clip onto the pot is best), and a pot large enough to hold your milk container. (A stainless steel milk bucket works very well for holding the milk for pasteurizing.) Add water to the large pot, and set your container of strained milk in the water. Clip the thermometer to the milk container so that the end of it is covered by the milk. Note: Be sure the end of the thermometer is not touching the bottom of the pot, or you will get a higher reading than is accurate for the milk. Also, if your thermometer doesn't have a clip, you can easily fashion one from a large paperclip. Heat on high, stirring the milk occasionally, until the thermometer shows the correct temperature. Always stir the milk immediately before checking the temperature, as the process of stirring will bring the warmer milk up from the bottom and usually cause the temperature reading to increase by several degrees almost immediately. Stir constantly, keeping the milk at the proper temperature for the recommended period of time. There are a variety of combinations of temperature and processing time for successfully pasteurizing milk. The most practical combinations for home milk pasteurization are: 161° Farhrenheit for 30 seconds, (some sources use 165° for 15 seconds) or 145° Fahrenheit for 30 minutes The milk must remain at or above the recommended temperature for the entire processing time. If you're planning to drink the milk, the higher temperature/shorter time period combination of milk pasteurization is more convenient. It's much quicker and easier to monitor the milk for thirty seconds than for thirty minutes! However, if you're planning to try Goat Cheese Making with your milk, the lower temperature method is recommended, as it will allow some of the beneficial enzymes and bacteria to survive that will enhance the flavor of the cheese. Cooling the Milk When the milk has processed for the required time, remove it from the water and place in a sink or pan of cold water. In a few minutes, when the water becomes warm, exchange it for cold, and also add ice to the water. Stir the milk often to increase the cooling effect. You can continue like this, exchanging the ice water and stirring the milk until it reaches the proper holding temperature of 40° Fahrenheit. The longer the milk takes to cool, the more off-taste it will have. Milk that is not cooled quickly enough usually has a "nutty" or "vanilla-like" flavor. It can still be used; it is just not as appealing to drink plain. If this happens to your milk, you will need to increase the amount of ice, decrease the time between water changes, and be sure to stir the milk continuously. OR...you can try my "secret" weapon: an electric ice cream freezer. Use the freezer just as if you were making ice cream, layering the ice and rock salt around the outside of the can. Then pour in the milk, close the lid, adjust the motor and turn it on. Monitor the need for additional ice and salt, and check the temperature at 10 minutes, then at 5 minute intervals. This method has always cooled my pasteurized milk to 40° Fahrenheit in less than 20 minutes, which is Grade A standard. It is so much faster than the ice water method, that my first two batches started to freeze before I was aware the milk was already cold! And, the difference in the taste of the milk is extraordinary. Alternatives If you'll be pasteurizing milk on a regular basis, especially daily, you may want to invest in some equipment to help streamline the process. One option is a home milk pasteurizer, such as the SafGard Pres-Vac. This electric pasteurizer performs automatic, pressure-sealed pasteurization of up to two gallons of milk at a time. Then, a hose connects to the faucet for vacuum- sealed cooling of the milk. Home pasteurizers are not inexpensive-- expect to spend over $300 for one. But, they do the job quicker and more precisely than other methods, and require almost no attention during the process. If you expect to be handling goat milk for some time, you may want to make the investment. Another option is to use a Weck canner-pasteurizer. This is the method that I use. The Weck is only slightly less expensive than a home pasteurizer, but it has the advantage of being multi- functional. It is basically a huge, electric stainless steel pot with a lid. You pasteurize milk in the Weck the same way you do with a pot on the stove. Add water to the Weck, turn it on, then set a milk bucket or tote inside. A 2-gallon milk tote will fit easily inside it. Since the lid to the Weck fits right over the tote, the milk heats quickly. You can also use it for canning, or for cooking anything that requires a big pot-- apples for applesauce, boiled peanuts, or soups or stews for large gatherings. If I had to choose only one kitchen appliance to keep, it would be my Weck! Whichever method you choose, a little attention to detail will produce safe, great-tasting, pasteurized milk at home. For more information on obtaining equipment for processing your milk, see Milk Processing Equipment. Now that you have freshly pasteurized goat milk, why not consider learning Goat Cheese Making or making other goat milk products with it?