Yeast 酵母

As mentioned before, we will elaborate on the major ingredients in bread-making. Today we want to introduce to you the first on the list: yeast.

Yeasts are organisms that feed on sugar/starch, and gives off carbon dioxide, alcohol, and water. They work optimally at warmer environments with moisture and oxygen present. There are various kinds of yeast, but the two major kinds of yeast you can find in almost any supermarkets are a) active dry yeast, and b) instant dry yeast. These two kinds of yeast are both dried, milled into granules, and packaged sometimes in sachets (each holds approximately 7 grams which is equivalent to 2 1/4 teaspoons), bags, cans, or plastic containers. Dried yeasts stay dormant until lukewarm water is added. Active dry yeast has a larger granule, and needs to be dissolved in water before using, while instant dry yeast is finer, and can be incorporated straight into other ingredients. These can be used interchangeably, but if the yeast has been sitting on your shelf or your fridge for some time, do test out the viability of the yeast before incorporating it in other ingredients. You can do that by dissolving a small amount of yeast and a sprinkle of sugar in lukewarm water. The temperature of water matters as yeasts are sensitive to water temperature. You will be killing the yeast if the water is too hot. But if it’s too cold the yeast will not be activated. The ideal temperature is roughly 110°F, that is 43°C. For your reference, our body temperature is at 37.4°C, therefore if you do not own a food thermometer, you can test the water by immersing your fingers into a bowl of lukewarm water. If your fingers can stand the heat for more than 10 seconds, the temperature is about right. Give the yeast 5 minutes to work. If it puffs and foams and gives off a yeasty smell, the yeast is good to go. If nothing happens, discard the yeast and buy a new batch. To make a loaf or two of bread, a sachet of yeast is sufficient. When yeast is mixed with flour, salt, warm water, it is kneaded until a smooth dough is formed. The dough is usually left to sit covered on the counter or in a bowl until it has doubled in size. The dough is then shaped into loaves and left to rise again until it has doubled again. What happens during the rise is that yeasts digested the sugar from the flour and form pockets of carbon dioxide that gets trapped by the gluten structure generated by kneading wheat flour into a dough. When the dough is baked, the pockets are set, producing a soft and spongy structure throughout. The time for each rise depends on the humidity and temperature, but on average each rise takes approximately 45 minutes to an hour. But during this time you do not have to stand there and observe the yeast, you are free to do other chores while the yeasts are working its magic.

http://www.thekitchn.com/whats-the-difference-between-active-dry-yeast-and-instant-yeast-54252

酵母是菌,與菇算是同類,同類以孢子繁植,亦帶有曖昩的氣味。我們造麵包的,與酵母的關係不能分割,就似是陽光與空氣。發酵這個過程很有趣,天時地利人和要配合,過程急不來,沒有100%的必勝步驟,很多時候亦憑厨師的經驗補救,看你有多了解手上的麵糰,細心觀察酵母的變化,還記得有一個寒冷的日子,本來要為友人造個麵包,因為厨房的溫度太冷麵糰發不起,我唯有將麵糰抱在大腿上,對著電腦邊工作邊告訴麵糰:「請您快點快高長大,很多人在等著與您見面呢。」就用著體溫讓麵糰發酵大概一個小時,麵糰或者感受到我的愛,看來飽飽滿滿的特別可愛。不論工作或興趣,很多事情都是經一事長一智,很多食譜都只能作為參考,臨場應急mode還是要啟動著的。
一般到巿場都可以輕易買到這兩種酵母,活性乾酵母和即溶酵母,(當然有時間的話亦可以自己培養酵母啦)乾酵母要放在溫水5-10分鐘才混進麵糰裡,好處是可以確保酵母健康沒有死去。即溶酵母就如即溶咖啡般即開即用,直接揉到麵糰已搞定。

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