"Play, that's what we're talking about today."

Except for the first two girls, the new chemistry teacher never interrupted the others' speeches, but quietly listened to the other five girls introduce themselves and began today's lesson. However, his first sentence still fully mobilized the enthusiasm of the girls.

"What to play? It's something that you girls like very much. You can find it in a lot of food, and you'll have it in your lunch today, in chocolate, in puffs, in jelly, in preserves, and of course, in your favorite ice cream. Can you guess what this is? ”

"Cream, milk, flour, chocolate, cocoa, salt, oriental fish, ......"

The seven girls gave more than a dozen answers, and in the end, the correct answer was finally said.

"That's right, sugar, we're going to play sugar today!"

He walked over to the blackboard. Soon the name William Cowie was erased, and the word "Sugar" appeared in the center of the top of the blackboard.

Then he walked to the far left of the blackboard and wrote the words "212~225°F 60%-70%" on the top, and then moved to the right to write "230°F 85%". While writing on the board, he said:

"As a source of sweetness, sugar has other important roles besides sweetness. It has good hydrophilicity, and it can be used in the process of making pastries to increase softness, and make the finished product have a good taste and flavor while shaping; When making fermented products, it can provide energy for yeast; When making ice cream, it helps to lower the freezing point; In the preservation of food, it can also play a role in preventing spoilage and prolonging the storage time of food. ”

In an instant, under "Sugar" on the blackboard, there were six more columns, from left to right: "212~225°F 60%-70%", "230°F 85%", "237~266°F 87%-98%", "275~302°F 99%-100%", "311~329°F", "356°F".

He turned to the girls, turned to the girls and said, "In addition to these effects, sugar has a wonderful property that can transform into different forms at different temperatures and concentrations. The sugar melts in water and heats it to become a syrup, and as the water evaporates as it continues to be heated, the concentration of the syrup gradually increases, and its boiling point changes accordingly——"

Speaking of this, he paused and asked, "The terms evaporation and boiling point should have been taught in the seventh-grade lattice physics, and I think the words I said should not be difficult for everyone, right?" ”

The girls nodded.

"Then I'll continue to talk, if you don't understand, you can ask questions at any time." Seeing the girls nodding, he continued, "According to the different heating temperature and concentration, if you roughly divide it, the temperature is from 212 degrees Fahrenheit to 356 degrees, and the concentration is from 60% to 100%, and there will be a total of six forms of sugar. With that, he took two steps back, came to the far left of the blackboard, pointed to the first column of numbers, and said: "212 degrees Fahrenheit to 225 degrees, the concentration is between 60 and 70 percent, and this is the first form of sugar, which can be called lamellar syrup." What is lamellar syrup? That is, if the syrup is glued with a spoon after cooling, a thin layer of sugar will form on the surface of the spoon. ”

At this time, a few girls took out paper and pens to prepare for the record, but there was no desk in front of the chair, and they hesitated for a while.

The voice in front of the blackboard paused, as if noticing what was happening behind him.

"You don't need to take notes, all the lecture content is mimeographed into lecture notes, which are on the table at the back, and will be distributed to everyone when the experiment is officially done."

Everyone looked back, and sure enough, they found that the last Eight Immortals Table had a stack of papers more than the other tables.

"I've always thought that listening to lectures is story-based, but when it's on paper, it becomes intellectual," the voice in front of the blackboard continued, "and rote learning is far less efficient than learning from stories." The reason why we don't send the handouts to everyone in advance is so that everyone can immerse themselves in the process of listening to the lecture without distraction. In a moment, you will find that reading the lecture notes and trying to remember what I have said can help you remember and improve your understanding. ”

"That's why our chemistry class is all about playing. I think that instead of choosing experimental topics that are only purposeful and not interesting, it is better to have fun and gain knowledge at the same time. For example, today, are we playing with sugar? No, we're playing with temperature and concentration, which are two of the most critical elements that are indispensable for all chemical reactions. ”

"Alright, let's get down to business." He took a step forward to the second column of numbers, "The second form is filamentous syrup, and when we continue to heat the syrup to 230 degrees Fahrenheit, when the syrup concentration is 85%, then we can use our fingers to stick a little syrup to pull out about an inch and a half long silk of sugar. ”

"What is filamentous syrup suitable for? The candied fruit and jelly that everyone likes to eat are actually filamentous syrup. ”

"The third form, I call it globular syrup." He came to the third column of numbers, "But this form is divided into three states. ”

He picked up the chalk and added new items below the numbers in the third column: "237~243°F 87%-95%", "244~248°F 96%-97%", and "249~266°F 98%".

"The first state, the soft globule state." "At 237 to 243 degrees Fahrenheit, at a concentration between 87 and 95 percent, a little boiling syrup in ice water will form a soft ball." You can pinch it when the time comes, and you will find that it is very soft, but it is also easy to deform. ”

"The second state is the elastic ball state. 244 to 248 degrees Fahrenheit, at which point the concentration is 96 to 97 percent. Compared to soft balls, although the balls are still soft, they are elastic and can be rubbed between fingers and turned without deforming. ”

"The third state is the rigid ball state. 249 to 266 degrees Fahrenheit at a concentration of 98%. At this point, the ball has become hard and does not deform. ”

"What's the use of globular syrup? I'll give you three examples, first, the soft balls, the sugar crust wrapped around the puffs; secondly, elastic balls, almond stuffing for macarons; Finally, rigid balls, toffee. ”

"Is it that delicious? I saw someone swallowing, I remember you just had lunch. ”

The girls laughed as they ate.

"By the time the syrup continues to heat to 275 degrees Fahrenheit, the concentration has reached 99 percent, and the syrup is in a broken state."

He walked to the fourth column and added "275~284°F 99%" and "293~302°F 100%" below with chalk.

"At 275 to 284 degrees Fahrenheit, in a soft crumbled state, the boiling syrup is poured into ice water, and the formation is no longer a ball but an irregularly shaped soft crisp, which sticks to the mouth. This syrup is the raw material used to make soft nougat. ”

"293 degrees Fahrenheit to 302 degrees Fahrenheit, hard crushing, at this time the sugar solution concentration is 100%, and the irregular chips formed by putting it in ice water become hard and no longer stick to the teeth. This syrup can be used to make hard nougat and hard caramel. ”

Below the fifth column, he added three new sub-items: 311°F, 320°F, and 329°F.

"At 311 degrees Fahrenheit, the syrup goes into caramel. At this time, the syrup is pale yellow and is called the pale yellow caramel state. ”

"When heated to 320 degrees Fahrenheit, the syrup will have a straw-like golden color, called a golden caramel state."

"Finally, when the temperature reaches 329 degrees Fahrenheit, the syrup has melted to a yellow-brown color, which is now a brownish caramel-like state."

"What can you do with caramel? Have you ever eaten a cream cake from the welfare department store? Is it dotted with swans, flowers, etc., made of sugar? ”

The girls all nodded.

"These are drawn and blown with yellowish caramel. As for brown caramel, it is tougher and can be rolled out into various shapes with a rolling pin, while gold caramel is more viscous and can be used as a glue between small snacks. ”

"Alright, here's the last dark brown caramel state," he walked to the front of the sixth column, "and the temperature is above 356 degrees Fahrenheit, and the syrup is completely caramelized and darkened. In fact, everyone often eats syrup in this state, and the dark brown color on the bottom of the pudding is actually dark brown caramel. ”

"That's all for the theoretical part of today's chemistry class, do you have any questions?" He walked back to the podium.

"Yes! What is the use of the first form? ”

"Yes, what is the use of lamellar syrup?"

Several girls screamed.

"It seems that everyone listened very carefully, but I specially omitted it because I was afraid of hooking out your gluttonous worms-"

The bell rang out very inopportunely, and the girls were surprised how this class passed so quickly, only to see the gentleman in front of the podium smile slyly: "It's so fast, it's time for the end of class, anyway, the next class is still mine, let's wait until the next class." ”

The girls all shook their heads.

"Okay, look at everyone's unfinished looks, why don't we rest and start experimenting directly?"

"Okay, but first tell us what lamellar syrup is for." The girls shouted.

"Laminated syrup is ideal for fruit gummies, pralines and jams. What do you think? Is it to everyone's taste? ”

"Together!" The girls laughed in unison.

"Okay, then I'll briefly explain the steps of the experiment first, and then everyone will rest for a while, and let's start the experiment directly."

"The experiment is actually very simple, as long as the temperature is controlled, the whole process is actually the process of continuous evaporation of water in the syrup, as the concentration of the syrup gradually increases, its boiling point will also change accordingly, reaching a certain temperature, it means reaching a certain concentration. So just control the temperature. ”

"Okay, let's talk about it first, if you feel tired, you can go out to breathe, if you need to solve the problem, hurry up to solve the problem, and if you want to experiment immediately, you can start it."