科学实验室：自制雪糕乐无穷

As summer comes rolling in， you might be thinking more and more about cooler sweets to eat， namely[也就是] ice cream. Or maybe you think about ice cream all the time， no matter what the temperature is. Regardless[不管]， ice cream is definitely one of the most delicious treats[宴饗] you can have， but did you know you dont only have to buy it at the store？ You can make it yourself！

Water has three states： solid[固体]， liquid and gas. Water changes into its solid state when it reaches 0 °C， but if there is Sodium Chloride[氯化钠] （NaCl）， otherwise known as salt， then that temperature drops. Thats because salt lowers waters freezing point[凝固点]. Have you ever noticed how when the sidewalk is icy they put salt on it to melt the ice and make it safer for walking？ Thats the same principle[原理]. The salt they put on the sidewalk mixes with the ice and because its freezing point is lower than the temperature of the unsalted ice， the sidewalk melts.

When youre making ice cream the lower temperature of the ice and salt mixture[混合物]， which surrounds the cream and sugar mixture， is cold enough to change the state of the cream from a liquid to a solid. So lets get started！

随着夏天的热浪扑面而来，你也许会愈发渴望吃点更凉快的甜食，也就是雪糕。又或者不管气温高低，你一年到头都惦记着雪糕呢。不管怎样，雪糕绝对是最可口馋人的美食之一，但你知道雪糕并不是只能在商店买到吗？你完全可以自己动手做喔！

水有三种形态：固态、液态和气态。水达到零度就会转化成固态，但如果有氯化钠（NaCl）——也就是我们常说的盐参与反应，水的结冰温度就会变低。这是因为盐会降低水的凝固点。你留意到了吗？每当人行道结冰的时候，人们总会在路上撒盐，将冰块融化，才能安全通行。那也是出于同样的原理。撒在人行道上的盐会与冰融合，由于其凝固点比没撒盐的冰块要低，人行道（上的结冰）就会融化。

在你制作雪糕的时候，奶糖混合物周围的冰盐混合物温度更低，足以让液态的奶油凝结成固态。让我们这就来试试吧！

Materials 材料

1/2 cup milk

1/2 cup whipping cream[生奶油] or heavy cream[多脂奶油]

1/4 cup white sugar

1/4 teaspoon vanilla extract[香草精]

1/2 to 3/4 cup table salt[精制食盐]

2 cups ice

quart Ziploc bag[封口袋]

gallon Ziploc bag

Thermometer[温度计]

Measuring cups and spoons

Bowls， cups， spoons or cones[锥形蛋卷筒] to serve your ice cream treat

半杯牛奶

半杯生奶油或多脂奶油

1/4杯白糖

1/4茶匙香草精

1/2到3/4杯精制食盐

两杯冰块

夸脱封口袋

加仑封口袋

温度计

量杯和量匙

用来享受美味雪糕的大碗、杯子、勺子或者甜筒等

Procedure 步骤

1. Add 1/4 cup sugar， 1/2 cup milk， 1/2 cup cream， and 1/4 teaspoon vanilla to the quart Ziploc bag. Zip that bag up so nothing leaks[泄露]！

2. Put the 2 cups of ice into the gallon Ziploc bag.

3. Use the thermometer to measure the temperature of the ice in the gallon bag. Make sure to record this number so you can remember.

4. Add 1/2 to 3/4 cup salt to the gallon Ziploc bag of ice.

5. Place the sealed[密封的] quart bag inside the gallon bag of ice and salt. Seal the gallon bag securely[牢固地].

6. Rock the gallon bag from side to side. Hold it at the seal so that the cold ice doesnt freeze your hands instead of your ice cream. You can also use gloves[手套] or a cloth to protect your hands， just remember it will be colder than 0 °C！

7. Continue to rock the bag for 10-15 minutes or until the contents of the quart bag have solidified[凝固]， or until you cant wait for ice cream anymore.

8. Open the gallon bag and use the thermometer to measure and record the temperature of the ice and salt mixture. Notice how much colder it is than the ice on its own.

9. In bowls or cones serve and most importantly enjoy your homemade[自制的] ice cream！

1. 將1/4杯糖、半杯牛奶、半杯奶油和1/4杯香草精加入夸脱封口袋。袋子的封口要封好，可别漏出来哦！

2. 将两杯冰块倒入加仑封口袋中。

3. 用温度计测量一下加仑袋里的冰块温度，将数值记录下来，以防忘记。

4. 将1/2到3/4杯盐倒入装有冰块的加仑袋中。

5. 将密封的夸脱袋放入装有冰块和盐的加仑袋中，确保加仑袋密封好了。

6. 左右摇晃加仑袋。手抓封口，以免低温冰块在雪糕做好之前就将你的手给冻伤了。你也可以用手套或者一块布保护好手部，要记住这温度是在零度以下哦！

7. 继续摇晃10到15分钟，或者等到夸脱袋里面的东西已经凝固，又或者到你已经迫不及待要吃雪糕才停止。

8. 打开加仑袋，用温度计测量并记录袋中的冰盐混合物温度。注意对照这个温度和冰块本身的温度相差多少度。

9. 装到碗里或者甜筒里，最重要的是尽情享受你的自制雪糕！

Toppings 浇头

Theres always the possibility to add all different types of toppings： chocolate sauce， sprinkles[糖屑]， caramel[焦糖]， strawberries， chocolate chips！ Feel free to add these ingredients[作料] to the quart bag before you mix everything， but know that your mixture will turn to ice cream much faster if you hold these special treats and add them as toppings.

雪糕上面总是可以浇上各种各样的配料：巧克力酱、糖粒、焦糖、草莓，甚至巧克力棒！你也可以在混合之前往夸脱袋里随意加入这些东西，但你得知道，如果将这些特殊配料留到最后作为雪顶浇头，你的混合物凝固成雪糕的速度会更快喔。

Ice Cream Maker 雪糕机

This is a very easy way to make some delicious ice cream！ If you are interested in making your own homemade ice cream all the time， you may want to look into an actual ice cream maker. It still uses the ice and salt mixture to freeze the cream， it just provides an easier and higher volume[量] way to make ice cream at home.

这能让你轻而易举地制作出美味的雪糕！如果喜欢随时自制雪糕，你也许该考虑买台真正的雪糕机了。雪糕机也是靠冰盐混合物将奶油冻结，不过它能为你在家里自制雪糕提供一种容量更大的便捷方式。

你知道吗？

夸脱（quart）是容量单位，主要在英国、美国及爱尔兰使用。1夸脱于英国和美国代表的是不同的容量，而美国更有两种夸脱：干量夸脱及湿量夸脱。

英制：1夸脱= 1136.5225 毫升

美制：1干量夸脱= 1101.220 毫升

1湿量夸脱= 946.352946 毫升

而1加仑（gallon）=4夸脱，1品脱（pint）=1/2夸脱。