Stroll through the frozen foods section of the supermarket andyou'll find frozen corn, peas, and beans.
你在闲逛超市的冷冻食品区的时候，会看到有冷冻玉米、冷冻豌豆和冷冻大豆2[qCP*9e.3lUgoQS.M。
A Moment of Science wonders, why isn't there any frozenlettuce?
《科学一刻》栏目很好奇，为什么看不到冷冻莴苣呢？
Freezing is a relatively easy and convenient way to preserve many vegetables because it slowsdown or destroys the bacteria and enzymes that cause spoilage.
冷冻是储藏很多蔬菜的一种相对简单、便捷的方法，因为它会减慢导致食物变质的细菌和酶的增长或者杀死它们Wg7|Tx7rK*L。
But, the freezing process itself can cause changes in food that can spoil the appetite.
但是，冷冻过程本身就会改变食物，从而影响食物的口感1XrwG*k3#Mxq4r;fNx。
During freezing, the water in every cell of the vegetable freezes and forms ice crystals.
在冷冻过程中，蔬菜的每个细胞中的水都会结冰E4oT*VTOmdS5yv_@。
As we knowfrom our ice cube trays, water expands in volume when it is frozen.
从制冰格我们可以知道，水在冻冰时体积会膨胀d5wTE9F~I0G)。
In frozen vegetables, the icecrystals expand and damage the wall that surrounds each cell.
对于冷冻蔬菜而言，冰晶膨胀会破坏蔬菜细胞的细胞壁|Y)cD(I~SR-2wX%ykxFl。

When the cell walls are damaged, the vegetable's structure is weakened, and its texture becomes softer.
细胞壁受损时，蔬菜的结构就会变得不稳定，质地就会变软IBoV5Tf!wFOJG_x*IERi。
Some vegetables, like corn and peas, have a lot of starch in them but very little water.
像玉米和豌豆这样的蔬菜含有大量的淀粉但含水量却不高，
So they maintain their structure in spite of the cell damage.
因此就算是细胞壁受损，它们的结构也不会发生改变Xcifub)a@W,k=!,K#2。
But, other vegetables, like lettuce and cucumbers, have a lot of water in them and more delicate cell walls.
但是像莴苣和黄瓜这类蔬菜本身水分较多，且细胞壁也更脆弱，
The ice crystals damage thesevegetables so badly that they really can't be frozen without turning into mush.
所以冰晶会对这类蔬菜造成很严重的影响，所以在没被捣碎的情况下最好不要将它们冷冻起来u6@Fn[iy-vTRyWO。
Ice crystals can reduce almost any vegetable to mush if poor freezing technique is used.
如果冷冻方法运用不当，冰晶几乎可以把任何蔬菜都变得软绵绵uRbmSaBYv*1+o。
Slowfreezing creates larger ice crystals than fast freezing and causes more damage.
慢冷冻所形成的冰晶要比快冷冻大，因而造成的损害也更多7sDVrHbY5aG,VQW。
Repeated thawing and freezing also creates larger crystals and can turn fresh,crunchy vegetables into unappetizing,mushy goo.
反复的解冻和冷冻也会形成较大的冰晶，能够把新鲜的蔬菜变得黏黏糊糊，让人没了胃口DNzvHuEpyH46N+r+。
Oddly enough, good freezing technique means boiling the raw vegetables for twenty seconds before quickly cooling and then freezing.
说来也奇怪，良好的冷冻方法竟然要把生蔬菜先煮沸20秒，然后快速冷却，最后再冷冻起来n4URY;4s@5k9nQ(。
The brief boiling makes the cell walls slightly more elastic.
短暂的煮沸可以使细胞壁变得更加有弹性8&z=F_ZOTQOX@HTniSD。