Food: Science Picture Challenge #2 The science of toasted marshmallows, my favourite food| 食物：科學照片挑戰 #2 我最喜愛的食物，烘棉花糖的科學

The left one is a marshmallow toast toasted in an oven and and the other one is an untoasted marshmallow toast. What are the differences between them? (Please ignore the toast, the focus is on the marshmallows :) )

1- Toasted marshmallows are larger.

Marshmallows mainly consist of whipped sugar syrup and gelatin. When heated, the air molecules move faster and the spaces between molecules are larger, aka air expands. About 40-60% of marshmallows is air, they are trapped by stretchy gelatin, which allow marshmallow to expand, so toasted marshmallow turned larger.

2- The surfaces of marshmallows turned brown and hardened.

One of the main component of marshmallow is sugar. When sugar is heated in high heat (Over 160° C), a complex process called caramelization occurs, three groups of polymers: caramelans (C24H36O18), caramelens (C36H50O25), and caramelins (C125H188O80) are produced, which make it brown, hard and tasty (the toasted taste) :p

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這是一張烘過和沒有烘過的棉花糖多士的照片。他們有甚麼分別呢？(請無視下面的多士，重點是棉花糖:) )

1- 烘過的棉花糖比較大

棉花糖是用打發的糖漿和明膠做的。當空氣遇熱，份子移動速度加快，距離增加，就是所謂的空氣遇熱膨脹。棉花糖的40-50% 是空氣。有彈性的明膠把空氣困住，空氣膨脹把明膠撐開，棉花糖就變大了。

2- 棉花糖的表面變咖啡色和硬

糖是棉花糖的主要成份。在高温(160° C以上)，糖會產生複雜的焦糖化反應，過程會產生三種聚合物，聚焦糖(C24H36O18), 亞焦糖(C36H50O25), 焦糖素(C125H188O80)。令食物變咖啡色，變硬，美味(有焦香) :p。

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Reference 參考資料 :
https://www.stevespanglerscience.com/lab/experiments/marshmallow-masher/ https://www.education.com/activity/article/Exploding_Marshmallows/
https://www.scienceabc.com/eyeopeners/why-do-marshmallows-blow-up-in-microwave-oven.html?isamp=1
https://en.m.wikipedia.org/wiki/Caramelization