This steaming process is why so many deep-fried foods are battered (这种蒸制的作用就是为什么很多油炸食物表面都有一层面糊)– onion rings, fish, corn dogs, Oreos, and Mars bars, to name just a very few.The shell must form instantaneously, or the vapour will continue to seep[渗出] out, dampening the outer layer and desiccating[使脱水] the interior. At the same time, oil will seep in, making the food leaden[呆滞的]and soggy[湿的]. Most things can't form a solid shell fast enough. A starchy[淀粉的] batter can, though, and the more the starch molecules latch[名词意思是门闩] onto each other, in a process called cross-linking, the more water is expelled and the crunchier the outcome. What’s more, starch has the potential to undergo the chemical reactions that cause browning and caramelising[焦糖化] – key to the sweet notes in a good fried food.
著有《现代主义烹饪法》（”Modernist Cuisine”）的微软前技术总监内森·蒙弗德（Nathan Myhrvold）曾历经无数困难险阻就是为了创作出叫做“超音速炸薯条”的食谱。
Nathan Myhrvold, former Microsoft CTO and author of the Modernist Cuisine cookbook has gone several levels of difficulty further with his recipe for “ultrasonic French fries”. It’s not exactly something you can try at home, but the result is apparently a “hugely satisfying crunch when you bite through the exterior” before yielding to “a centre of incredibly smooth mashed-potato consistency”, and a process he says could be automated by a food manufacturer.
The recipe vacuum seals chips in 2% brine before hitting them with ultrasound waves from the same device dentists and jewellers use, which cracks and blisters each chip with tiny bubbles and fissures. Next, the chips are vacuum-dried, to adjust the water content of the exterior, and then are briefly blanched in oil at 170C (340F) to tighten the network of starch molecules. After cooling, they are fried for a few minutes in hot oil at 190C (375F). The idea here is that the water turns to steam inside each minuscule bubble on a chip’s surface, forcing the bubbles to puff up.
What’s more, starch has the potential to undergo the chemical reactions that cause browning and caramelising[焦糖化] – key to the sweet notes in a good fried food.