重新加热的外卖食品安全吗？

BBC双语阅读(2016年5月9日)

辛苦忙碌一天后，人们常常会把当天的外卖重新加热一下当晚餐吃。这听起来不错，但是其中的风险也不小。英国每年有大约100万人食物中毒。其实，只需采取几个简单步骤就能安然无虞。

电视节目《相信我，我是医生》（Trust Me I’m a Doctor）的主持人迈克·莫斯利（Michael Mosley）在节目中使用热成像摄像机分析重新加热的外卖食品是否安全。

莫斯利介绍说，必须把食品加热到摄氏82度才能确保杀灭所有病菌。

广受欢迎的外卖米饭容易沾染一种名为蜡样芽胞杆菌的病菌

在食品加热过程中，尽管食品的外表面冒出蒸汽，但是内部却可能没有达到高温状态——从而使一部分细菌有了藏身之所。因此，在加热过程中要不断搅拌，从而保证食品受热均匀。

即便采取了上述步骤，一份食品也绝不可加热超过一次。食品每次冷却过程都给病菌繁殖创造了良好条件，等下次用燃气炉或者微波炉加热时就更加难以彻底杀灭。

对于一种广受欢迎的外卖食品——米饭，这一点尤其显著。米饭容易沾染一种名为蜡样芽胞杆菌（Bacillus cereus）的病菌，这种病菌会在食品内部生成毒素，造成腹泻和呕吐。不幸的是，这种毒素在高温下不会分解。即使把食品加热到能够杀死病菌的温度，也无法去除其中的毒素，食用被毒素污染的食品后，会很快出现中毒症状。

要想长时间保存外卖食品，就必须把在病菌开始大量分泌毒素前，即在米饭煮好后1小时内将其迅速冷却并冷藏。否则，你就是在“玩一场危险的俄罗斯轮盘赌”，莫斯利说。

（责编：友义）

This is what you need to know about reheating takeaways

9 May 2024

Reheating a takeaway (or if you’re American, take-out) may seem like a good idea at the end of a hard day – but many of us have learnt that there can be a heavy price to pay. Around one million people in the UK suffer food poisoning each year, and it’s often because we have failed to take a few simple steps.

In the video below, Michael Mosley of the TV programme Trust Me I’m a Doctor uses a thermal camera to analyse whether reheated takeaway food is safe or not:

As Mosley explains, the trick is to heat the food until it is 82C (176F) throughout to be sure that you can kill any harmful bacteria.

That’s easier said than done: while the outside may seem to be steaming, the inside could have remained cooler – hosting a pocket of living bacteria. It’s for this reason that it’s important to stir the dish so that all the food is heated evenly.

One particular takeaway favourite can host spores of a nasty bug called Bacillus cereus

Even after having followed these steps, you shouldn’t reheat a meal more than once. Each time it cools down, you offer more opportunities for the harmful bacteria to multiply, making it harder to kill them all off the next time you stick them in the oven or microwave.

This is particularly true for one particular takeaway favourite – rice – which can host spores of a nasty bug called Bacillus cereus. When left in food, the bacteria produces toxins that trigger diarrhoea and vomiting. Unfortunately, these toxins are “heat stable” meaning that even if you heat the rice to the point of killing all the bacteria, the toxins will survive – and you’ll soon notice the effects of ingesting those poisons.

If you do want to save your leftovers, you should cool the rice quickly – before the bacteria can start churning out those toxins – and refrigerate within an hour of cooking. Otherwise you really are “playing Russian roulette with your guts”, says Mosley.