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How do they know how long we should cook it?
April 15, 2014 10:40 AM   Subscribe

When the good folks at Nestle USA (Lean Cuisine) and ConAgra Foods (Health Choice) package the meals that wind up in our microwaves, how do they know how long we should cook them? I assume it has something to do with volume and density of the food. What else? And for those of us who like to think about such things: How come you cook some of them all the way through, but others have to be stirred before being reinserted for a second blaze of rays? And how come you cut that slit over the vegetables in some, but not others? And the dessert is pretty much always uncovered. Why is that? Counting on you, MeFites.
posted by John Borrowman to Food & Drink (9 answers total) 7 users marked this as a favorite
I imagine that the people who make frozen meals do a ton of testing before boxart is printed.
posted by royalsong at 10:48 AM on April 15 [11 favorites]

I recommend the Handbook of Microwave Technology for Food Application. It's kind of expensive, but you can browse it on Amazon and Google Books.
posted by jedicus at 10:48 AM on April 15 [1 favorite]

A lot of it is a little hand-wavey since different wattages of ovens will heat at slightly different rates.

On stirring: Microwaves are supposed to heat "everywhere at once. However, salt in foods can affect how much microwave energy gets to different parts of the food.
While protein, fat, and starch molecules also absorb microwave energy to a lesser degree, the presence of salt in foods can have a large influence on microwave heating. "Salt molecules tend to break apart in the presence of water," notes Anantheswaran. The sodium and chlorine ions create heat by colliding in the rapidly oscillating electromagnetic field, leaving less microwave energy available to heat the center of the food.
Additionally foods in microwaves still cook from the outside in, just more uniformly than if they were in a conventional oven.
Once you realize that energy is not passing through water, but being absorbed by it, you are onto something. For, every centimeter of moist food that the microwaves contact, there is less energy for the next centimeter. The energy doesn't go very far at all before it's all absorbed. Only the very outer layers of the food actually get heated by the interaction with the microwaves. The rest of the cooking is actually due to heat conduction from the outside to the inside.
posted by jessamyn at 10:51 AM on April 15 [4 favorites]

They know all that via extensive testing in the design and development phase. Stirring is for food that is prone to hot spots, slits are to release steam for items that don't need so much steaming (or for food that steams so much it's determined to be a safety risk). Items that aren't covered are meant to lose significant moisture in the cooking process.

A huge amount of money goes into testing this stuff in multiple types of microwaves under various conditions. Food research and development is really fascinating if you're into that sort of thing.
posted by Lyn Never at 10:54 AM on April 15 [1 favorite]

I'd also suggest reading MICROWAVE INSTRUCTIONS FOR PREPARED BUT NOT READY-TO-EAT FOODS – IT’S JUST NOT WORTH THE RISK (sorry about all-caps) for a discussion of microwaving and prepared foods from a professor at Michigan State University mostly discussing microwaveable products that have raw meat materials in them.
posted by jessamyn at 10:54 AM on April 15 [3 favorites]

These companies spend millions in test kitchens. In fact the variety of microwave wattages etc actually is part of the weird mix of slitted plastic and cover or uncover etc etc etc.
posted by chasles at 10:56 AM on April 15 [1 favorite]

The stirring is critical for stuff that has a sauce. If you've ever forgotten to stir a microwave meal that includes some amount of sauce, or not stirred it enough, you end up with a hunk of still-frozen sauce in the middle, with a bunch of crispy and burnt sauce on the edges. You stir to evenly distribute the sauce and avoid that. Compare to a microwave meal that includes sauce, but isn't frozen, like Trader Joe's non-frozen ready to eat pasta dishes. There's no instruction to stir mid-cooking because the sauce isn't frozen in one chunk in the middle, and at most you just have to shake it around a little to get more even sauce distribution.

And not specifically about frozen meals, but here's an interview with a former professional frozen food taster that gives some insight into how frozen food is developed and tested.
posted by yasaman at 11:27 AM on April 15

Re method of microwaving various prepackaged foods: Different zap for different crap. Just follow the procedure written on the package in English, French, Spanish, and sometimes Asian ideographs that I cannot begin to translate.
posted by Cranberry at 1:19 PM on April 15 [1 favorite]

Like all things cooking, start backwards from the final state and make your way to the beginning state.

In this case, start at a prepared meal served at probably 165-185 degrees F. I don't know what the desired temperature is for these at completion, but likely given that this is the guidelines for restaurants - its likely the same for these frozen meals. Now, consider the components, the texture, and the difference that all these things need to be. You don't have to build all these things together. I can pre-cook a sauce, I can pre-cook a piece of meat, I can pre-cook a few vegetables. Most importantly, i can immediately reduce all these items from their cooked temperature to cold in as short a time span as possible. This part I can't do. The point though is, I am stopping the cooking at a very specific time for each component. So now, I know that I can

Now, there are a few other things that need to be understood in order to perfect the next part, the fat content, the sugar content, and the salt content. Each of these things needs to be evenly distributed in its perspective component and effectively used to transport the heat consistently. This is one of the reasons so much of the meat that is in these is processed to the point where it is WYNGS instead of wings: truthfully, if you want to make a instant dinner WYNG meat is likely a more consistent 6-sigma approved final product. With lean meats, with 'real' chicken - they'll brine and inject the chicken with enough sodium to make sure that the heat transfers quickly and appropriately.

So after you know what the final meal that you are making is, and after you've regulated the salt sugar and fat content to the appropriate levels for the desired final cook time, you've pretty much made your TV dinner. Now you put in your starches, you put in your desert, you put your veggies in place, you drop your meat down, and you pour the sauce over the meat. None of these things needs to be their final consistency - they need to be the consistency necessary for 7(?) minutes left from complete. And you are beholden to the slowest cook time element - meaning that if the chicken needs to cook, you make your mashed potatoes slightly runnier and you don't require the item to be covered so the moisture can be better evaporated. This is culinary science at its finest - a chef that can deconstruct a meal and package it into a reheatable meal served on one tray wears a hat just like someone at the french laundry - and with good reason.

Sure, the food quality might not the same - and the quality of the product might be slightly above grade 'C' but the reality is it took a ridiculous amount of respect for the food to create your hungry man dinner.

Want to know the next upcoming food trend? Gourmet TV dinners. When the first restaurants open, It'll make Momofuku look like really expensive breakfast cereal.
posted by Nanukthedog at 3:23 PM on April 15 [3 favorites]

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