How to Keep Food For a Long Time in the Refrigerator Without Spoiling

It's easy to keep food from going bad before its time in the fridge, and to make its time longer than ever before, when you understand two words: Danger Zone.  Once you understand how to work around the Danger Zone, your food will last far longer.
I have a few secrets that I use to keep food safe for a long time. After I explain why these secrets are important, I give some key rules at the bottom of this post.

What is the Danger Zone?

The Danger Zone is the range of food temperature at which bacteria grows and thrives. It is worst from Celsius 10 - 55 (Fahrenheit 55 - 134), and still at risk from Celsius 3 - 60 (Fahrenheit 40-140). It's dangerous to handle or leave food in this temperature zone. This is the zone you need to learn to work around creatively.

C Max Temp	F Max Temp	Description
-	-	Assured Pasteurization Zone
64	147	Start of Pasteurization Zone
60	140	Tolerance Zone
55	134	Danger Zone
50	122	Extreme Danger Zone
20	68	Danger Zone
10	55	Tolerance Zone
3	40	Secure Zone

Can I Avoid the Danger Zone?

No. You can't avoid the danger zone. All food spends time in the danger zone.

So I Have To Rush Food Through The Danger Zone?

No. Well, rushing doesn't hurt. But rushing food through the danger zone is neither necessary nor sufficient.
First, take the case of all the canned food that has been sitting safely on your shelves for months. It is in the Danger Zone, but there's no rush.
Second, take the case that you have a steaming hot pot of stew you are rushing to cool from the Pasteurization Zone to the Secure Zone. You walk out of the room, and while you are out and the stew is in the top of the Danger Zone (in the refrigerator), I get a dirty spoon, sneeze or cough into the pot, stir the pot, and serve myself a delicious bowl of stew. I just sabotaged your food safety by seeding your entire pot with well-distributed cultures of bad bacteria, and your stew still has to cool down through the danger zone!
Of course the case is worse if you serve the stew hot to the family and we spend the evening stirring and serving ourselves until the stew is cool (Danger Zone), then you put it in the refrigerator. Your rush in the second case scenario gives you some advantage, but not enough. There's more to the equation than rushing through the danger zone, or temperature and time. There's bacteria.

What About Bacteria?

Of course your goal is simple. You just want to get your food down to the secure zone with as few live bacteria as possible so it will be safe as long as possible. So you need to kill all the bacteria in the food, then avoid contaminating it with more bacteria until it is in the secure zone (near freezing).

Enough Chat, Can I Just Have The Rules?

I'd rather explain the principles than give rules, but here are some simple rules for making your food last long in the fridge.

1. Start with sterile food. Heat to the Assured Pasteurization Zone (2.5 second skin burn time) for 1/2 hour, or to boiling momentarily.
2. Transfer food carefully to cooling containers while it is at maximum temperature. Seal immediately.
3. Keep food sealed while it cools.
4. Be cautious of risk to other food when hot food is placed the refrigerator. Balance your need to rush with the need to keep the refrigerator near freezing. Rely on your anti-bacterial seal to keep food sterile while it cools.
5. Cool to near freezing before unsealing.
6. Return unused portion to fridge immediately after serving, or return to step 1.
7. Cool all canned food (salsa, peanut butter, etc) to near freezing before opening it, or go to step 1 after opening.
8. When you make fruit juice from concentrate, try to start with a sterile pitcher and tight-fitting lid every time unless (unlikely) you want to go to step 1. Pre-thaw the concentrate in the refrigerator, use ice-cold mixing water, and swirl, shake, or use a hot, sterile utensil to mix. Keep the pitcher in the coldest part of the the refrigerator at all times. The walls of the pitcher can quickly heat up outside the fridge and start growing bacteria that is later washed into the juice.
9. To mix up juice or other cold items (sauces and drinks) before serving, shake, swirl, or use a hot, sterile spoon.
10. If practical, pour or squeeze liquids and sauces directly from the container instead of dipping them.
11. Study your refrigerator's zones. Learn where the freezing air comes from the freezer (usually at one or two places on the wall between the refrigerator and the freezer). Place the food with the longest desired life (massive leftovers) and the highest vulnerability (fruit juices) in the coldest spots. Avoid the door shelves for any vulnerable food.