Even if you weren't worried about the environmental (or other) impact of throwing out food, there is clearly a non-zero cost associated with acquiring a second gallon which you will not drink. You have to carry more stuff home, keep more stuff in your refrigerator, worry about and monitor the state of the milk in the refrigerator, and throw away the milk once it's bad. It is very clearly a worse deal in every way.

Which might work with milk (maybe not), but not with the nuggets you buy at Maccas.

I make yogurt with the second gallon. It feels like magic: I get cheaper milk and cheaper yogurt (free modulo a very modest investment of effort).

Agreed. Pour a gallon of milk in a crock pot, heat it to the Right Temp (I forget what that is), add a teaspoon of regular yogurt (for culture), and then let it sit (I forget at what temperature). It's tremendously simple.

You basically want it a little above body temperature. My crock pot is too hot, even on its lowest setting, so I just use it as a dumb insulated water bath. I heat it to about 45 C, turn it off and let jars of milk/culture sit in the bath overnight.

I also boil the milk and then let it cool to 45 C. This achieves a few things: it kills off any other bacteria that may be in the milk and it denatures the milk protein so that it sets thicker. Costco milk is probably pasteurized at a high enough temperature that this isn't necessary, but I've always done it this way.

Yogurt is really forgiving. I've daydreamed a bit about making a temperature regulator for my crock with an Arduino or similar, but it's honestly not necessary. People get good results simply wrapping a jar with towels.

You can freeze milk, you know!

My chest freezer has probably been the most economical purchase I have made in the past few years. It sips electricity and keeps (almost) everything as fresh as the day I purchased it.

Frozen milk becomes milk fat and off white water. No thanks

Have you actually experienced this personally? Because I freeze milk routinely, and have never had any problems.

Let it thaw completely of course.

>Let it thaw completely of course.

That seems to be the key with any frozen material.

We were worried that our cheese wasn't freezing properly for the first few weeks, until I realized that a 1-2 day de-thaw inside of a refridgerator was necessarry to bring it back to it's true self.

Cream cheese however never returns to its normal self after freezing. It even says so on the package "do not freeze". The flavor is fine, but it becomes crumbly instead of creamy.

Cottage cheese also freezes badly. Hard cheese does fine though.

Try blending it once de-thawed if you're experiencing that.

Skimmed and semi-skimmed milk tends to freeze better than full fat milk.

> Throwing out food feels bad.

I always thought it was a strategy to train your progeny for the next famine / war.

Instead of the abstract advice "By the way, if your grandchildren are even in a middle of a famine, they should remember to eat all the food they can find."

You give a concrete actionable threat "Eat the last nugget, but now!" and wish it get passed down until it's useful.

I've been doing this for 35 years. I don't recommend it :)

> Throwing out food feels bad.

There's a positive side effect where your purchase impacts Costco's sales volume, which impacts their negotiating position with the suppliers, which makes the same product cheaper for everyone else.

You mean, it's better to throw away milk, so you can screw farmers by proxy?

The farmers get to sell more milk.

have to sell more milk.

For an established cow farmer adding additional cows at marginal cost to receive additional revenue is economies of scale. Forcing them to allocate resources to the areas where they don't enjoy economies of scale is likely to raise their cost and not lead to optimal outcome.

I'm not sure this is exactly loss aversion, but perhaps it's related. I would happily give the second gallon of milk to anyone who wanted it for free. That loss would make me feel better, even though I've still lost the second gallon.

Interesting, this is very observable in the mating selection area.