Reheating no boil lentil lasagna noodles after freezing

There are a variety of factors at work here:

1. Freezing foods "improperly" (i.e. not flash-frozen, not vacuum-sealed) causes ice crystals to form within the food, damaging the molecular structures. This is what causes many frozen leftovers to become "mushy" or change in texture.

2. Again due to the formation of ice and the movement of water when the food is reheated, tiny particles such as spices can be lost in steam and/or runoff water.

3. Extreme temperatures (both hot and cold) can denature enzymes in the food, changing their flavor, texture, etc.

4. As food sits, flavors in the food may blend together in different ways, causing the food to have less distinct flavors.

5. If your freezer isn't especially clean and your food not well-sealed, your food may be absorbing other odors which are again "masking" the original flavor of your food.

Hope that gives you some ideas.

It has nothing to do with the microwave and everything to do with the volatility of aromas and flavors in coffee. Even coffee kept warm for 4 hours won't taste very good. In my experience, stale brewed coffee results in a more pronounced acidity, if left out to cool, or a woody, muddy, bitter kind of flavor, sometimes with more pronounced acidity, if held warm. If you were to make a straight espresso, it's optimal to drink it within 20-30 seconds. Brewed coffee can usually be held warm around 30 minutes before pronounced deterioration becomes obvious.

A popular Japanese TV show suggested perhaps stirring a pinch of salt in to stale, reheated coffee, which may trick your tastebuds enough into tolerating it. I've found that tactic less than adequate, but your mileage may vary.

There's a ton of information on coffee flavor compounds and other coffee-related research at: http://www.coffeeresearch.org/science/aromamain.htm