In the page linked to below, is a chart that shows the poor to excellent brix readings (numbers) for fruits and vegetables. It's a good intro.
I was getting very poor readings even from organic CSA food, claimed to be grown in rich soil (the farm being previously only a horse farm). Disappointing!
Then I had some really good peaches and nectarines. Totally forgot to test them, since I've been at this awhile now. And now blue grapes- So good they make you want to mono-feast.
If you don't know what "brix" is, you might want to find out, and maybe buy yourself a refractometer. It's quite the discovery/adventure. I got mine on ebay: a 0-32 scale for about 40 dollars.
I just tested this year's first crop of concord grapes; basically, you can probably already tell if the brix is high by the taste. (People don't like low-brix fruit or veg. so that might solve a few mysteries, if you or someone isn't drawn to something.. You know how kids will eat a whole tomato straight off the vine if it's good, but maybe won't touch that store-bought one?)
The thing is, if a food is high-brix you really do want to eat it, the body knows what's good for it. Low-brix food is acid, and acid-forming. Eat high-brix and you need less, (more nutrients), and, you don't get so many cravings for other, "bad" (processed) food.
I knew the brix was high on the concords, but it's so nice to see measurable confirmation. . "off the charts".
There's another way to tell if fruit and veg. are good quality. They don't attract pests. Pests, when they get out of balance, are nature's garbage collectors. Their job is too get rid of what's not good, or control it. It's a myth you sometimes see promoted, that organic food doesn't 'look good.'
If it doesn't, it's usually because it ISN'T good. There are exceptions of course, in that there is a lot of 'big food' out there now, that is shiny and clean looking, and keeps forever --like a lot of the tomatoes... but dead, and frankenfood. (Check this, with the refractometer, and you will soon be able to save yourself buying poor food,) "As above, so below" applies also to 'as within, so without.' Lots of pests within = low nutrition, lots of pests without: on the food grown, means that it's low quality. When you consider that, it puts the world of pesticides into interesting focus.
We wouldn't need them if the food was good. . . .