Archive for starch/iodine test
Its getting quiet in the orchard, only a few trees left with fruit still hanging. The colors have been beautiful and still no hard freeze here at our place. We can see snow up on the higher ridges and peaks above us, it won’t be long until its here in the lowlands.
A few new varieties this week:
–Northern Spy Apple
–Newtown Pippin Apple
-A-Ri-Rang Asian Pear
Also this week:
-Prairie Spy Apple
-King David Apple
-Belle de Boskopp Apple
-Hosui Asian Pear
-Walnuts (the last of them)
This Saturday at the University District Farmers Market in Seattle, along with the regular market activities AppleLooza will be taking place. A celebration of Apples, there will be a apple tasting, apple info and an pie making demo. I will also be there demonstrating a low tech method to check apples for ripeness. (See my September 15 post about the subject) Come enjoy and celebrate great Washington state apples!
See you Saturday.
I’m often asked when the right time to pick an apple is, a fruit may look ripe for weeks before its optimally ready to harvest. It varies from variety to variety, different years may change the pick day, and what the fruit is intended for has some bearing on when to harvest (i.e. for immediate consumption or long term storage). I use a few tools; a pressure tester (or Penetrometer) , a refractometer and a solution of iodine. The first two are quite useful but not necessary for checking backyard fruit.
The pressure tester is used to check the density of the fruit ( Also the main way to check Pears for ripeness) the probe end is inserted into the fruit (a flat spot cut) to the indented line on the probe end and the dial indicates how much pressure to get to that point .
Then I check the soluble solids, brix level or basically the sugar of the fruit with the refractometer. I keep track of all the info leading up to optimum harvest from year to year, so I know about when a particular variety will be ripening. Like I said before, this is all neat o tools which if you can afford, like this kind of thing and have fruit to test, get it. But my favorite and really telling way of checking apple maturity is the starch /iodine test. And very economical too.
The above (and below) photo was taken September 14th, the apples are cut cross across the core, exposing the seed cavity. A iodine solution was sprayed on (below photo) and what is revealed is the sugar to starch ratio of the fruit. The iodine stains the starch in the fruit black but not the sugar.
Starting at the upper left, going across then back to the lower row. I started with the Sunrise apple which I knew to be too ripe (was left on the tree after I harvested them a couple of weeks ago) shows all sugar. At that point its too ripe and soft, good for apple sauce. The next three show a good mix of starch to sugar, the Arlet apple is optimum (I’ve already started picking them) the Pink Pearl and McIntosh will come off soon. The lower row shows mostly a starch pattern except the Coxs Orange Pippin in which I’ll do some further testing, but is at the point in the photo which would be good for long term storage. The others on the bottom row I’ll keep track of and test in coming weeks, all still too green . A apple too ripe, as the Sunrise is bland and soft, the next few have a good blend of starches and sugar but won’t keep for long (a few weeks in a fridge). For long term storage the fruit needs to be somewhat along in ripening but not too far, the vascular bundle (the area around the seed cavity) needs to be sugar. Thats part of the trick to getting the fruit ripe enough but not too ripe, if picked to green or starch it won’t ripen no matter how long its stored. Another indicator of when to start testing is the seeds, they need to be turning or be brown. And generally early apples won’t keep as long as later apples will. If you only have a few apples and aren’t concerned with storage, taste it!