every resource mentions having "blemish free" produce.

What resources? Examples please.

NCHFP specifically talks about "trimming off any bruised or damaged portions" on most of its recipes. So do many of the Ball recipes. But that is just a common sense practice anyway.

Quality: Select only disease-free, preferably vine-ripened, firm fruit for canning.

Caution: Do not can tomatoes from dead or frost-killed vines. Green tomatoes are more acidic than ripened fruit and can be canned safely with any of the following recommendations.

The only "prohibited" is tomatoes that have been killed by frost (or late-blight infected tomatoes). Other severely diseased or damaged foods are recommended against of course but again, it is common sense for the most part.

Damaged produce is poor quality produce, depending on the amount of damage. Both flavor and texture can be affected.
So why spend on the effort and expense of preserving poor quality foods. The old saying "junk in equals junk out" applies.

Damaged produce is also much more likely to be infected with bacteria, molds, etc. so each person has to decide how much damage is too much when it comes to canning.

There is a big difference between healthy green beans with a few bad spots that can easily be cut out and green beans infected witht bean rust. Between a bruised tomato or one with some spots on the peel that gets removed anyway vs. tomatoes with fruitworms holes or grey mold growing out of the skin splits.

Common sense prevails in canning just as in all things.

Dave

Well Dave, pretty much all sources explain just as you have. So, a person reading that, but has a product that does in fact have a bruise or a black spot, it makes them question if it should be used or not. It always says not to, but not why. I cut spots out of tomatoes, appples, pears, potatoes, etc, all the time for cooking, and have for canning, but I was just curious if it was truly recommended to not use fruit that has bad spots period. That perhaps produce with one bad spot, even though spot is removed, can mean a spoilage factor for the overall final product.

Since you informed me, Dave, of the possiblity of corn being deemed "inedible" I was really being precautious.

When it comes to canning, nothing can be based on common sense. It appears everything must be scrutinized and I respect the reasons why.

It boils down to would you eat it fresh? If not then you sure wouldn't want to can it.

I don't recall the issue with the corn but there must have been some specific issue. I wouldn't have said that all corn was inedible for any reason. Certain diseased corn? Sure, avoid it just like any diseased foods.

I'm all for not wasting foods but you have to draw the line somewhere and when the poor quality and/or presence of bacterial disease far outweighs any benefits to be gained that's where I draw the line.

Dave

Dave, a couple weeks ago I was questioning how others here deal with a lot of produce being ready all at once. In the discussion I had mentioned all the produce I had on that particular day, and where it all came from. When the subject of corn came up, I had mentioned that a lot of sweet corn here didn't grow well due to drought and heat. Many people just threw away their corn that only half the ear was edible, the other half was undeveloped kernels or seriously worm eaten. I was not allowing any corn to go to waste so I took the time to cut away all the bad spots and proceed with corn cut off the cob after blanching. People finding out here that I was salvaging imperfect corn started bring theirs to me. I mentioned this in conversation and you had told me to check with my Extension office about mold and bacterial issues that in some areas (yours?) had deemed it in edible.

Ellen, here the corn mostly all had corn ear worms at the tip. I cut off the tip and canned the rest.

The one thing that'll cause me to throw out the entire fruit is BER. Blossom End Rot on tomatoes gives the tomato a flavor that seems to permeate the entire fruit for me. Other people say they don't notice, but I do, so I won't can those. I don't eat them either.

I cut bad spots out of apples that go into my cider press too, which is more than the commercial guys do. Their apples are picked up, sometimes from the ground. No bad spots or bugs are removed, it all goes into the press where they press 'em. They do pasteurize it, though!

Annie

I mentioned this in conversation and you had told me to check with my Extension office about mold and bacterial issues that in some areas (yours?) had deemed it in edible.

Ahh corn smut and Gibberella ear rot was what I was talking about. Yes given the weather issues and corn crop failures in much of the country this year both contaminants have been widespread. Both are serious fungal diseases as is Diplodia, another disease that result in half formed, semi-desiccated ears. Thus the suggestion to check to see if they were prevalent in your area this year. Especially if you don't know the symptoms to check for.

And yes, you definitely wouldn't want to can corn with either of those issues.

Dave

Thanks Annie. Blossom end rotted tomatoes I do not mess with. Typically, here, it occurs primarily with the early on tomatoes, the first few before the big flush of fruits come on. I just throw them out. This late in the season I'm mostly seeing black cracks on the tops of the tomatoes, but I pick them at earliest sign of blush color, and that keeps it from happening much better. In the middle of summer, I can let the tomatoes stay on the vine much longer than I do now.

How sickening about the commercial cider. I'm picking apples this evening, how will I get that vision out of my head?! I think the more I hear of such stories, the more and more I want to grow and preserve my own. Currently, the kind folks here on Gardenweb have advised me to slow down. And that I did.

Thanks Dave. We did have mold here but not all corn was unsalvageable. I seem some sold in the grocery stores that looked just like mine did. I have to say I've never seen fresh corn that looked so terrible. But if it's edible, die hards like me will salvage it. Corn this year does not have the great flavor it normally does. You are correct, I would not have known of conditions other than mold. But I certainly would have researched whatever seemed suspiciously abnormal. Next year just has to get better!! My local news reported that 2012 was the fourth hottest summer on record. 2011 was the fifth hottest. And 2010 was the sixth. I was surprised by the 2010 record. What is in store for 2013???

I'm a biochemist, I can tell you why all the books say "blemish free". The canning process kills the vast majority of bacteria, but the processing times were developed for relatively clean, fresh produce. Partially rotten fruit or vegetables have more bacteria to begin with, so 20 minutes in a boiling water bath might not kill them all. Writers of canning books don't want anyone to get sick.

And, of course, the bad fruit doesn't taste as good.

I do just cut out bad pieces and can it anyway. I even make applesauce out of the spotty apples that fell on the ground!

I even make applesauce out of the spotty apples that fell on the ground!

Then I hope you are adding acid to that. Windfall apples aren't as acidic as harvested apples and contain even more bacteria. So adding additional acid is required per the guidelines.

Dave

Dave, what is the timeframe for a fallen apple to become diseased/damaged as you just explained? We just had a wicked windstorm here, was planning to pick apples off trees tonight but got rained out. I plan to pick in the morning. I have no doubt that many apples fell this evening. What timeframe does an apple have from tree to fallen to pick up? I dont use fallen apples but surely many good apples fell. Would it be too late by mid morning to salvage them?

There is no given time frame. Too many variables so the guidelines treat all fallen apples the same. If it is picked off the ground rather than from the tree it is a windfall.

But many bacteria grow quickly. Most bacteria will have a high level of growth within 24 hours given the right conditions.

Windfall apples can be used, they just require added acid.

Dave

I see. Thanks Dave. I assume this applies to pears as well? This is all good to know, as apples and pears both will show up on my doorstep from unknown sources.

Not at all. I often buy seconds for canning, since they are considerably cheaper. But I cut away any bruised areas. I wouldn't use moldy produce, but aside from that, "perfect" isn't necessary.